JP4335036B2 - Ranging device and ranging method - Google Patents

Description

  The present invention relates to a distance measuring apparatus and a distance measuring method for measuring a distance to an object to be photographed when a subject is photographed by a camera or the like, and more particularly to a distance measuring apparatus and a distance measuring method capable of performing passive distance measurement.

Conventionally, a distance measuring device capable of performing passive distance measurement mounted on a silver salt camera, a digital camera or the like includes a lens for a photographing camera and a line sensor including a plurality of light receiving elements apart from a CCD. It is possible to measure the distance to the object to be imaged by judging how much the difference data indicating the difference in brightness between adjacent pixels is shifted from the data of a plurality of elements input to the line sensor. it can. A technique for measuring this distance with high accuracy is described in Patent Document 1. According to Patent Document 1, when the data input to the distance measuring device has low luminance and low contrast, the reference voltage used for the integration control is switched to a high voltage and the integration for the input data is performed again. It describes that a photoelectric conversion operation is performed.
JP 2003-29133 A

  However, in the technique according to Patent Document 1, when the contrast data input to the distance measuring device is determined to have low luminance and low contrast as shown in FIG. 12B, the integral photoelectric conversion operation is performed again. Therefore, there arises a problem that the distance measurement time is considerably longer than the normal case shown in FIG.

  Further, when the contrast data has low luminance and high contrast, a process of raising the low luminance portion is performed as shown in FIG. 13A, but the overall processing is performed as shown in FIG. 13B. However, when the brightness is high and the contrast is low, the integral photoelectric conversion operation is not performed again, but there is a problem that high-precision distance measurement cannot be performed.

  Therefore, an object of the present invention is to realize a distance measuring device and a distance measuring method that can perform highly accurate distance measurement without performing reintegration photoelectric conversion operation.

To solve the above problem, the distance measuring apparatus of the present invention comprises a pair of light-receiving sensor for distance measurement comprising a plurality of light receiving elements for receiving light reflected from the object to be shot, received by each of the pair of light receiving sensors a / D converting means for converting the luminance data of the reflected light to a pair of digital data, using a pair of digital data converted by said a / D converting means, adjacent to every other of the plurality of light receiving elements by calculating the difference between the luminance data among the light receiving elements, and the difference data conversion means for converting the digital data into a pair of differential data for correlation calculation of a predetermined bit, a pair of differential data converted by the difference data conversion means the high contrast data to be converted to a pair of high-contrast data height difference of contrast is expanded in the luminance data of the reflected light received by the plurality of light receiving elements Conversion means, and a calculating means for calculating a distance to the high contrast data conversion means pair of the imaging object using high contrast data converted by said high contrast data conversion means, with a predetermined N-bit table The difference data having the maximum value is extracted from the difference data, and the highest order bit is extracted from the extracted difference data N bits, and the highest bit with 1 other than the highest order is attached to the top ( M-1) By extracting bits (M <N), the contrast level is converted into high contrast data in which the difference in height is enlarged, and the calculation means is a pair obtained by conversion by the high contrast data conversion means. High-contrast data, which is classified for each distance measurement area unit to be correlated, For each distance area unit, the pair of high contrast data ranging areas is calculated using a pair of windows, and the degree of correlation of a part of the pair of high contrast data is calculated, and the pair of windows are located within the distance measuring area. Each time a quantitative shift is performed, the correlation degree is calculated, and the distance to the object to be photographed is calculated based on the distance measurement area having a high degree of correlation obtained according to the result of the calculation process and the shift amount of the window. It has that.

Further, the distance measuring method of the present invention includes an input step of inputting luminance data of reflected light from an object to be photographed through a pair of light receiving sensors for distance measurement composed of a plurality of light receiving elements, and a pair of input luminance data. Calculating a difference in luminance data between light receiving elements adjacent to each other in the plurality of light receiving elements, using a first conversion step of converting the digital data into a pair of digital data, A second conversion step for converting digital data into a pair of differential data for correlation calculation of a predetermined bit, and a contrast level in the luminance data of reflected light received by a plurality of light receiving elements is converted into a pair of converted differential data. A third conversion step for converting into a pair of high-contrast data with an enlarged difference and a distance to the object are calculated using the converted pair of high-contrast data. A third conversion step, wherein the difference data having the maximum value is extracted from the difference data represented by predetermined N bits, and the highest bit is extracted from the extracted difference data N bits. Is extracted and (M-1) bits (M <N) are extracted starting with the highest bit with 1 other than the highest one, and converted to high contrast data in which the difference in contrast is expanded. The calculation step includes a pair of high contrast data obtained by the conversion in the third conversion step, and the high contrast data divided for each ranging area unit to be subjected to correlation calculation For each ranging area unit, the pair of high contrast data ranging areas are used as a pair of windows, and the degree of correlation of a part of the pair of high contrast data Each time the pair of windows is shifted by a predetermined amount within the distance measurement area, the correlation degree calculation process is performed, and the distance measurement area having a high correlation degree obtained according to the result of the calculation process and the window It is characterized by calculating the distance to the object to be photographed based on the shift amount.

In the above-described configuration of the present invention, the luminance data of the reflected light from the object to be photographed is input through a light receiving sensor composed of a plurality of light receiving elements, the input luminance data is converted into digital data, and the converted digital data is correlated. The difference data is converted to high-contrast data in which the difference in contrast is expanded among the data received by a plurality of light receiving elements. It is possible to calculate appropriate data when measuring distance without performing re-calculation processing of data conversion when the luminance data is low luminance, and it is possible to reduce the distance measuring time and the photographing time. be able to.
In addition, from a plurality of difference data formed by N bits, one difference data having a maximum value is extracted, and when this difference data is expressed by M (M <N) bits, the maximum value can be taken from N bits. By extracting M bits, high-contrast data can be obtained, and high-contrast data can be obtained with a simple configuration.

  The distance measuring apparatus according to the present invention further includes a judging means for judging the degree of contrast with respect to the difference data represented by a predetermined number of bits N, and the high contrast data converting means has the contrast determined by the judging means. Depending on the degree, conversion may be performed by changing the degree of increasing the contrast difference.

