JP4336892B2 - Imaging apparatus, printing apparatus, and printing system - Google Patents

Description

  The present invention relates to an imaging apparatus, a printing apparatus, and a printing system, and more particularly to a technique for printing an image captured by an imaging apparatus using a printing apparatus that is applied to the imaging apparatus.

  Conventionally, the luminance information from the shadow portion to the highlight portion of the subject is acquired, and then all the luminance information from the minimum to the maximum is determined based on the maximum / minimum luminance of the acquired luminance information with a predetermined gradation (8 bits). There has been proposed a digital camera that performs gradation conversion so that it can be recorded with a digital camera (Patent Document 1). In Patent Document 1, the gradation conversion conditions are recorded together with the image data, and the image is reproduced with reference to the gradation conversion conditions at the time of reproduction, thereby reproducing the background or the like as necessary or suppressing the reproduction. It is described to do.

Also proposed is an image processing device that sets the dynamic range using the information of the area when there is an area where the gradation is likely to be lost in the image, and corrects the contrast of the image using the set dynamic range. (Patent Document 2).
Japanese Patent Laid-Open No. 11-196291 JP 2003-169231 A

  The digital camera described in Patent Document 1 can record gradation-converted image data of a predetermined number of bits (8 bits) from the shadow portion to the highlight portion, thereby enabling almost all subjects to be recorded. Brightness information can be recorded, and gradation conversion conditions etc. can be recorded together with image data, so that images can be reproduced with reference to gradation conversion conditions during reproduction, but the brightness of the main subject is optimal There is a problem that it cannot be played automatically.

  Japanese Patent Application Laid-Open No. 2004-228561 changes the gradation of an image based on the maximum reference luminance and the luminance of the main image portion (that is, depending on whether the main image portion is on the highlight portion side or the shadow portion side). However, in this case as well, exposure control is performed based on the main subject. Therefore, there is a problem that the brightness reproduction of the main subject cannot be optimally performed.

  Similarly, there is no description regarding brightness reproduction of the main subject in Patent Document 2, and the image processing apparatus described in Patent Document 2 cannot be automatically reproduced so that the brightness of the main subject is optimized. is there.

  The present invention has been made in view of such circumstances, and provides an imaging apparatus, a printing apparatus, and a printing system that can achieve both reproduction of a highlight part and a shadow part and brightness reproduction of a main subject. Objective.

  In order to achieve the above object, an imaging apparatus according to claim 1 includes a first exposure value calculation unit that calculates a first exposure value at which a main subject has an optimum exposure amount, and a luminance center of a shooting scene as a latitude center. The second exposure value calculating means for calculating a second exposure value to be substantially matched, and the first image for correcting the main subject to an appropriate brightness together with an image picked up based on the second exposure value. And a recording means for recording exposure information including the exposure value.

  That is, by imaging the subject based on the second exposure value, the latitude of the imaging device can be used effectively, and the exposure information (corrects the main subject to an appropriate brightness) together with the captured image. Exposure information including the first exposure value for recording) is recorded, and the exposure information can be used to reproduce the brightness of the main subject so as to be optimal.

  2. The image pickup apparatus according to claim 1, wherein when the luminance range of the picked-up image exceeds a predetermined latitude, the contrast compression for compressing the contrast of the image so as to be within the latitude. And recording means for recording the contrast compression information indicating the degree of the contrast compression together with the image compressed by the contrast compression means. As a result, even when a subject with a wide dynamic range is imaged, all the image information can be recorded from the highlight portion to the shadow portion, and at the time of reproduction, the contrast compression information is used to restore the original wide dynamic range image. Can be stretched.

  According to a third aspect of the present invention, in the image pickup apparatus according to the second aspect, the contrast compression unit compresses only a highlight portion and a shadow portion of the luminance range of the image. As a result, the gradation information of the halftone of the image is not lost during the contrast compression, and the reproducibility of the image is improved.

