JP2773081B2 - Contour extraction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to an electrophotographic image forming apparatus that records image information using a laser beam or the like, and is suitable for use in an outline extracting apparatus. More particularly, the present invention relates to a contour extraction device that prevents white spots.

BACKGROUND OF THE INVENTION Image forming apparatus For example, as is well known, an electrophotographic copying machine for monochrome images has an image forming body (a photosensitive drum functioning as an image carrier) and a predetermined image forming body. This is an apparatus that forms an electrostatic latent image, develops and fixes this using a developer such as toner, and performs image information copying.

Such an image forming apparatus is equipped with a microcomputer, and is capable of performing even relatively complicated image processing. As shown in FIG. 42, in this image processing, there is an image processing in which only the outline of an image such as a character is left and the inside thereof is outlined and copied.

To perform this image processing, it is necessary to extract a contour signal corresponding to the contour of the image. FIG. 43 shows an example of a contour extraction device used for this contour extraction. Such a process of extracting the inside of an image is hereinafter referred to as a blanking process. Therefore, FIG. 43 shows a conventional example of the number of hollowing-out processes for contour extraction.

As shown in the figure, the hollowing-out processing circuit 500 has delay elements 541 and 543 for delaying two pixels and a delay element 542 for delaying two pixels and four images.

Then, regarding the image data obtained from the third line,
The image data delayed by 1, 3, and 5 pixels is supplied to an edge detection circuit 550 in the main scanning direction, and an edge signal of the image in the main scanning direction is formed. The edge detection circuit 550 is
AND circuit 55 for ANDing image data four pixels apart
1 and an exclusive OR circuit 552 that performs an exclusive OR operation on the AND output and the image data of the pixel of interest.

Similarly, the image data of the first and fifth lines is supplied to the edge detection circuit 560 in the sub-scanning direction, and an edge signal of the image in the sub-scanning direction is formed. As described above, the edge detection circuit 560 includes an AND circuit 561 for ANDing image data separated by five lines, and an exclusive OR circuit 562 for performing an exclusive OR operation on the AND output and the image data of the pixel of interest. You.

Then, when the edge signals in the main and sub-scanning directions are combined, an edge signal of the image is obtained. Therefore, or
565 are provided.

For convenience of explanation, an example of a hollowing-out process in a portion where the background is sharp as shown in FIG.

With respect to the image as shown in FIG. 44 (a), the internal signals D1 to D6 at the edges are as shown in FIG. 44 (b) with reference to the horizontal lines l1 to l6. When a process of extracting only the edge portion in the scanning direction is performed, contour signals (edge signals) E1 to E6 as shown in FIG. FIG. 2B illustrates two pixels as the edge width. Among these edge signals, the edge signal corresponding to the end point q is E4.

An edge signal in the sub-scanning direction is obtained by similar processing. The internal signals D1 to D6 are as shown in FIG. 45 (b). When the processing for extracting only the edge portion in the sub-scanning direction from the internal signals D1 to D7 is performed, the edge signal as shown in FIG. E2 'to E4' are obtained.

Therefore, if the edge signals E1 to E6 in FIG. 44 and the edge signals E2 'to E5' in FIG. 45 are logically ORed for the corresponding lines, the total in the main and sub-scanning directions as shown in FIG. Are generated as the edge signals E2 + E2 ', E3 + E3',.

[Problem to be Solved by the Invention] If the above-described hollow processing circuit 500 is used, image data of only the outline of the image can be obtained.
It can be copied as a blank image as shown in the figure.

However, in the hollow image, particularly at a portion where the background portion is sharp, that is, at a portion indicated by a dotted line in FIG. 42, the extracted outline is not continuous, and a so-called white portion occurs. This is the edge signal corresponding to the end point q shown in FIG.
This is because, as is clear from E5 + E5 ', the contour of the end point q is not prompted as a contour.

In view of the above, the present invention solves such a problem, and proposes a contour extraction device capable of correctly extracting a contour from any image.

Means for Solving the Problems In order to solve the above-described problems, the contour extraction device according to the present invention uses a unit of a pixel of an image obtained by scanning an image acquisition system in a main scanning direction and a sub-scanning direction. Device for extracting the contour information of the image from the image data to be
First edge detecting means for detecting edges at both ends of the image scanned in the main scanning direction, and detecting edges at both edges of the image scanned from the image data of the image scanned in the sub-scanning direction. A second edge detecting means;
And second edge detecting means (hereinafter, edge detecting circuits 510, 5
20) (hereinafter also referred to as OR circuits 525 and 526) for calculating the output of the image in the main scanning direction and detecting both edges of the image in the main scanning direction and the both ends of the image in the sub-scanning direction. When edge detection is performed, an equal number of predetermined pixels before and after a pixel that specifies an edge of an image in the main scanning direction and the sub-scanning direction are extracted.