  In the above-described configuration of the present invention, it is possible to convert to appropriate high contrast data by changing the degree of conversion according to the degree of contrast.

Further, the distance measuring device of the present invention includes a pair of light receiving sensors for distance measurement composed of a plurality of light receiving elements that receive reflected light from an object to be photographed, and the luminance of reflected light received by each of the pair of light receiving sensors. A / D conversion means for converting data into a pair of digital data, and a pair of digital data converted by the A / D conversion means, the luminance between adjacent light receiving elements in the plurality of light receiving elements By calculating the difference between the data, the digital data is converted into a pair of differential data for correlation calculation of a predetermined bit, and the pair of differential data converted by the differential data conversion unit is converted into the plurality of differential data. High-contrast data conversion means for converting into a pair of high-contrast data in which the difference in height of contrast is enlarged in the luminance data of the reflected light received by the light-receiving element; And a calculating means for calculating the distance to the photographed object using a pair of high-contrast data converted by the contrast data conversion unit, the high contrast data conversion means among the difference data representing at predetermined N-bit , The difference data that is smaller than the center value that is the center of the maximum value and the minimum value represented by N bits and that is closest to the center value is extracted, and the highest order bit is extracted from the extracted difference data N bits By extracting (M−1) bits (M <N) starting from the bit with 0 other than the highest-order bit, it is converted into high-contrast data in which the difference in contrast is expanded, and the calculating means A pair of high-contrast data obtained by conversion by the high-contrast data conversion means, for each ranging area unit to be subjected to correlation calculation For the divided high-contrast data, for each distance measuring area unit, the pair of high-contrast data ranging areas is calculated using a pair of windows to calculate the degree of correlation of a part of the pair of high-contrast data. Each time the pair of windows are shifted by a predetermined amount within the distance measurement area, the correlation degree calculation process is performed, and the distance measurement area having a high degree of correlation obtained according to the result of the calculation process and the shift amount of the window are calculated. And calculating a distance to the object to be photographed.
Further, the distance measuring method of the present invention includes an input step of inputting luminance data of reflected light from an object to be photographed through a pair of light receiving sensors for distance measurement composed of a plurality of light receiving elements, and a pair of input luminance data. Calculating a difference in luminance data between light receiving elements adjacent to each other in the plurality of light receiving elements, using a first conversion step of converting the digital data into a pair of the converted digital data, A second conversion step for converting digital data into a pair of differential data for correlation calculation of a predetermined bit, and a contrast level in the luminance data of reflected light received by a plurality of light receiving elements is converted into a pair of converted differential data. A third conversion step for converting into a pair of high-contrast data with an enlarged difference and a distance to the object are calculated using the converted pair of high-contrast data. A high-contrast data conversion step, wherein the high-contrast data conversion step is smaller than the central value that is the center between the maximum value and the minimum value represented by N bits in the difference data represented by predetermined N bits. The difference data closest to is extracted, and the highest-order bit is extracted from the extracted difference data N bits, and the bit with 0 other than the highest-order bit is (M−1) bits (M <N ) Is converted into high-contrast data in which the difference in contrast is expanded, and the calculation step is a pair of high-contrast data obtained by conversion in the third conversion step, For high-contrast data divided for each ranging area unit to be calculated, the pair of high-contrast data for each ranging area unit Using the pair of windows in the distance measurement area, the degree of correlation of a part of the pair of high contrast data is calculated, and the degree of correlation is calculated each time the pair of windows are shifted by a predetermined amount within the distance measurement area. And calculating the distance to the object to be photographed based on the distance measurement area having a high degree of correlation obtained according to the result of the arithmetic processing and the shift amount of the window.

In the above-described configuration of the present invention, differential data having a value lower than the central value and closest to the central value is extracted, and the difference between the central value here and the differential data formed by M bits is maximized. By extracting M bits from N bits, high contrast data can be obtained, and high contrast data can be obtained with a simple configuration.

  The present invention includes high-contrast data conversion means, and calculates appropriate data when measuring the distance without performing re-calculation processing of data conversion when the data received by the light receiving sensor has low brightness. As a result, the distance measurement time can be shortened and the photographing time can be shortened.

  Hereinafter, embodiments of a distance measuring device according to the present invention will be described with reference to the drawings.

  FIG. 1 is an external view of a camera device provided with a distance measuring device of the present invention. FIG. 1 (a) is a front perspective view, and FIG. 1 (b) is a rear perspective view.

  In FIG. 1A, an autofocus sensor window 10 is a sensor window used for measuring a distance to an object to be photographed by a passive distance measuring method, and will be described later via the autofocus sensor window 10. Image data serving as sensor data is input to the distance measuring lenses 1A-L and 1A-R. The lens 11 is used to input photographed object data to the CCD. The shutter button 12 is a button for an operator to operate when shooting an object to be shot. The strobe 13 irradiates light to the photographing object in order to secure a light amount when photographing the photographing object. The stroboscopic light control sensor 14 is a sensor that determines whether or not the amount of light applied to the object to be photographed with the stroboscope 13 is appropriate and adjusts the amount of light. The finder window 15 is a window that allows an object to be visually recognized by an operator looking through a finder 16 described later.

  In FIG. 1B, the finder 16 enables an object to be visually recognized by an operator looking through the finder 16. The operation unit 17 is a switch capable of setting an operation mode such as strobe pop-up, operation cancellation, function selection, moving image / still image / reproduction. The liquid crystal display unit 18 displays the result of the operation performed by the operation unit 17 and displays the reproduced moving image and still image. The power button 19 is a switch for turning on / off the power of the camera device.

  A distance measuring device mounted on such a camera device will be described. FIG. 2 is a block diagram of a distance measuring device mounted on the camera device.