  4. The imaging apparatus according to claim 1, wherein when the luminance range of the captured image is smaller than a predetermined latitude, the contrast of the image is negatively compressed so as not to exceed the latitude. In addition, the recording means records contrast compression information indicating the degree of the contrast compression together with the image compressed by the contrast compression means. Thereby, the latitude of the imaging device can be used effectively.

  5. The imaging device according to claim 1, wherein a reading unit that reads an image and exposure information recorded by the recording unit and the read image and the exposure information are used for the imaging device. The image processing apparatus further includes gradation correction means for correcting the main subject so as to have appropriate brightness, and display means for displaying an image corrected by the gradation correction means. This makes it possible to display an image with gradation correction so that the lightness reproduction of the main subject is optimized using the exposure information recorded together with the image.

  According to a sixth aspect of the present invention, there is provided a print system according to any one of the first to fourth aspects, an input unit that inputs an image and exposure information recorded in the recording unit, and an input unit that receives the input image and exposure information. A printing apparatus comprising: gradation correction means for correcting the main subject so as to have an appropriate brightness, and printing means for printing an image on a print medium based on the image corrected by the gradation correction means. And is composed of.

  A printing apparatus constituting the printing system inputs an image and exposure information recorded by the imaging device, and generates an image for printing from the input image by using exposure information input simultaneously with the image. The gradation of the image is corrected so that the brightness reproduction of the subject is optimal, and the image is printed on the print medium based on the corrected image. As a result, an image is printed on the print medium so that the brightness of the main subject is optimized. Note that since the input image includes all image information from the highlight portion to the shadow portion, a print image can be obtained in which no jump occurs in the highlight portion or no shadow portion occurs.

  According to a seventh aspect of the present invention, there is provided a print system according to any one of the second to fourth aspects, an input unit that inputs an image recorded in the recording unit, exposure information, and contrast compression information, and the input image. Contrast expansion means for expanding the image based on the input contrast compression information, gradation correction means for correcting the main subject to have an appropriate brightness based on the expanded image and the exposure information, and the floor The printing apparatus includes a printing unit that prints an image on a printing medium based on the image corrected by the tone correction unit.

  That is, the printing apparatus constituting the printing system further includes contrast expansion means as compared with the printing apparatus according to claim 6. When the contrast compression information is input by the input means, the contrast compression information is used. Thus, the input image is expanded to the original wide dynamic range image.

  A printing apparatus according to an eighth aspect constitutes the printing system according to the sixth or seventh aspect.

  According to the present invention, a subject is imaged based on the second exposure value that substantially matches the luminance center of the shooting scene to the latitude center, and together with the captured image, a main subject for correcting the main subject to an appropriate brightness. Since exposure information including the exposure value (first exposure value) of the subject is recorded, the reproduction of the highlight portion and the shadow portion and the lightness reproduction of the main subject are performed based on the recorded image and the exposure information. Image reproduction or print output can be performed in a compatible manner.

  Preferred embodiments of an imaging apparatus, a printing apparatus, and a printing system according to the present invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an embodiment of an internal configuration of an imaging apparatus according to the present invention.

  An image pickup apparatus 10 shown in the figure is a digital camera that electronically picks up a still image or a moving image of a subject. As an image pickup unit (image pickup means), an optical system 11 including a photographing lens and a diaphragm, and an image pickup element are used. A certain CCD 12 is provided. The optical system 11 includes an iris motor driver 18 that drives an iris motor that displaces a diaphragm provided in the optical system, and an AF motor driver 19 that drives an autofocus (AF) motor that displaces a focusing lens. Is connected.

  On the output side of the CCD 12, a CDS analog decoder 13, a white balance amplifier 14, a γ correction circuit 15, a dot sequential circuit 16, and an A / D converter 17 are provided. A signal is output. An electronic volume (EVR) 22 is connected to the white balance amplifier 14 so that the gain of the white balance amplifier 14 is controlled. The output of the A / D converter 17 is transmitted to the main memory 21 via the memory controller 20, and the captured image data of the subject is stored in the main memory 21.