[Operation] According to the present invention, when performing both edge detection of an image in the main scanning direction and both edge detection of an image in the sub scanning direction,
The same number is extracted for predetermined pixels before and after a pixel specifying an edge of an image in the main scanning direction and the sub-scanning direction.

With this configuration, both edges of the image can be captured with good reproducibility by the same number of pixels before and after a specific pixel of the image in the main scanning direction and the sub-scanning direction. Can be extracted as a contour.

In other words, if pixels before and after the contour, for example, one pixel are extracted so as to include the rising portion and the falling portion of the image signal, the edge signal in the main scanning direction is as shown in FIG. 2 (c). The edge signal in the sub-scanning direction is as shown in FIG.

When they are combined, as shown in FIG. 3 (d), edge signals corresponding to the end point q and the outline of the image branched from the end point q are extracted. Therefore, if an image is copied with respect to this edge signal, there will be no discontinuous portion of the outline, and no white spots will occur.

[Embodiment] Hereinafter, a case where an example of the contour extracting apparatus according to the present invention is applied to an electrophotographic copying machine used as the above-described image forming apparatus will be described in detail with reference to FIG.

4 and 5 show a schematic configuration of a circuit diagram of an image forming apparatus to which the present invention can be applied, and FIG. 6 shows a schematic configuration of a mechanical system thereof.

In FIG. 4, the image forming apparatus 10 includes a scanner unit.
10A, an image processing unit 10B and a printer unit 10C.

The scanner unit 10A refers to a series of processing systems for converting an optical image related to image information of a document obtained by optically scanning into an electric signal.

The printer unit 10C is capable of outputting an image signal (eg, image data subjected to PWM or multi-value processing) output from the image signal unit or binary print data supplied from the outside. It refers to a processing system until recording as a visual image.

In this example, an electrophotographic recording method using an image forming body (photosensitive drum) is adopted as the printer unit 10C, and a semiconductor laser is used as a light source for forming the electrostatic latent image. Therefore, the printer unit 10C is configured as an electrophotographic laser printer.

The image processing 10B is a processing unit for performing appropriate image processing on an input image signal, and includes a blanking process. In addition to the hollowing out processing, image processing such as scaling processing, filtering processing, shading processing, and PWM processing are performed.

FIG. 6 shows an example of such a mechanical part of the digital copying machine constructed as described above.

The description starts with the scanner unit 10A. By turning on the copy button provided in the digital copier,
The upper original 1 is optically scanned by the optical system.

This optical system includes a carriage 84 provided with a light source 85 and a reflection mirror 86, and V mirrors 89 and 89 '.

A halogen lamp is used as a light source. A commercially available green fluorescent lamp may be used instead of the halogen lamp. In this case, the fluorescent lamp is turned on and driven by a high-frequency power supply of about 40 kHz to prevent flicker. Further, it is necessary to maintain the temperature with a heater using a posistor in order to maintain a constant temperature of the tube wall or to promote warm-up.

A standard white plate 97 is provided on the upper surface of the left end of the platen glass 81. This is for normalizing an image signal (white signal) obtained by optically scanning the standard white plate 97 to a standard white signal.

The carriage 84 and the V mirrors 89, 89 'are caused to travel on a slide rail (not shown) in a predetermined direction at a predetermined speed by a stepping motor 90.

An optical image (image information) obtained by irradiating the original 1 with the light source 85 is guided to the optical information conversion unit 12 via the reflection mirror 87 and the V mirrors 89 and 89 '. The optical information conversion unit 12 includes a lens 13 and a CCD 11 on which an optical image is formed, and converts the optical image into an electric signal (image signal).

The image signal is subjected to various types of image processing by the image processing unit 10B, and then output to the printer unit 10C.

The printer unit 10C has a deflector 935. As the deflector 935, a deflector including an optical deflector using crystal or the like may be used in addition to a galvanometer mirror, a rotating polygon mirror, or the like. The laser beam modulated by the image signal is supplied to the deflector 93
Deflection scanning is performed by 5.

When deflection scanning is started, beam scanning is detected by a laser beam index sensor (not shown),
Beam modulation by the image signal is started. The image signal includes the image information (copy data) of the document 1 described above,
Print data is selectively used.