  A distance measuring apparatus according to an embodiment is a distance measuring apparatus used to calculate a distance from a photographing lens to a photographing object in, for example, an AF (Auto Focus) camera or a video camera. As shown in FIG. 2, the distance measuring device includes a pair of left and right distance measuring lenses 1A-L and 1A-R, and distance measuring lenses 1A-L and 1A-R. A pair of left and right line sensors 1B-L and 1B-R (light receiving sensors of the present invention) as light receiving sensors on which images of the object S are formed, and signals from the line sensors 1B-L and 1B-R are processed. A line sensor unit 1 having a line sensor control circuit 1C for performing the distance measurement, and a distance measurement calculation for calculating a distance to the object S based on sensor data output from the line sensor control circuit 1C of the line sensor unit 1 The apparatus 2 is provided.

  The line sensors 1B-L and 1B-R are configured by arranging cells (pixels) such as photodiodes divided into a large number, such as 234, for example, in a straight line. Each cell of the line sensors 1B-L and 1B-R photoelectrically converts the amount of light of the image of the photographing object S formed on the respective light receiving surfaces, thereby converting the luminance signal of the image of the photographing object S to the line sensor. Output to the control circuit 1C.

  Each cell of the line sensors 1B-L and 1B-R is assigned a cell number used when the output signal is taken out. For example, the cells of the left line sensor 1B-L are assigned cell numbers L1 to L234 in order from the left side of the figure, and the right line sensor 1B-R is assigned cell numbers of R1 to R234 in order from the left side of the figure. Is done. Since the five cells on the head side and the five on the tail side of the left and right line sensors 1B-L and 1B-R are so-called dummy cells, the number of effective pixels of the left line sensor 1B-L is L6. 224 of L229, and the number of effective pixels of the right line sensor 1B-R is 224 of R6 to R229.

  The line sensor control circuit 1C controls the line sensors 1B-L and 1B-R in accordance with a command signal from the line sensor control unit 2A of the distance measuring operation device 2 described later, and the line sensors 1B-L and 1B-R. A luminance signal is input from each cell in association with the cell number. The line sensor control circuit 1C integrates (adds) the input luminance signal to generate sensor data to be used for correlation calculation in association with the cell number for each cell. Incidentally, this sensor data indicates a lower value as the image of the subject S is brighter and a higher value as the image is darker.

  The ranging calculation device 2 is configured using microcomputer hardware and software. The distance measurement calculation device 2 includes an A / D conversion unit 2B that converts analog sensor data input from the line sensor control circuit 1C via an input / output interface into a digital signal, as well as the A / D conversion unit 2B. RAM (Random Access Memory) that temporarily stores sensor data of the digital signal converted by the above, ROM (Read Only Memory) that stores programs and data for calculating the distance to the object S, and the ROM Hardware (not shown) such as a CPU (Central Processing Unit) that performs various arithmetic processes for calculating the distance to the object S based on data stored in the ROM and RAM by executing the stored program Wear.

  In this distance measuring calculation device 2, in order to calculate the distance to the object S based on the sensor data generated by the line sensor control circuit 1C, the line sensor control unit 2A, the A / D conversion unit 2B (of the present invention). Sensor data conversion unit 2C (difference data conversion unit, high contrast data conversion unit and determination unit of the present invention), sensor data storage unit 2D, correlation calculation unit 2E, window shift unit 2F, local minimum A value determination unit 2G, a distance measurement error determination unit 2H, a distance calculation unit 2I (calculation means of the present invention), and the like are configured as software.

  The sensor data conversion unit 2C converts the 12-bit data converted by the A / D conversion unit 2B into difference data. As shown in FIG. 3, the difference data is obtained by taking a difference indicating a difference in luminance between adjacent pixel data in the pixels of the line sensor. Further, the converted 12-bit difference data is converted into 8-bit data. When converting to 8-bit data, determine which bits to extract so that the degree of enlargement can be changed according to the degree of contrast, and extract bits according to the method described later so that high-contrast data can be obtained. To do.

  The sensor data storage unit 2D stores, as sensor data, differential data that is converted by the sensor data conversion unit 2C and represents the obtained 1 data in 8 bits.

  The window shift unit 2F controls a shift operation of a pair of windows WL and WR (see FIG. 4) for reading a pair of sensor data used for correlation calculation from the sensor data stored in the sensor data storage unit 2D.

  As shown in FIG. 4, the window shift unit 2F includes a central area M, a left area L, and a right area R, which are sensor areas partially overlapped on the line sensors 1B-L and 1B-R. The shift operation of the pair of windows WL and WR is controlled so that a group of sensor data is read from the sensor data storage unit 2D for each distance measurement area unit and subjected to correlation calculation. In this case, the window shift unit 2F controls the shift operation of the pair of windows WL and WR in the order of the center area M, the left area L, and the right area R, for example.

  Here, in the shift operation in each central area M of the line sensors 1B-L and 1B-R shown in FIG. 4, the window shift unit 2F sets the window WL corresponding to the left line sensor 1B-L to the right end of the central area M. The window WR corresponding to the right line sensor 1B-R is sequentially shifted one by one from the position corresponding to the initial position to the position corresponding to the maximum shift position at the left end, and the position corresponding to the initial position at the left end of the central area M. Are sequentially shifted one by one to the position corresponding to the maximum shift position at the right end. At that time, the window shift unit 2F shifts the windows WL and WR alternately one by one.

  Note that the shift operation in each left area L and each right area R of the line sensors 1B-L, 1B-R by the window shift unit 2F is substantially the same as the shift operation in each central area M, and thus detailed description is omitted. To do.

  Returning to FIG. 2, the correlation calculation unit 2 </ b> E is configured so that a pair of windows WL and WR are alternately placed one by one in each of the ranging areas M, L, and R set on the line sensors 1 </ b> B-L and 1 </ b> B-R, respectively. Each time a shift operation is performed (see FIG. 4), a group of sensor data is read from the sensor data storage unit 2D and a correlation calculation is executed.

  This correlation calculation calculates the absolute value of the difference between each sensor data between the group of sensor data read by one window WL and the group of sensor data read by the other window WR. The sum of absolute values is obtained as a correlation value. This correlation value indicates that the smaller the value is, the higher the degree of correlation is, and the images of the imaging target S imaged on the pair of line sensors 1B-L and 1B-R are similar to each other.