  Further, brightness adjusting means 23, contrast adjusting means 24, release switch 25, and operating means such as a power button, a shooting mode selection dial, a shooting / playback mode selection switch, a back switch, a menu / OK switch, and a multi-function cross key. 26, contrast optimization means 27, multi-pattern photometry means 28, AE (Automatic Exposure) condition determination means 29 for the main subject, and AE condition determination means 30 for the optimum contrast. A central processing unit (CPU) 31 is provided as control means for controlling each part of the apparatus, and the iris motor driver 18, AF motor driver 19, electronic volume 22, brightness adjustment means 23, contrast adjustment means 24, release switch. 25, operating means 26, contrast optimizing means 27, multi-pattern photometric means 28, AE condition determining means 29 for the main subject, AE condition determining means 30 for the optimal contrast, and data bus 32.

  The contrast optimizing unit 27 determines whether the highlight and the shadow are within the latitude when the AE control is performed based on the brightness of the main subject. If the contrast is not within the latitude, the optimum contrast is determined. When the AE condition is determined by the AE condition determining means 30 for the AE and the AE control is performed according to the determined AE condition, if the highlight and the shadow do not fall within the latitude, the contrast is further compressed via the contrast adjusting means 24. Let the coefficient be determined.

  The multi-pattern photometric unit 28 divides image data for one screen stored in the main memory 21 into, for example, 64 areas of 8 × 8, and obtains a photometric value EV (Exposure Value) value for each of these divided areas. The AE condition determining means 29 for the main subject obtains the photometric value EVev of the divided area to which the main subject belongs. The divided area to which the main subject belongs can be designated on the liquid crystal monitor by the photographer or can be automatically designated by recognizing the face of the person.

  The AE condition determining means 30 for the optimum contrast obtains a photometric value EVcont for the optimum contrast. Here, the photometric value EVcont is an intermediate value between the maximum photometric value EVmax and the minimum photometric value EVmin among the 64 photometric values EV obtained by the multi-pattern photometric means 28.

  The brightness adjusting unit 23 outputs an exposure correction value so that the photometric value EVcont substantially matches the latitude center. Further, the contrast adjusting unit 24 obtains a contrast compression coefficient so that the highlight and the shadow are slightly inside from the latitude end. Further, CONT (= standard contrast × contrast compression coefficient) is obtained from the standard contrast and the contrast compression coefficient.

  The data bus 32 includes a CPU 31, a memory controller 20, a main memory 21, a contrast optimization unit 27, and a multi-pattern photometry unit 28, a compression / decompression unit 33, an MPEG encoder / decoder 34, a YC signal creation unit 35, An external memory interface 38, a communication interface 40, an LCD driver 42, and audio input / output means 44 are connected.

  The compression / decompression unit 33 performs image data compression processing and decompression processing by the JPEG method or the like. The MPEG encoder & decoder 34 encodes MPEG moving image data and decodes MPEG compressed and encoded moving image data. The YC signal creation unit 35 separates and generates the luminance signal Y and the color difference signals RY and BY for generating an NTSC video signal. The YC signal creation unit 35 is followed by a color conversion unit 36 for converting the ratio of the luminance signal Y and the color difference signals RY and BY from 4: 4: 4 to 4: 2: 2, and NTSC video. An NTSC encoder 37 that generates and outputs a signal is provided.

  The compression / decompression unit 33, the MPEG encoder & decoder 34, the YC signal creation unit 35, the color conversion unit 36, and the NTSC encoder 37 may be constituted by dedicated signal processing circuits, or the CPU 31 performs software processing. It is also possible to configure with a function to be performed or a signal processing circuit such as a DSP having a function.