The modulated beam is scanned by the charger 121 on the image forming body (photosensitive drum) 110 to which uniform charging is applied.

Here, the main scanning by the laser beam and the image forming body 11
The electrostatic latent image corresponding to the image signal is formed on the image forming body 110 by the sub-scanning by the rotation of 0.

This electrostatic latent image is developed by a developing device 123 containing black toner. A predetermined bias voltage from a high-voltage power supply is applied to the developing device 123. A black and white image is formed by development.

On the other hand, the recording paper P fed from the paper feeding device 141 via the feed roll 142 and the timing roll 143 is conveyed onto the surface of the image forming body 110 in a state where the timing is synchronized with the rotation of the image forming body 110. Is done. Then, the black toner image is transferred onto the recording paper P by the transfer pole 130 to which the high voltage is applied from the high voltage power supply, and is separated by the separation pole 131.

The separated recording paper P is conveyed to the fixing device 132 and subjected to a fixing process to obtain a monochrome image.

The image forming body 110 after the transfer is cleaned by the cleaning device 126, and is prepared for the next image forming body process.

In the cleaning device 126, in order to facilitate collection of the toner cleaned by the blade 127,
A predetermined DC voltage is applied to a metal roll 128 provided on 127. The metal roll 128 is arranged on the surface of the image forming body 110 in a non-contact state.

After the cleaning, the blade 127 is released from the pressure contact.However, at the time of the release, an auxiliary cleaning roller 129 is further provided to remove unnecessary toner remaining, and the roller 129 is rotated in the opposite direction to the image forming body 110, and the pressure is released. By doing so, the unnecessary toner is sufficiently cleaned and removed.

The printer unit 10C is an electrophotographic printer using a semiconductor laser as described above.

FIG. 7 particularly shows a main part of a deflection scanning system using a semiconductor laser.

The laser beam emitted from the semiconductor laser 931 is mirror 9
Polygon 93 consisting of octahedral rotating polygon mirror via 42,943
It is incident on 5. The laser beam is deflected by the polygon 935, and is irradiated on the surface of the image forming body 110 through an f-θ lens 944 for imaging.

945 and 946 are cylindrical lenses for correcting the tilt angle.

The laser beam is scanned by the polygon 935 at a constant speed on the surface of the image forming body 110 in a predetermined direction a.

The f-θ lens 944 is used to equalize the beam position on the image forming body 110.

A primary image is formed on the photoconductor by a normal negative / positive reversal phenomenon with respect to the electrostatic latent image created as described above.

 This is shown in FIG.

This figure shows the change in the surface potential of the image forming body 110, and the case where the charging polarity is this positive is taken as an example. PH indicates an exposed portion of the image forming body, DA indicates a non-exposed portion of the image forming body, and DUP indicates a rising portion of the potential caused by the positively charged toner T1 adhering to the exposed portion PH during development.

The image forming body 110 is uniformly charged by a charger,
It becomes a constant positive surface potential E. Example An image exposure using a laser as an exposure source is given, and the potential of the exposed portion PH decreases according to the light amount.

The electrostatic latent image thus formed is developed by a developing device to which a positive bias substantially equal to the surface potential E of the unexposed portion has been applied. As a result, the positively charged toner adheres to the exposed portion PH having a relatively low potential, and a toner image is formed.

In the area where the toner image is formed, the potential increases by DUP due to the attachment of the positively charged toner T1, but usually does not become the same as that of the unexposed portion DA.

Next, the image is transferred onto a recording sheet, and is further fixed by heating or pressing to obtain recorded image data. In this case, the toner and charges remaining on the surface of the image forming body are cleaned and used for the next image forming body.

As a method of forming a latent image for forming an image, in addition to electrophotography, a method of forming an electrostatic latent image by injecting electric charge directly onto the image forming body using a multi-needle electrode or the like, or a method of forming a magnetic latent image by using a magnetic head. A method of forming an image or the like can be used.

 FIG. 5 is a specific example of the image processing unit 10B.

The image signal is supplied to the A / D converter 20 to be converted into a digital signal of a predetermined number of bits, in this example, 8 bits. Shading correction is performed simultaneously with A / D conversion. The shading correction circuit 21 is, as shown in FIG.
A line memory 22 is provided. In this example, image signals for 16 lines are stored, and an average of the image signals in an averaging circuit 23 is used as a reference signal for shading correction.

The digital image signal that has been subjected to shading correction is supplied to a filtering processing circuit 24, where a filtering process according to the image content is performed.

For example, in the case of a character image, its resolution (for example, MT
F)
A photographic image is subjected to a filtering process for smoothing an image signal in order to improve moire.