  Here, when the photographing object S is located at a long distance, the photographing object formed on the pair of line sensors 1B-L and 1B-R through the pair of distance measuring lenses 1A-L and 1A-R. A pair of images of the object S to be imaged on the pair of line sensors 1B-L and 1B-R as the positional deviation between the pair of images of the object S becomes smaller and the object S is located at a shorter distance. The positional deviation of becomes larger. Then, the magnitude of the positional deviation between the pair of images is obtained by the shift amount of the pair of windows WL and WR until the correlation degree indicating that the pair of images are similar to each other, that is, the correlation calculation. It can be detected as a shift amount of the pair of windows WL and WR until the obtained correlation value reaches the minimum minimum value or the peak value.

  Therefore, the distance calculation unit 2I basically calculates the distance to the object S based on the shift amount x of the windows WL and WR corresponding to the minimum minimum value min of the correlation value calculated by the correlation calculation unit 2E. Calculate. This distance calculation unit 2I is based on the effective minimum value recognized for each distance measurement area M, L, R (see FIG. 4) of the line sensors 1B-L, 1B-R by the minimum value determination unit 2G described later. The distance to the photographing object S is calculated, and the distance to the photographing object S is determined by a predetermined averaging process using the closest distance among the obtained distances as a reference distance.

  Note that the distance calculation unit 2I calculates the distance to the imaging object S in more detail, and therefore corresponds to the shift amounts of the windows WL and WR corresponding to the effective minimum value of the correlation value and the two shift amounts before and after that. An interpolation value calculation of the correlation value is performed based on the correlation value. Based on the shift amount corresponding to the interpolation value, the distance calculation unit 2I determines the distance between the pair of distance measuring lenses 1A-L, 1A-R and the pair of line sensors 1B-L, 1B-R, and the pair of distance sensors. The distance to the object S is calculated with reference to parameters such as the distance between the centers of the line sensors 1B-L and 1B-R and the pitch interval of each cell of the pair of line sensors 1B-L and 1B-R.

  The minimum value determination unit 2G presets the minimum value that maximizes the degree of correlation among the correlation values calculated for each of the distance measurement areas M, L, and R of the line sensors 1B-L and 1B-R. Compared with the reference value SL of the correlation degree. Then, the minimum minimum value smaller than the reference value SL is recognized for each distance measurement area as an effective minimum value effective for the distance measurement calculation. That is, the effective minimum value mM in the central area M, the effective minimum value mL in the left area L, and the effective minimum value mR (not shown) in the right area R are recognized.

  The distance measurement error determination unit 2H performs error determination of the recognized effective minimum value. In this error determination, (1) when there is a difference between the left and right sensor data read from the sensor data storage unit 2D, (2) two or more minimums in which the correlation value calculated by the correlation calculation unit 2E has a small mutual difference. When there is a value, (3) the difference between the minimum minimum value obtained by the correlation calculation by the correlation calculation unit 2E and the correlation values corresponding to the two shift amounts before and after the shift amounts of the windows WL and WR corresponding thereto is small. Made in cases.

  Next, the operation of the distance measuring device of the present invention will be described. FIG. 5 is an operation flowchart of the distance measuring apparatus.

  AF sensor setting processing is performed, and the reflected data from the object to be photographed is taken into the line sensors 1A-L and 1A-R as luminance signals using the autofocus sensor 10 shown in FIG. 1 (S1). The control circuit 1C integrates the luminance signals input from the line sensors 1A-L and 1A-R (S2). The A / D converter 2B converts the integrated luminance signal into 12-bit digital data, and the sensor data converter 2C converts the converted digital data into difference data (S3). Furthermore, the sensor data conversion unit 2C converts the 12-bit difference data into 8-bit data that can obtain high-contrast data that has been enlarged in height difference (S4). Detailed processing of S4 will be described later.

  The difference data converted into 8-bit data is temporarily stored in the sensor data storage unit 2D, and with the window shift control of the window shift unit 2F, the data received by the line sensors 1A-R and 1A-L A correlation value indicating the degree of correlation of the difference data corresponding to the window is calculated for each window shift (S5).

  The minimum determination unit 2G determines a minimum value from a plurality of correlation values calculated for each window shift (S6), and the distance measurement error determination unit 2H determines the error determinations (1) to (3) described above as distance measurement error processing. Based on the above, error determination is performed (S7). Then, as described above, the distance calculation unit 2I calculates the distance to the object to be imaged based on the effective minimum value (S8).

  Next, the sensor data conversion process indicated by S4 in FIG. 5 which is a characteristic part of the present invention will be described. FIG. 6 is an explanatory diagram when one of a plurality of difference data is represented by 12 bits and converted from the 12-bit difference data to 8-bit difference data. FIG. 6A shows the processing when the contrast is low. As shown in FIG. 6B, FIG. 6C, FIG. 7A, and FIG. Indicates processing. This will be specifically described below. As shown in FIG. 8A and the like, D_bit1 is 1 in the 12th bit (bit11) indicating a value equal to or greater than the center value that is the center of the maximum value and the minimum value among a plurality of difference data. Among the ones (in this case, the central value can be regarded as a plus sign), the most significant bit is 1 except for the 12th bit (bit 11), and D_bit0 is a plurality of bits. Among the difference data, the highest bit that is 0 except the 12th bit among the difference data in which the 12th bit indicating the center value or less is 0 (in this case, it can be regarded as a minus sign). Indicates a bit.

  FIG. 6A shows the case where D_bit1 ≧ D_bit0 and D_bit1 = 6, or D_bit1 <D_bit0 and D_bit0 = 6, that is, the 12-bit difference data is in a low contrast state (light and dark are clear). In this case, the 12th bit difference data and the 1st bit to 6th bit data are extracted from the 12 bit differential data and converted to 8 bit data.

  FIG. 6B shows a case where D_bit1 ≧ D_bit0 and D_bit1 = 7 or D_bit1 <D_bit0 and D_bit0 = 7, that is, 12-bit difference data is in a relatively low contrast state (light and dark becomes slightly clear). (The state is higher in contrast than the state shown in FIG. 6A), the 12th bit data and the 2nd to 8th bit data are extracted from the 12-bit difference data. This shows the state when converting to 8-bit data.