  A liquid crystal monitor (LCD) 43 is connected to the LCD driver 42, and a through movie of the subject to be photographed, a recorded image after photographing, various status displays, a setting screen, and the like are displayed on the screen of the LCD 43. ing. A speaker 45 and a microphone 46 are connected to the audio input / output means 44, and various operation sounds at the time of shooting and the like are reproduced and output, and sound signals at the time of moving image shooting are input.

  In the imaging apparatus 10 configured as described above, an image of a subject is formed on the imaging surface of the CCD 12 by the optical system 11 and subjected to photoelectric conversion. The imaging signal output from the CCD 12 is subjected to correlated double sampling by the CDS analog decoder 13 to cancel the noise component, and then the white level of the color image signal is adjusted by the white balance amplifier 14. Then, γ correction is performed by the γ correction circuit 15, A / D converted by the A / D converter 17 through the dot sequential circuit 16, and output as digital image data. This digital image data is stored in the main memory 21 via the memory controller 20.

  The digital image data is displayed on the screen of the LCD 43 as a subject image being photographed. The photographer shoots a still image or a moving image of the subject by pressing the release switch 25 and turning it on while viewing the subject image. The image data after shooting is compressed by the compression / decompression unit 33 or MPEG compression / encoded by the MPEG encoder & decoder 34, and the external recording medium 39 or the communication interface 40 via the external memory interface 38. The image is sent to an external device 41 such as a personal computer, and a captured image is recorded. The captured image data is converted into an NTSC video signal through a YC signal creation unit 35, a color conversion unit 36, and an NTSC encoder 37, and is output as video.

  Next, imaging operations including automatic exposure control by the imaging apparatus 10 having the above configuration will be described in detail with reference to the flowchart of FIG.

  In FIG. 2, first, the CPU 31 sets contrast compression coefficient = 1.0 (step S10), and then determines whether or not the switch S1 is pressed (step S12). The shutter button has a switch S1 that is turned on when the shutter button is half-pressed to prepare for photographing such as focus lock and photometry, and a switch S2 that is turned on when the shutter button is fully pressed to capture an image. When the switch S1 is pressed, the following shooting preparations are made.

  That is, the CPU 31 performs focusing by contrast AF (step S14). In the focusing operation by contrast AF, first, the focus lens is moved over a range corresponding to the range from the nearest to the infinity via the AF motor driver 19, the image data in between is taken in, and the integrated value of the high-frequency component of the image data at each lens position (AF evaluation value) is calculated. Then, the lens position where the AF evaluation value is maximized is calculated, and the focus lens is moved to that lens position.

  When focusing is completed, the multi-pattern photometry unit 28 obtains a photometric value EV for each of the 64 divided areas based on the image data for one screen, and the AE condition determining unit 29 for the main subject performs photometry of the divided region to which the main subject belongs. A value EV is obtained, and EVev is temporarily stored in the internal memory as this photometric value EV = EVev (steps S16 and S18). Further, EVcont is temporarily stored in the internal memory as EVcont = EVev (step S20).

  Next, the contrast optimizing unit 27 determines whether or not the highlight and shadow of the brightness range of the image are within the latitude (step S22). If the highlight and shadow of the luminance range are within the latitude, the process jumps to step S32 and the contrast compression coefficient is stored in the internal memory. The contrast compression coefficient stored in this case is 1.0 which is initially set in step S10.

  On the other hand, when the highlight and shadow of the luminance range do not fall within the latitude, the AE condition determining means 30 for the optimum contrast sets the photometric value EVcont so that the highlight and the shadow are equidistant from the latitude midpoint. The photometric value EVcont (= (EVmax + EVmin) / 2) between the maximum photometric value EVmax and the minimum photometric value EVmin among the 64 photometric values EV for each of the divided areas obtained by the multi-pattern photometric unit 28). Obtained (step S24). The photometric value EVcont stored in step S20 is updated with the photometric value EVcont for the optimum contrast thus obtained (step S26).

  For example, when the main subject is photographed with a black background, the brightness (1) (photometric value EVev) of the main subject is on the highlight side as shown in FIG. Therefore, when the AE control is performed based on the photometric value EVev of the main subject, the shadow does not fit within the latitude as shown in FIG.