This filtering process can be realized by, for example, a 3 × 3 convolution filter. Fig. 10 shows an example.

FIG. 2 shows a case where the filter is configured as a cross filter. FIG. 2A shows a filter for resolution correction, and FIG. 2B shows a filter for smoothing. Which filter to use is specified externally. This designation signal can also be generated automatically.

The numerical values shown in FIG. 10 are filter coefficients, but this is an example.

The MTF is calculated by the following equation from the signal level y of the white signal and the signal level x of the black signal.

MTF = (y−x) / (y + x) × 100 (%) The reason for performing the MTF correction is that the aperture size of the CCD 11 increases in the sub-scanning direction, including the deterioration of sharpness in a transmission system such as a lens. In some cases, the MTF degradation in the sub-scanning direction is more pronounced in the sub-scanning direction than in the main scanning direction because the signal is obtained by integrating the optical signal in the sub-scanning direction. is there.

By performing the MTF correction process, it is possible to correct the character jump and crush.

The image data that has been subjected to the filtering processing is subjected to extraction / deletion / painting processing for a specific area in the signal processing means 300.

Since these processes and the above-described filtering process are both performed inside or outside the designated region, in order to perform these processes, the region detection circuit 25 needs to detect the designated region.

The specified area can be detected using a position-designated paper (blank) as shown in Fig. 11.
2 is performed on the basis of the marker M written above. Therefore, before the original 1 is fully scanned, the position designation paper 2 is placed on the original platen.
Preliminary scanning is performed on the image sensor 81, thereby detecting an area. The area may be specified in a rectangular shape as shown in the figure, or may be specified in an arbitrary shape as shown in FIG.

Since the area detection can employ various means, detailed description thereof will be omitted, but in this example, as shown in FIGS. 13A and 13B,
The next area signal Qi (FIG. 8E) is formed from the area signal Qi-1 detected immediately before and the marker signal Ri. Therefore, as shown in FIG. 14C, the logical product of the two is calculated, and then an internal signal of the marker is created based on the AND output (D in FIG. 14). The logical sum of the internal signal and the marker signal Ri is calculated to generate a region signal Qi on the i-th line as shown in FIG.

The region signal Q thus formed is extracted / erased /
The signal is supplied to the signal processing means 300 for performing the filling. At this time, instructions inside / outside the marker area are followed.

FIG. 14 shows an example of the signal processing means 300. An image signal supplied to a terminal 301 is supplied to a selector 302 and converted into image data corresponding to a processing designation signal such as image deletion. Therefore, a control signal forming circuit 310 is provided in association with the selector 302.

As shown, the control signal forming circuit 310 includes three NAND circuits 311 to 313 and a NAND circuit 31 to which the output is supplied.
4 and the area signals R are commonly supplied to the NAND circuits 311 to 313 on the input side in addition to the corresponding processing designation signals.

In “painting”, the output of the NAND circuit 311 for designating all black processing is supplied to the input side of the selector 302 together with the image data, and the selector 302 is controlled by the control signal output from the NAND circuit 314.

In the figure, when the control signal is “H”, the input is selected on the b side.

If "extraction" processing is designated as the processing designation signal, image data will be output only while this is obtained. Similarly, in "erase" processing, image data output is prevented only during that time. Then, in the process designation of “full filling”, a signal of “1” (predetermined DC voltage) is output as image data instead of the input image data.

The image signal and the area signal R that have been subjected to the predetermined signal processing are supplied to the scaling processing circuit 30 and are subjected to enlargement / reduction processing as required.

The scaling process is performed by electrical processing for interpolating image signals in the main scanning direction, and is performed by mechanical processing for changing the scanning speed of the scanner unit 10A in the sub-scanning direction.

 The scaling ratio is 50-400%, and it is a vertical and horizontal independent scaling format.

The reason why the area signal R is also supplied to the scaling processing circuit 30 is that it is necessary to scale the area signal R in accordance with the scaling factor.

The image signal subjected to the scaling process is then processed by the tint block processing circuit 400.
Supplied to One type of tint block is shading.

The reason why the copy-forgery-inhibited pattern is applied at the stage when the scaling process is completed is to make the pitch of the designated copy-forgery-inhibited pattern fixed, even after the scaling process.

An example of the tint block pattern is shown in FIGS. 15 (1) to (7).

In order to output such pattern data, normally the 16th
As shown in the figure, these pattern data are stored in the copy-forgery-inhibited pattern data ROM 401, and these are externally selected.