  Similarly, FIG. 6C shows a case where D_bit1 ≧ D_bit0 and D_bit1 = 8 or D_bit1 <D_bit0 and D_bit0 = 8, that is, 12-bit difference data is medium among 12-bit difference data. In the case of a contrast state (a state where the clarity of light and darkness is moderate) (a state of higher contrast than the state shown in FIG. 6B), the 12th bit of the 12-bit difference data , And a state when data is converted into 8-bit data by extracting data from the third bit to the ninth bit.

  Similarly, FIG. 7A shows a case where D_bit1 ≧ D_bit0 and D_bit1 = 9, or D_bit1 <D_bit0 and D_bit0 = 9, that is, 12-bit difference data is 12-bit difference data. In the case of a slightly high contrast state (a state in which light and dark are slightly clear) (a state of higher contrast than the state shown in FIG. 6C), the 12th bit of the 12-bit difference data, The state when the data of the 4th to 10th bits is taken out and converted to the data of 8 bits is shown.

  Similarly, FIG. 7B shows a case where D_bit1 ≧ D_bit0 and D_bit1 = 10, or D_bit1 <D_bit0 and D_bit0 = 10, that is, 12-bit difference data out of 12-bit difference data. Is in a high contrast state (a state in which light and dark are clear) (which is a state of higher contrast than the state shown in FIG. 7B), the 12th bit of the 12-bit difference data, and A state when the data of the 5th bit to the 11th bit is extracted and converted to the 8-bit data is shown.

  As described above, the present invention extracts difference data having a maximum value from a plurality of difference data in difference data represented by 12-bit digital data, and the extracted difference data represents difference data by 8 bits. The center when 8 bits are extracted from the difference data represented by 12 bits and the maximum value and the minimum value are represented by 12 bits among a plurality of difference data so that the maximum value can be taken. The difference data represented by the 12 bits is extracted so that the difference data having a value smaller than the center value and the value farthest from the center value can be extracted and the difference between the extracted difference data and the center value can be increased. 8 bits are extracted from the data.

  That is, the difference data having the maximum value is extracted from the difference data represented by predetermined bits (12 bits in the present embodiment), and the highest bit (12 in the present embodiment) is extracted from the extracted difference data. By extracting a predetermined bit (7 bits in the present embodiment) starting from the highest bit to which 1 other than the highest is added and extracting the predetermined bit (12 in the present embodiment) In the difference data represented by (bit), the difference data that is smaller than the center value that is the center of the maximum value and the minimum value represented by a predetermined bit (12 bits in the present embodiment) and is farthest from the center value is extracted. Then, the highest-order bit (the 12th bit in the present embodiment) is extracted from the extracted difference data, and a bit with 0 other than the highest-order bit is specified at the beginning. (7 bits in the present embodiment) can be converted into high contrast data in which the difference in contrast is enlarged. For difference data with a small absolute value, data with a larger absolute value can be obtained. By doing so, the data can be sharpened. That is, in the present invention, the difference in contrast can be increased.

  Next, a specific example is shown. FIGS. 8A and 8B are explanatory diagrams illustrating a specific example when the above-described D_bit1 and D_bit0 are extracted from the difference data calculated from the line sensor. In this figure, the first bit is represented as bit0, the second bit as bit1,..., The 12th bit as bit11.

In the difference data _{a 1} shown in FIG. 8 (a), a 12 bit indicating a higher center value is 1, there is a 1 in 12 bit (bit11) than in a 11 bit (bit10). Further, there is a 0 in the 12-th bit (bit11) of the difference data _{a 2,} there is 1 to 8 bit to 11 bit (bit10) (bit7), there is a 0 in bit 7 (bit6). Also, there is 1 to 12 bit (bit11) of the differential data _{a 3,} there is a 1 in 10 bit (bit9). Also, there is 1 to 12 bit (bit11) of the differential data _{a 4,} there is a 1 in the 9th bit (bit8). In addition, the difference data _{a 5,} a 6, data in a similar manner to such ··· _{a n-2} is formed.

Among the data having 1 in the 12th bit (bit 11), the data having 1 in the most significant bit is the difference data a ₁ and D_bit1 = 10.

Similarly, among the data that 0 to 12 bit (bit11), data that 0 bit at the top will be referred to as difference data _{a 2,} a D_bit0 = 6 here.

Then, comparing D_bit1 and D_bit0, in this example, D_bit1> D_bit0 is established, and 8-bit difference data is generated with the extraction pattern shown in FIG. 7B. In other words, converting from all the differential data a ₁ 12 bit against a _n-2, and the fifth bit by extracting the bits up to 11 bit, 12-bit differential data into 8-bit difference data be able to.

  A similar example is shown in FIG. Here, since D_bit0 = 8 and D_bit1 = 4, data conversion from 12 bits to 8 bits is performed using the extraction pattern shown in FIG.

  By performing such conversion processing, it is possible to perform data conversion to increase the contrast even if the data indicating the contrast of the object to be photographed is small, and without performing reintegration processing even at low contrast, The distance measurement time can be shortened (see FIG. 12C), the photographing time can be shortened, and the distance measurement accuracy can be improved. FIG. 9 is an explanatory diagram showing a specific example of the effect.

  FIG. 9 shows the case of the present invention when the reintegration process is not performed by the conventional technique, when the reintegration process is performed by the conventional technique. FIG. 9A is a diagram showing a state when difference data having a high contrast is input. In this case, the difference data is not limited to the conventional method or the method of the present invention. There is not much change, and it is in a high contrast state. As the contrast decreases, for example, as shown in FIGS. 9 (d) and 9 (e), in the method of the conventional technique, when the difference data has a small contrast, reintegration processing is performed. It takes a long distance measurement time (see FIG. 12). Furthermore, even if the reintegration process is performed, the contrast may remain small (FIG. 9E). In this case, the accuracy of distance measurement cannot be improved by the conventional method. On the other hand, in the method of the present invention, even when the contrast of the difference data is small (FIG. 9 (e)), the conversion process can be performed to increase the difference data as described above. Difference data with high contrast can be obtained.