  Similarly, when the main subject is photographed with backlight, the brightness (1) (photometric value EVev) of the main subject is on the shadow side as shown in FIG. Therefore, when AE control is performed based on the photometric value EVev of the main subject, highlights do not fall within the latitude as shown in FIG.

  Therefore, when the highlight and the shadow do not fit in the latitude, the photometric value EVcont is stored for AE control based on the photometric value EVcont obtained in step S24. When the AE control is performed based on the photometric value EVcont, in the case of the scene shown in FIG. 3, the main subject is brightened by ΔEV (= EVev−EVcont) (FIG. 3C), and in the case of the scene shown in FIG. The main subject becomes darker by ΔEV (= EVcont−EVev) (FIG. 4C).

  Returning to FIG. 2, when AE control is performed based on the photometric value EVcont, it is determined whether highlights and shadows in the luminance range of the image fall within the latitude (step S28). If the highlight and shadow of the brightness range are within the latitude, the process jumps to step S32.

  On the other hand, when the highlight and shadow of the luminance range do not fit within the latitude, the contrast adjusting means 24 obtains a contrast compression coefficient that makes the highlight and shadow slightly inside the latitude end (step S30).

  FIG. 5 shows the case of backlight and high contrast, and FIG. 5A shows how the highlight and shadow do not fit within the latitude. FIG. 5B shows the case where the contrast is compressed so as to be within the latitude.

  In step S30, CONT (= standard contrast × contrast compression coefficient) is obtained from the standard contrast and the contrast compression coefficient. The contrast compression coefficient obtained in this way is stored in the internal memory (step S32).

  Thereafter, the CPU 31 determines whether or not the switch S2 is pressed (step S34). When the switch S2 is pressed, the CPU 31 determines the shooting EV value based on EVev or EVcont and CONT obtained in step S30. The charge accumulation time (electronic shutter) in the CCD 12 is controlled by the shutter speed and aperture value obtained from the photographing EV value, and the aperture provided in the optical system 11 is controlled to image (exposure) (step S36). .

  Then, the captured image data in which EVev, EVcont, the EV value used in photographing, and the contrast compression coefficient are embedded is created and stored in the external memory 39 (step S38). Note that exposure information such as EVev, EVcont, EV value used in shooting, and a contrast compression coefficient can be written in the header of an image file.

  Also, as shown in FIG. 6, when the highlight and the shadow do not fit within the latitude ((A) in FIG. 6), the shadow portion is set to 0 when the contrast compression is performed to fit within the 8-bit (256) latitude. The contrast may be compressed to ˜30, the highlight portion may be compressed to 225 to 255, and the contrast of the halftone may not be compressed (see FIGS. 6B and 6C).

  FIG. 7 is a block diagram showing an embodiment of the internal configuration of the printing apparatus according to the present invention.

  A printing apparatus 50 shown in the figure is installed at a store or the like and is used by general users, and is particularly suitable for printing an image captured by the imaging apparatus 10.

  The CPU 51 in the printing apparatus 50 includes a memory controller 53, a recording medium reader / writer 55, a printing unit 56, a contrast expansion unit 57, a contrast compression unit 58, a brightness level shift unit 59, and a RAW development engine 64 via a bus 52. , And RGB / YMC (K) conversion means 65.

  The CPU 51 is connected to a touch panel 60, a display driver 61 for driving the display 63, and a charging unit 62.

  Image data recorded on recording media of various digital cameras is read by a recording media reader / writer 55 and temporarily stored in the work memory 54 via the memory controller 53.

  The contrast expansion unit 57 and the contrast compression unit 58 extend or compress the contrast by multiplying the image data by the reciprocal of the contrast compression coefficient read together with the image data. The brightness level shift means 59 shifts the level of the image data so that the brightness of the main subject becomes an optimum value, and shifts by a value obtained by subtracting the EV value photographed by photographing from the photometric value EVev of the main subject. . It should be noted that the shift amount of the image data in the shadow portion or the highlight portion may be gradually reduced as it becomes the shadow end or the highlight end.