Therefore, a column address counter 402 and a row address counter 403 are provided for the copy-forgery-inhibited pattern data ROM 401. For example, the column address of the copy-forgery-inhibited pattern data ROM 401 is specified by a counter output incremented by a signal corresponding to the A3 size. Clock CK synchronized with Pell
The row address of the copy-forgery-inhibited pattern data ROM 401 is designated by the counter output incremented by.

The copy-forgery-inhibited pattern data (8 × 8 matrix pattern data) obtained by the address command is logically ORed with the image data in the OR circuit 404 to obtain the image data after the copy-forgery-inhibited pattern.

The area signal R and the tint block designating signal are supplied to an AND circuit 405, and the tint block data ROM 401 is chip-selected by its output.

As a result, as shown in FIG. 17, when a copy-forgery-inhibited pattern designation signal is obtained, the copy-forgery-inhibited pattern copy data RO
The tint block pattern data of M401 becomes valid.

The repetition of address designation for the copy-forgery-inhibited pattern data ROM 401 is determined by the repetition cycle of the copy-forgery-inhibited pattern.

A dither process may be performed to enhance halftone of image data before proceeding to the tint block process.

 The image data after the copy-forgery-inhibited pattern is transferred to a blanking process.

FIG. 1 shows an example of a hollowing-out processing circuit 500 for preventing the white spot, in which image data for a contour signal is symmetrically extracted inside and outside an edge to create an edge signal.

In this example, an example in which equal pixels are extracted one pixel at a time across an edge will be described, but the number of pixels to be extracted is arbitrary.
Also, a case where image data (that is, quaternary data) is composed of 2 bits for convenience of description is shown. Since one pixel is composed of 8 bits, the blanking process is executed in parallel for each bit.

First, the image data is supplied to a 5-line memory 35 shown in FIG. 5, from which the original image data and the image data delayed by 1, 3 and 5 lines are output.

Each of the image data is processed by a blanking processing circuit 500 shown in FIG.
Supplied to FIG. 44 (a) is illustrated as an original image.
This is shown again in FIG. 2 (a).

In the case of the original picture of FIG. 2 (a), each of the lines l1 to l6
Thus, a contour internal signal as shown in FIG.
The contour internal signal is delayed by two pixels in delay elements 503 and 504 each constituted by a shift register or the like, and the three delayed image data are detected by the edge detection circuit 51 in the main scanning direction.
0 is supplied to the exclusive OR circuits 511 and 512 to form an edge signal shown in FIG.

Therefore, if the image data delayed by two pixels from the current image data is taken as the image data of interest, the above-described processing has resulted in the edge signals each having one pixel width sandwiching the edge.

Next, the image data of the first line and the fifth line are supplied to the corresponding delay elements 501, 502, 505, and 506, and are respectively delayed by two pixels from the current image data. The image data of 1, 3, and 5 lines (FIG. 3 (b)) output from these are input to the edge detection circuit in the sub-scanning direction for each bit.
520.

Since the edge detection circuit 520 is also formed of an exclusive OR circuit, an edge signal shown in FIG. This edge signal also has a width of one pixel before and after the edge of the original image.

Therefore, if the OR signals of the edge signal in the main scanning direction and the edge signal in the sub-scanning direction are respectively ORed by the OR circuits 525 and 526, an overall edge signal as shown in FIG. 3D is generated.

In this comprehensive edge signal, as will be clear from verification of several lines from the line 13 where the end point q exists, an edge signal related to the edge including the end point q is continuously generated.

In this manner, if the original image is subjected to the centering process by forming an edge signal so as to sandwich the edge, white spots do not occur even when the background portion is an acute angle like the end point q as shown in FIG. . It is preferable to express the contour with a width of about 2 pels at both ends of the edge portion (a total of 4 pels).

The output of the hollow processing circuit 500 is subjected to image inversion processing in the inversion circuit 40, and then supplied to the gamma correction circuit 45. The gamma correction circuit 45 is provided to ensure consistency between the scanner unit 10A and the printer unit 10C.

FIG. 18 shows various characteristics between the scanner unit 10A and the printer unit 10C. The first quadrant shows the recording characteristics of the printer unit 10C, the second quadrant shows the density characteristics after copying, and the third quadrant shows the scanner characteristics. The conversion characteristic of the unit 10A is shown, and the IV quadrant shows the gamma correction characteristic.

Therefore, the optical density of the original 1 is converted into a predetermined image signal by the scanner unit 10A (quadrant III), and a predetermined gamma characteristic is given to this image signal (quadrant IV). Is pulse-width modulated (PWM) (IV quadrant), and the image is recorded according to the PWM modulated output, so that the copy density is determined by this recording characteristic (I quadrant).