  Hereinafter, a detailed operation when converting difference data with low contrast into difference data with high contrast will be described.

  FIG. 10 is a detailed operation flow diagram when the detailed sensor data conversion process of S4 in FIG. 5 is performed, and the operation for determining the contrast when the difference data of the present invention is converted into high contrast data. FIG.

  First, D_bit0 = 6 and D_bit1 = 6 are initially set in a register unit (not shown) provided in the sensor data conversion unit 2C and held (S10). And the difference data which consists of one 12 bits in the difference data obtained by the sensor data conversion part 2C is read (S11). It is determined whether or not the read difference data consisting of 12 bits is bit11 = 1 (that is, the 12th bit is 1) (S12). Here, it is determined whether the maximum value is smaller or larger than the center value. If the center value is considered as the origin, it is determined whether the value is positive or negative.

  If the difference data is bit11 = 1, it is then determined whether the difference data is bit10 = 1 (whether the 11th bit is 1) (S13). If an affirmative determination is made, D_bit1 = 10 is set in the register unit and held in the register unit (S14), and the process proceeds to step S36 of the data conversion process in FIG.

  If a negative determination is made in S13, it is determined whether or not the difference data is bit9 = 1 (whether the 10th bit is 1) (S15). If an affirmative determination is made, it is further determined whether or not D_bit <9. If an affirmative determination is made, D_bit1 = 9 is set in the register unit and held in the register unit (S17), and the next difference data is stored. If there is (S24), the difference data is read (S11). If a negative determination is made, if there is the next difference data (S24) without specifically holding the information, the difference data is read (S11).

  If a negative determination is made in S15, it is determined whether the difference data is bit8 = 1 (whether the 9th bit is 1) (S18). If an affirmative determination is made, it is further determined whether or not D_bit1 <8 (S19). If an affirmative determination is made, D_bit1 = 8 is set and held in the register unit (S20), and the next difference data is available. If this is the case (S24), the difference data is read (S11). When a negative determination is made, if there is the next difference data (S24) without particularly holding the information, the difference data is read (S11).

  If a negative determination is made in S18, it is determined whether the difference data is bit7 = 1 (whether the 8th bit is 1) (S21). If an affirmative determination is made, it is further determined whether or not D_bit1 <7 (S22). If an affirmative determination is made, D_bit1 = 7 is set and held in the register section (S23), and the next difference data is available. If this is the case (S24), the difference data is read (S11). When a negative determination is made, if there is the next difference data (S24) without particularly holding the information, the difference data is read (S11).

  If a negative determination is made in S21, it is determined whether all of the difference data has been read (S24), and if not all have been read, the next difference data is read (S11).

  Returning to S12, if the difference data is bit11 = 0 in S12, it is determined whether the difference data is bit10 = 0 (whether the 11th bit is 0) (S25). When an affirmative determination is made, D_bit0 = 10 is set in the register unit and held (S26), and the process proceeds to step S36 of the data conversion process described later.

  If a negative determination is made in S25, it is determined whether the difference data is bit9 = 0 (whether the 10th bit is 0) (S27). If an affirmative determination is made, it is determined whether or not D_bit0 <9 (S28). If an affirmative determination is made, D_bit0 = 9 is set and held in the register unit (S29), and the next difference data is stored. If there is (S24), the difference data is read (S11). When a negative determination is made, if there is the next difference data (S24) without particularly holding the information, the difference data is read (S11).

  If a negative determination is made in S27, it is determined whether the difference data is bit8 = 0 (whether the 9th bit is 0) (S30). If an affirmative determination is made, it is determined whether or not D_bit0 <8 (S31). If an affirmative determination is made, D_bit0 = 8 is set and held in the register unit (S32), and the next difference data is stored. If there is (S24), the difference data is read (S11). When a negative determination is made, if there is the next difference data (S24) without particularly holding the information, the difference data is read (S11).

  If a negative determination is made in S30, it is determined whether the difference data is bit7 = 0 (whether the 8th bit is 0) (S33). If an affirmative determination is made, it is determined whether or not D_bit0 <7 (S34). If an affirmative determination is made, D_bit0 = 7 is set and held in the register unit (S35), and the next difference data is stored. If there is (S24), the difference data is read (S11). When a negative determination is made, if there is the next difference data (S24) without particularly holding the information, the difference data is read (S11).

  If a negative determination is made in S33, the difference data extracted here is determined that there is no data that should be the object in determining the contrast. If there is next difference data (S24), the difference data is read out. (S11).

  Then, S11 to S35 are repeated until reading of all the difference data is completed (S24).

  As described above, the processing from S11 to S35 determines the level of the contrast of the luminance signal of the photographing object from the difference data. For example, when D_bit1 = 10 or D_bit0 = 10 is set and held, the contrast of the luminance signal from the object to be photographed is high, and data conversion processing suitable for that case is performed in FIG. . On the contrary, when D_bit1 = 6 or D_bit0 = 6 is set and held, the contrast of the luminance signal from the object to be photographed is low, and data conversion processing for increasing the contrast is performed in FIG. ing.

  Next, the operation after the above-described contrast determination according to FIG. 10 is performed will be described. FIG. 11 is an operation flowchart when converting 12-bit difference data into 8-bit difference data.

  As described above, D_bit1 and D_bit0 are set in the register unit. First, the two are compared to determine which is larger (S36). If it is determined that D_bit1 is large, it is determined whether D_bit1 = 10 (S37). If the determination is affirmative, the 12th bit and the 5th to 11th bits of the differential data represented by all 12 bits are extracted and converted as 8-bit data (S38).

  If a negative determination is made in S37, it is determined whether D_bit1 = 9 (S39). If an affirmative determination is made here, the 12th bit and the 10th bit from the 4th bit of all the difference data represented by 12 bits are extracted and converted to 8 bit data (S40).

  If a negative determination is made in S39, it is determined whether D_bit1 = 8 (S41). If an affirmative determination is made here, the 12th bit and the 9th to 9th bits of all the difference data represented by 12 bits are extracted and converted as 8-bit data (S42).