  The touch panel 60 is arranged on the display 63, and functions as an input unit for touching and selecting an image to be printed from the images displayed on the display 63, or designating the number of prints. The billing means 62 performs, for example, cash collection by a coin machine and change processing according to the number of prints.

  When the image data read from the recording medium is RAW data (unprocessed image data output from an image sensor such as a CCD), the RAW development engine 64 performs linear matrix processing and white balance processing on the RAW data. Then, data that can be output to the display 63 or the like is generated by performing a synchronization process or the like.

  The RGB / YMC (K) conversion means 65 converts R, G, B data subjected to various image processing into Y, M, C, (K) (yellow, magenta, cyan, (black)) data. The converted Y, M, C, (K) data is output to the printing means 56.

  The printing means 56 employs, for example, a TA (Thermo Autochrome) system as a printing system, and heats a color photographic paper (hereinafter referred to as “TA paper”) having C, M, and Y coloring layers. It is colored and fixed by irradiation with light of a predetermined wavelength, and has means for conveying TA paper, a thermal head, a fixing lamp, and the like. When printing a color image on TA paper, the TA paper is first transported and the thermal head is controlled by Y data to develop the yellow layer of the TA paper, and then the yellow color is fixed by the fixing lamp. Color development of the magenta layer and cyan layer of TA paper is similarly performed based on the M data and C data, thereby printing a color image on the TA paper. Although the printing means 56 of this embodiment is a TA printer, the present invention is not limited to this, and the present invention can also be applied to other types of printers such as other thermal printers and inkjet printers.

  Next, the printing operation by the printing apparatus 50 configured as described above will be described in detail below with reference to the flowchart of FIG.

  In FIG. 8, first, image data is read from the recording medium loaded in the recording medium reader / writer 55 and temporarily stored in the work memory 54 via the memory controller 53 (step S50). The CPU 51 determines whether or not the read image data is “contrast optimization” print data (step S52). If it is normal print data, the process proceeds to step S54, and if it is “contrast optimization” print data. Jumps to step S60. In the case of the image data recorded by the image pickup apparatus 10 described in FIG. 1 (when EVev, EVcont, EV value used in photographing, and contrast compression coefficient are embedded in the header of the image file), “ Discrimination as “contrast optimization” print data.

  In step S54, it is determined whether or not the contrast of the print data is less than a certain value. If contrast <constant value, the process proceeds to step S56, and if contrast ≧ constant value, the process jumps to step S58. In step S56, the contrast of the image data is expanded by the contrast expansion means 57 so that the contrast becomes a constant value.

  In step S58, the RGB / YMC (K) conversion means 65 converts the R, G, B data into Y, M, C, (K) data for printing and outputs the data to the printing means 56. The printing means 56 prints an image on photographic paper based on the input Y, M, C, (K) data (step S76).

  On the other hand, when the read image data is determined to be “contrast optimization” print data, EVev, EVcont, EV value used in photographing, and contrast compression coefficient recorded in correspondence with the image data are read (steps). S60).

  The contrast expansion unit 57 multiplies the image data by the reciprocal of the read contrast compression coefficient to expand the contrast (step S62).

  Subsequently, the brightness level shift means 59 translates the brightness of the image data by a value obtained by subtracting the EV value obtained by photographing from the photometric value EVev of the main subject so that the brightness of the main subject becomes the optimum value. Correction is performed (step S64).

  Thereafter, it is determined whether or not the highlight side of the corrected image data exceeds the dynamic range (step S66), and if it exceeds, the image data brighter than the main subject is compressed so as to be within the dynamic range. (Step S68). Similarly, it is determined whether or not the shadow side of the corrected image data exceeds the dynamic range (step S70), and if it is over, image data darker than the main subject is compressed so as to be within the dynamic range. (Step S72).