As a result, the relationship between the density of the original and the density actually copied is as shown in the characteristics of the second quadrant.

Now, as is apparent from the characteristics of the second and fourth quadrants,
It is better to make the gamma characteristic steep as shown in FIG. This is because a low density area having an optical density of about 0.1 to 0.4 is important for character reproduction.

On the other hand, it is better to make the gamma characteristic slower for a photographic part. This is because tone reproduction is emphasized.
Usually, γ = 1 is selected. Otherwise, jumping in the low-density portion and crushing in the high-density portion occur.

Even for the same character portion, various specific curves can be selected for the gamma characteristic. The following measures can be taken.

In this example, a case where the gamma characteristic is set by automatically detecting the density of the document and a case where the gamma characteristic is manually set are exemplified.

First, the filtered image data is supplied to an automatic density setting circuit (EE circuit) 50 for density detection.

For example, in order to determine the type of an image by obtaining the spread of density information, preliminary scanning is performed to create a density histogram of the document 1 (see FIG. 19). The maximum density, the minimum density, and the background level of the document 1 are obtained from the density histogram, and a selection signal for selecting a gamma correction curve suitable for the document is generated based on the maximum density, the minimum density, and the background signal. Thereafter, it is supplied to the gamma correction circuit 45.

On the other hand, the gamma correction curve is also selected by the manual selection signal supplied to the terminal 57.

The gamma-corrected image data is subjected to mirror image processing in the mirror image processing circuit 60 when there is an external designation, and thereafter the selector 70 outputs the image data (8 bits) and the 1 sent from the external print data controller 65. Bit binary data is selected.

The binary data is print data, for example, data generated by a Japanese word processor is input. Therefore, the image forming apparatus 10 has a printing function for the external print data controller 65 in addition to a copying function for the original 1.

Since the image data is 8 bits and the print data is 1 bit, A0 to A6 of the input ports A0 to A7 of the selector 70 are grounded at the time of print data.

 Which function is selected depends on the external designation.

The selected image data (8 bits or 1 bit) is supplied to the PW modulation circuit 600 shown in FIG.

In this example, the gradation processing is exemplified by luminance modulation instead of the area gradation processing. Therefore, 8-bit image data is
After being converted to an analog signal by the D / A converter 601, the generation circuit
Analog comparison is performed by reference signals such as a triangular wave and a ramp wave output from the 602. The reference signal is repeated for each pixel (FIG. 21A).

When the reference signal is a triangular wave, when the level of the image data to be referred to is as shown in FIG.
When a semiconductor laser (to be described later) is modulated with this PWM modulation output as shown in FIG. 4C, the light emission level (luminance level) as shown in FIGS. Has been subjected to luminance modulation (intensity modulation).

 The reason for employing such intensity modulation will be described below.

First, when recording is performed with a normal laser power (1.0 to 3.0 mW), curves of La to Lc (γ
Curve) becomes very steep. This is a binary recording, and is a recording format in which the width of the black dot changes with the PWM output. However, in order to actually change the black dot width by the PWM output, the cycle of the reference signal needs at least two dots or more.

There is no particular problem if a reference signal having a period of 2 dots or more is used for a gradation image, but if a character image is to be reproduced, line jumps become conspicuous, and character quality deteriorates. For this reason, in this example, both the character image and the gradation image can be sufficiently reproduced even by the reference signal of one dot cycle.

To do so, the curve Ld in FIG.
It is sufficient that the γ curve approaches γ = 1 as shown in FIG. This can be achieved by lowering the laser power of the semiconductor laser 931 constituting the developing means than usual, for example, to a laser power of about 0.5 mW (see the broken line curve in FIG. 23).

In order to further bring γ closer to 1, one or both of the charging means and the developing means may be controlled as desired. In this example, both the charging voltage VH applied to the charger 121 for the image forming body 110 and the developing bias voltage VB supplied to the developing device 123 are adjusted to be higher than usual.

A typical example is shown in Table 1, and the recording characteristics at that time are shown by a solid line curve in FIG.

 Table 1 VH VL laser power Normal 600V 480V 2mW Example 700V 580V 0.5mW FIG. 24 shows an example of the printer unit 10C.

In the figure, a semiconductor laser 931 has a drive circuit 932
Is supplied to the drive circuit 932 as a modulation signal, and the laser signal is internally modulated by the modulation signal. The laser drive circuit 932 is controlled by a control signal from the timing circuit 933 so as to be driven only in the horizontal and vertical effective area sections. A signal indicating the light amount of the laser beam is fed back to the laser drive circuit 932,
The drive of the laser is controlled so that the light amount of the beam becomes constant.