  If a negative determination is made in S41, it is determined whether D_bit1 = 7 (S43). If an affirmative determination is made here, the 12th bit, the 2nd bit to the 8th bit of all the difference data represented by 12 bits are extracted and converted as 8 bit data (S44).

  If a negative determination is made in S43, the 12th bit and the 1st to 7th bits of all the difference data represented by 12 bits are extracted and converted as 8-bit data (S54).

  Returning to S36, if it is determined that D_bit0 is large, it is determined whether D_bit0 = 10 (S50). If an affirmative decision is made, as shown in S38, the 12th bit and the 5th to 11th bits of the differential data represented by all 12 bits are extracted and converted as 8-bit data (S38).

  If a negative determination is made in S50, it is further determined whether D_bit0 = 9 (S51). If an affirmative decision is made here, as shown in S40, the 12th bit and the 4th to 10th bits of the total difference data represented by 12 bits are extracted and converted as 8-bit data (S40).

  If a negative determination is made in S51, it is further determined whether D_bit0 = 8 (S52). If an affirmative decision is made here, as shown in S42, the 12th bit and the 3rd to 9th bits of the total difference data represented by 12 bits are extracted and converted into 8-bit data (S42).

  If a negative determination is made in S52, it is further determined whether D_bit0 = 7 (S53). If an affirmative decision is made here, the 12th bit, the 2nd bit to the 8th bit of the total difference data represented by 12 bits are extracted and converted as 8-bit data (S44).

  If a negative determination is made in S53, as shown in S54, the 12th bit and the 7th bit from the 1st bit of all the difference data represented by 12 bits are extracted and converted as 8-bit data (S54).

  As described above, the contrast is determined from the difference data generated from the luminance signal of the object to be photographed, and appropriate 8 bits are extracted from the 12-bit difference data according to the degree of contrast, and converted into 8-bit data. By converting, low contrast difference data can be converted to high contrast difference data. As a result, it is possible to calculate appropriate data when measuring the distance without performing recalculation processing of data conversion when the data received by the light receiving sensor has low luminance, and to shorten the distance measurement time. In addition, the shooting time can be shortened (see FIG. 12C), and the ranging accuracy at low contrast can be improved.

  In this embodiment, 12-bit data is converted to 8-bit data, and five types of bit extraction are performed according to the degree of contrast. However, the present invention is not limited to this. Accordingly, six or more types of bit extraction methods may be employed, and a device that converts to 7 bits or 9 bits according to the degree of enlargement rate of data conversion may be used.

It is an external view of the camera apparatus provided with the distance measuring device of the present invention. It is a block block diagram of the ranging apparatus of this invention. It is explanatory drawing which shows the process which produces | generates the difference data of the data input into the line sensor. It is a schematic diagram which shows a mode by performing the shift operation by a window shift part. It is an operation | movement flowchart which performs a ranging process in the ranging apparatus of this invention. It is explanatory drawing when obtaining high contrast data from difference data which is low contrast, (a) is explanatory drawing in the case of low contrast, (b) is explanatory drawing in the case of slightly low contrast, (c) is contrast. It is explanatory drawing when the grade of is medium. It is explanatory drawing when obtaining high contrast data from difference data which is low contrast, (a) is explanatory drawing in the case of a little high contrast, (b) is explanatory drawing of high contrast. It is explanatory drawing which shows a mode that D_bit1 and D_bit0 are extracted from difference data, (a) is a specific explanatory drawing in the case of d_bit1> d_bit0, (b) is a specific explanatory drawing in the case of d_bit1 <d_bit0. . It is explanatory drawing which compares the effect in the ranging device of this invention, (a) is explanatory drawing in case of contrast high, (b) is explanatory drawing in case of medium contrast, (c) is medium contrast. (D) is an explanatory diagram when the contrast is medium and small, and (e) is an explanatory diagram when the contrast is small. It is an operation | movement flowchart which judges the contrast at the time of converting the difference data into high contrast data in the distance measuring device of this invention. It is an operation | movement flowchart at the time of converting the difference data in the distance measuring device of this invention into high contrast data. It is a comparison figure of the process using a prior art, and the process using this invention, (a) is a figure which showed the normal process in a prior art, (b) is a reintegration in a prior art. The figure which showed the process when doing, (c) is the figure which showed the process when using this invention. It is explanatory drawing which shows the fault at the time of using a prior art, (a) is the figure which showed the process at the time of high brightness and high contrast, (b) showed the process at the time of high brightness and low contrast. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Line sensor unit, 2 ... Distance measuring operation apparatus, 1A-L ... Lens, 1A-R ... Lens, 1B-L ... Line sensor, 1B-L ... Line sensor, 1C ... Line sensor control circuit, 2A ... Line sensor Control unit, 2B ... A / D conversion unit, 2C ... sensor data conversion unit, 2D ... sensor data storage unit, 2E ... correlation calculation unit, 2F ... window shift unit, 2G ... minimum determination unit, 2H ... measurement Distance error determination unit, 2I ... distance calculation unit, 10 ... autofocus sensor window, 11 ... lens, 12 ... shutter button

Claims (5)