  The R, G, and B data subjected to gradation correction in this way are converted into Y, M, C, and (K) data for printing by the RGB / YMC (K) conversion means 65 (step S74), and the printing means 56. Is output. The printing means 56 prints an image on photographic paper based on the input Y, M, C, (K) data (step S76).

  FIG. 9 is a graph showing gradation conversion characteristics when gradation conversion is performed on the image data shown in FIG.

  In the image data shown in FIG. 3C, the main subject becomes brighter by ΔEV (= EVev−EVcont) as described above, but gradation correction is made so that the main subject becomes darker by ΔEV as shown in FIG. By doing so, it is possible to correct so that the brightness of the main subject becomes optimum. Note that similar gradation correction is performed when image data is output to the LCD 43 of the imaging apparatus 10.

  FIG. 10 is a graph showing gradation conversion characteristics when gradation conversion is performed on the image data shown in FIG. 4C during printing.

  In the image data shown in FIG. 4C, the main subject is darkened by ΔEV (= EVev−EVcont) as described above, but the gradation correction is performed so that the main subject is brightened by ΔEV as shown in FIG. By doing so, it is possible to correct so that the brightness of the main subject becomes optimum.

  FIG. 11A shows image data in which the shadow portion and the highlight portion are subjected to contrast compression (see FIG. 6C).

  The image data in which the shadow portion and the highlight portion have been subjected to contrast compression has the shadow portion and the highlight portion based on the contrast compression coefficients (in this case, the contrast compression coefficients set for the shadow portion and the highlight portion, respectively) at the time of printing. The light part is subjected to contrast expansion. FIG. 11B shows image data that has undergone contrast expansion.

  The contrast-expanded image data is subsequently subjected to gradation correction so that the brightness of the main subject becomes optimum as shown in FIG. In FIG. 11D, the image data is shifted so that the main subject becomes bright. Note that the shift amount is reduced for the image data on the shadow side and the highlight side (see FIG. 10).

  The highlight-side image data that exceeds the dynamic range (in this example, image data of 225 or more) is contrast-compressed so that it falls within 225 to 255, and the shadow side that exceeds the dynamic range. The image data (image data of 30 or less in this example) is subjected to contrast compression so as to be within 0 to 30 (see FIG. 11E).

  FIG. 12 is a graph showing another embodiment in which image data is created during gradation-corrected printing from contrast-compressed image data.

  In FIG. 12, the gradation of the image data subjected to contrast compression indicated by a one-dot chain line is subjected to contrast expansion based on the contrast compression coefficient to become a dynamic range gradation indicated by a dotted line. For example, when the image data subjected to contrast compression has an 8-bit gradation, the image data is expanded to image data having a 10-bit gradation using a contrast compression coefficient.

  Subsequently, gradation correction is performed so that the brightness of the main subject is shifted by ΔEV (= EVev−EVcont) based on EVev and EVcont stored together with the image data. The solid line in FIG. 12 indicates the input / output characteristics after gradation correction.

  The image data indicated by the solid line may be output to the printing unit, or may be output to the printing unit after the shadow portion and highlight portion are contrast-compressed and corrected to 8-bit data as described above. .

  In this embodiment, together with the image data, a photometric value EVcont intermediate between the maximum photometric value EVmax and the minimum photometric value EVmin of the photometric value EVev of the main subject and the photometric value EV of each divided area subjected to multi-pattern photometry. However, the present invention is not limited to this. For example, instead of the photometric value EVcont, the maximum photometric value EVmax and the minimum photometric value EVmin may be stored. In addition, it is only necessary to store exposure information necessary for correction.