The scanning start point of the laser beam deflected by the octahedral polygon 935 is detected by the index sensor 936, which converts the index signal into a voltage signal by the I / V amplifier 937. The timing is supplied to a CPU 251 (FIG. 25) which controls the system, and the timing of optical scanning is controlled.

Reference numeral 934 denotes a polygon motor drive circuit.
The off signal is supplied from the timing circuit 933.

The various devices or circuits described above are all controlled by the first and second control units 200 and 250 as shown in FIG. The second control unit 250 will be described.

The second control unit 250 mainly controls the scanner unit 10A and the peripheral devices, and 251 is a microcomputer (second microcomputer) for controlling optical drive, and a microcomputer for controlling the main body. The exchange of various information signals with the computer (first microcomputer) 201 is serial communication. The optical scanning start signal sent from the first microcomputer 201 is directly supplied to the interrupt terminal of the second microcomputer 251.

The second microcomputer 251 generates various command signals in synchronization with a clock having a predetermined frequency (12 MHz) obtained from the reference clock generator 254.

The following control signal is output from the second microcomputer 251.

First, a control signal for turning on and off the drive circuit of the CCD 11 is supplied to the power supply control circuit (not shown). Second
Then, a predetermined control signal is supplied to the lighting control circuit 253 for the light source 85 for irradiating the original with necessary light.
Third, a driving circuit 252 for driving a stepping motor 90 for moving the carriage 84 and the V mirrors 89, 89 '.
Is also supplied with a control signal.

Data indicating the home position is input to the second microcomputer 251.

The first microcomputer 201 is mainly for controlling the printer unit 10C. FIG. 26 shows an example of an input system and an output system related to this.

The operation / display unit 202 receives various input data such as a magnification specification, a recording position specification, and a recording color command, and displays the contents thereof. As the display means, an element such as an LED is used.

The paper size detection circuit 203 is used for detecting the size of the cassette paper loaded in the tray, displaying the detected size, or automatically selecting the paper size according to the size of the document.

The cassette zero sheet detection sensor 220 detects whether the number of sheets in the cassette is zero. Manual feed zero sheet detection sensor
In step 222, the presence / absence of paper for manual feed in the manual feed mode is similarly detected.

The toner density detection sensor 221 detects the density of the toner on the drum 110 or after fixing.

Further, the developing device 123 is detected by the toner remaining amount detection sensor 223.
Is detected, and when the toner supply is necessary, the display element for toner supply provided on the operation unit is controlled to be turned on.

The temporary stop sensor 224 is for detecting whether or not the paper is correctly fed from the cassette to the second paper feed roller (not shown) during use of the copying machine.

Contrary to the above, the paper discharge sensor 225 is for detecting whether or not the sheet after fixing is correctly discharged outside.

The manual feed sensor 226 is used to detect whether the manual feed tray is set. If it is set, it will automatically enter manual feed mode.

The sensor output obtained from each sensor as described above is the first
The necessary data is displayed on the operation / display unit 202, and the driving state of the copying machine is controlled as desired.

In the case of copying, a developing motor 227 is provided, all of which are controlled by a command signal from the first microcomputer 201. Similarly, the drive state of the main motor (drum motor) 204 is controlled by a drive circuit 205 having a PLL configuration. The drive state of this drive circuit 205 is also controlled by a control signal from the first microcomputer 201. Will be.

At the time of development, it is necessary to apply a predetermined high voltage to a developing device during development.

Therefore, high-voltage power supply 228 for charging, high-voltage power supply 2 for development
29, a high-voltage power supply 230 for transfer and separation, and a high-voltage power supply 231 for toner reception are provided, and a predetermined high-voltage is applied to them when necessary.

Reference numeral 233 denotes a cleaning roller driving unit, 234 denotes a driving unit for the first paper feeding roller, 235 denotes a driving unit for the second paper feeding roller, and 232 denotes a motor for releasing the cleaning pressure. Further, reference numeral 236 denotes a drive unit for the separation claw.

The second paper feed roller is used to convey the paper conveyed from the first paper feed roller to an electrostatic latent image formed on the drum 110.

The fixing heater 208 is controlled by a fixing heater ON / OFF circuit 207 in accordance with a control signal of the first microcomputer 201.

The fixing temperature is read by the thermistor 209, and the first microcomputer 20 is set to always maintain the proper temperature.
Controlled by 1.