A pair of light-receiving sensors for distance measurement composed of a plurality of light-receiving elements that receive reflected light from the object to be photographed;
A / D conversion means for converting luminance data of reflected light received by each of the pair of light receiving sensors into a pair of digital data;
Using the pair of digital data converted by the A / D conversion means, the digital data is converted into a predetermined bit by calculating a difference in luminance data between adjacent light receiving elements in the plurality of light receiving elements. Differential data conversion means for converting into a pair of differential data for correlation calculation;
High-contrast data conversion for converting a pair of difference data converted by the difference data conversion means into a pair of high-contrast data in which the difference in height of contrast is expanded in the luminance data of reflected light received by the plurality of light receiving elements Means,
Calculating means for calculating the distance to the object to be photographed using a pair of high contrast data converted by the high contrast data converting means ;
The high-contrast data conversion means extracts differential data having a maximum value from differential data represented by predetermined N bits, extracts the highest-order bit from the extracted differential data N-bits and other than the highest-order data By extracting (M−1) bits (M <N) with the highest bit attached with 1 as the head, it is converted to high contrast data in which the difference in contrast is expanded,
The calculation means is a pair of high contrast data obtained by the conversion by the high contrast data conversion means, and is applied to the high contrast data divided for each distance measurement area unit to be subjected to correlation calculation. For each distance area unit, the pair of high contrast data ranging areas is calculated using a pair of windows, and the degree of correlation of a part of the pair of high contrast data is calculated, and the pair of windows are located within the distance measuring area. The correlation is calculated every time the quantitative shift is performed, and the distance to the object to be imaged is calculated based on the distance measurement area having a high correlation obtained according to the result of the calculation and the shift amount of the window. A distance measuring device characterized by that . A pair of light-receiving sensors for distance measurement composed of a plurality of light-receiving elements that receive reflected light from the object to be photographed;
A / D conversion means for converting luminance data of reflected light received by each of the pair of light receiving sensors into a pair of digital data;
Using the pair of digital data converted by the A / D conversion means, the digital data is converted into a predetermined bit by calculating a difference in luminance data between adjacent light receiving elements in the plurality of light receiving elements. Differential data conversion means for converting into a pair of differential data for correlation calculation;
High-contrast data conversion for converting a pair of difference data converted by the difference data conversion means into a pair of high-contrast data in which the difference in height of contrast is expanded in the luminance data of reflected light received by the plurality of light receiving elements Means,
Calculating means for calculating the distance to the object to be photographed using a pair of high contrast data converted by the high contrast data converting means;
The high-contrast data conversion means calculates difference data closest to the center value smaller than the center value that is the center between the maximum value and the minimum value expressed by N bits among the difference data expressed by predetermined N bits. Extracting and extracting the highest order bit from the extracted differential data N bits and extracting (M−1) bits (M <N) starting from the bit with 0 other than the highest order. , Converted to high-contrast data with an enlarged contrast difference ,
The calculation means is a pair of high contrast data obtained by the conversion by the high contrast data conversion means, and is applied to the high contrast data divided for each distance measurement area unit to be subjected to correlation calculation. For each distance area unit, the pair of high contrast data ranging areas is calculated using a pair of windows, and the degree of correlation of a part of the pair of high contrast data is calculated, and the pair of windows are located within the distance measuring area. Each time a quantitative shift is performed, the correlation degree is calculated, and the distance to the object to be photographed is calculated based on the distance measurement area having a high degree of correlation obtained according to the result of the calculation process and the shift amount of the window. A distance measuring device characterized by that . The image processing apparatus further includes a determination unit that determines the degree of contrast from the difference data, and the high-contrast data conversion unit converts the degree of enlargement of the contrast level according to the degree of contrast determined by the determination unit. distance measuring apparatus according to claim 1 or 2, characterized in. An input step for inputting brightness data of reflected light from the object to be photographed through a pair of light receiving sensors for distance measurement composed of a plurality of light receiving elements;
A first conversion step for converting the input luminance data into a pair of digital data;
Using the pair of converted digital data , a difference between luminance data of every other adjacent light receiving elements in the plurality of light receiving elements is calculated, whereby the digital data is paired with a difference for correlation calculation of a predetermined bit. A second conversion step for converting to data;
A third conversion step for converting the pair of converted difference data into a pair of high contrast data in which the difference in height of the contrast is enlarged in the luminance data of the reflected light received by the plurality of light receiving elements;
A calculation step of calculating a distance to the object using the pair of converted high contrast data ,
The third conversion step extracts differential data having the maximum value from the differential data represented by predetermined N bits, extracts the highest-order bit from the extracted differential data N-bit, and other than the highest By extracting (M−1) bits (M <N) with the highest bit attached with 1 as the head, it is converted to high contrast data in which the difference in contrast is expanded,
In the calculation step, a pair of high contrast data obtained by the conversion in the third conversion step, and the high contrast data divided for each distance measurement area unit to be subjected to correlation calculation, the measurement is performed. For each distance area unit, the pair of high contrast data ranging areas is calculated using a pair of windows, and the degree of correlation of a part of the pair of high contrast data is calculated, and the pair of windows are located within the distance measuring area. Each time a quantitative shift is performed, the correlation degree is calculated, and the distance to the object to be photographed is calculated based on the distance measurement area having a high degree of correlation obtained according to the result of the calculation process and the shift amount of the window. A distance measuring method characterized by that .   An input step for inputting brightness data of reflected light from the object to be photographed through a pair of light receiving sensors for distance measurement composed of a plurality of light receiving elements;
  A first conversion step for converting the input luminance data into a pair of digital data;
  Using the pair of converted digital data, a difference between luminance data of every other adjacent light receiving elements in the plurality of light receiving elements is calculated, whereby the digital data is paired with a difference for correlation calculation of a predetermined bit. A second conversion step for converting to data;
  A third conversion step for converting the pair of converted difference data into a pair of high contrast data in which the difference in height of the contrast is enlarged in the luminance data of the reflected light received by the plurality of light receiving elements;
  A calculation step of calculating a distance to the object using the pair of converted high contrast data,
In the high contrast data conversion step, difference data that is smaller than the center value that is the center between the maximum value and the minimum value that are represented by N bits and that is closest to the center value among the difference data that is represented by predetermined N bits. Extracting and extracting the highest order bit from the extracted differential data N bits and extracting (M−1) bits (M <N) starting from the bit with 0 other than the highest order. , Converted to high-contrast data with an enlarged contrast difference,
  In the calculation step, a pair of high contrast data obtained by the conversion in the third conversion step, and the high contrast data divided for each distance measurement area unit to be subjected to correlation calculation, the measurement is performed. For each distance area unit, the pair of high contrast data ranging areas is calculated using a pair of windows, and the degree of correlation of a part of the pair of high contrast data is calculated, and the pair of windows are located within the distance measuring area. Each time a quantitative shift is performed, the correlation degree is calculated, and the distance to the object to be photographed is calculated based on the distance measurement area having a high degree of correlation obtained according to the result of the calculation process and the shift amount of the window. A distance measuring method characterized by that.

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