FIG. 1 is a block diagram showing an embodiment of an internal configuration of an imaging apparatus according to the present invention. FIG. 2 is a flowchart used for explaining the photographing operation including the automatic exposure control by the imaging apparatus. FIG. 3 is a diagram showing AE control when the main subject is photographed with a black background. FIG. 4 is a diagram showing AE control when the main subject is photographed with backlight. FIG. 5 is a diagram used for explaining contrast compression. FIG. 6 is a diagram used to explain the case where the shadow portion and the highlight portion are subjected to contrast compression. FIG. 7 is a block diagram showing an embodiment of the internal configuration of the printing apparatus according to the present invention. FIG. 8 is a flowchart used to explain the printing operation by the printing apparatus. FIG. 9 is a graph showing gradation conversion characteristics when gradation conversion is performed on the image data shown in FIG. FIG. 10 is a graph showing gradation conversion characteristics when gradation conversion is performed on the image data shown in FIG. 4C during printing. FIG. 11 is a diagram showing a state of gradation conversion when image data for printing is created from image data in which the shadow portion and highlight portion are subjected to contrast compression. FIG. 12 is a graph showing another embodiment in which image data is created during gradation-corrected printing from contrast-compressed image data.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Imaging device, 11 ... Optical system, 12 ... CCD, 23 ... Brightness adjustment means, 24 ... Contrast adjustment means, 25 ... Release switch, 27 ... Contrast optimization means, 28 ... Multi-pattern photometry means, 29 ... Main subject AE condition determining means for 30 ... AE condition determining means for optimum contrast 31, 51 ... Central processing unit (CPU), 39 ... Recording media, 43 ... Liquid crystal monitor (LCD), 55 ... Recording media reader / writer, 56 ... Print means 57 ... Contrast expansion means 58 ... Contrast compression means 59 ... Brightness level shift means 65 ... RGB / YMC (K) conversion means

Claims (8)

First exposure value calculating means for calculating a first exposure value at which the main subject has an optimum exposure amount;
Second exposure value calculation means for calculating a second exposure value for causing the luminance center of the shooting scene to substantially coincide with the latitude center;
Recording means for recording exposure information including the first exposure value for correcting the main subject to an appropriate brightness together with an image captured based on the second exposure value;
An imaging apparatus comprising:   When the luminance range of the captured image exceeds a predetermined latitude, the image recording apparatus further includes a contrast compression unit that compresses the contrast of the image so as to be within the latitude, and the recording unit compresses the contrast by the contrast compression unit. The imaging apparatus according to claim 1, wherein contrast compressed information indicating a degree of the contrast compression is recorded together with the image that has been recorded.   The imaging apparatus according to claim 2, wherein the contrast compression unit compresses only a highlight portion and a shadow portion of a luminance range of the image.   When the luminance range of the captured image is smaller than a predetermined latitude, the image recording apparatus further includes a contrast compression unit that negatively compresses the contrast of the image so as not to exceed the latitude, and the recording unit includes the contrast compression unit. The imaging apparatus according to claim 1, wherein contrast compressed information indicating a degree of the contrast compression is recorded together with an image compressed by contrast.   Reading means for reading out the image and exposure information recorded by the recording means, gradation correction means for correcting the main subject to have an appropriate brightness based on the read image and exposure information, and the gradation 5. The imaging apparatus according to claim 1, further comprising display means for displaying an image corrected by the correction means. An imaging device according to any one of claims 1 to 4,
Input means for inputting the image and exposure information recorded in the recording means; gradation correction means for correcting the main subject to have an appropriate brightness based on the input image and exposure information; A printing apparatus comprising printing means for printing an image on a printing medium based on the image corrected by the tone correction means;
A printing system composed of An imaging device according to any one of claims 2 to 4,
Input means for inputting the image recorded in the recording means, exposure information and contrast compression information, contrast expansion means for expanding the input image based on the input contrast compression information, the expanded image and the exposure Gradation correction means for correcting the main subject to have an appropriate brightness based on information, and print means for printing an image on a print medium based on the image corrected by the gradation correction means. A printing device;
A printing system composed of   A printing apparatus constituting the printing system according to claim 6 or 7.

Images