 206 is a clock circuit (about 12 MHz).

A non-volatile memory 210 provided in association with the first microcomputer 201 is used to store data to be stored even when the power is turned off. For example, it is data of a total counter or an initial set value.

Thus, the first and second microcomputers 20
In 1,251, various controls necessary for image formation are executed according to a predetermined sequence.

FIG. 27 is a timing chart schematically showing recording of an image. Detailed description is omitted.

Next, the operation / display unit 202 of the present apparatus will be described with reference to FIG.

(A) is a copy switch, and when this switch is pressed, a copying operation is performed in the above-described sequence. There is also an LED below this switch. When the red LED is lit, it indicates warm-up, and the green LED turns on to enter the ready state.

(B) is a display unit for displaying the number of copies, a self-determination mode, or showing an abnormal state and its part. 7-segment LE
It is composed of D and its contents are displayed by numbers.

(C) is a key group for setting the number of copies and the like, instructing the self-diagnosis mode operation, interrupting the copying operation, clearing the number of copies, and the like.

For example, it is possible to enter a self-diagnosis mode by turning on the power switch by pressing the numeric keys 4 and 7, and by inputting a specific number at this time, for example, the motor of the developing unit is independently rotated. It is possible. From this mode, it is possible to return to the normal mode by inputting a specific number or turning on the power without pressing a key after the power is turned off.

In the normal mode, a normal copying operation can be performed. However, by combining the numeric keys and the P button, operations such as data printout and test pattern printout can be performed.

For example, a test pattern in a memory can be printed out. If the stop / clear key is pressed during the copy operation, the operation proceeds to the post-rotation process operation, and after this operation is completed, returns to the initial state. The same applies to the copying of a large number of sheets.

The key of (d) is a key for selecting character image processing and photographic image processing.

(H) is a key for instructing that the area is to be detected entirely or partially, and when this key is pressed, a marker area on the document is detected. The designation of the inside / outside of the marker area and the entire screen is changed every time the key (h) is pressed.

On the other hand, the key group (R) is a key for designating a process.

The key (e) is a key for selecting the EE mode or the manual mode. In EE mode, it is enabled when a character is selected. With the key (e) ′, a gamma correction curve is selected. In this case, seven different curves are prepared.

The key of (G) is a key for selecting the paper feed size, and B5
You can select from R to A3 size and postcard size.

The key (i) is a key for selecting whether to use as a printer or as a copy.

The (nu) key is a key for distinguishing online / offline in the print mode.

The key of (ヲ) is a key for selecting a portrait and a landscape in the print mode.

Now, various kinds of image processing described below can be performed using the functions described above.

Inverting processing mode When performing the entire screen, specify "full screen" and then press the "invert" key to copy (see FIG. 29).

In the case of performing a partial operation, after specifying the inside / outside of the marker, press the “reverse” key to copy (see FIG. 30).

Filling processing mode For example, the user presses the marker “in” key to copy (see FIG. 31).

Shading Processing Mode After specifying "Full Screen", press the "Shading" key and then copy (see Fig. 32).

After specifying the “inside” side with the marker, press the key and press the “shaded” key before copying (see FIG. 33).

Hollow processing mode After commanding "entire", press the "contour (hollow)" key, and then press the copy key (see Fig. 34).

After the designation in the marker, press the "Nuke" key, and then specify the shading and press the copy key (see Fig. 35).

Reverse processing mode After specifying the marker, press the reverse key to copy.
Figure).

Zooming processing (W) is a key for setting the fixed and vertical / horizontal zoom magnification. Pressing this key turns on / off the LED and sets the processing of the specified magnification. Copies are made according to the magnification (FIGS. 37 and 38).

To set the magnification to an arbitrary magnification and perform zoom magnification, press the (W) key, select "Vertical magnification / Horizontal magnification", and select the magnification with the (F) key.

Set the fixed magnification with (W) and press the (F) key.
By selecting a magnification from B5 size to B4 size, a fixed magnification setting with the same vertical and horizontal magnifications is possible.

On the other hand, in this state, press (W) to select the vertical,
When the magnification is selected with the key, the horizontal magnification is the initial magnification and the vertical magnification is the magnification set thereafter, and vertical / horizontal independent magnification can be realized.

 Conversely, pressing the horizontal key instead of the vertical key is the same.

A different method may be adopted in which the "vertical" key is first pressed to set the vertical magnification, and then the "horizontal" key is pressed to set the magnification.

Extraction processing mode After designation within the marker, copy after pressing the "Extract" key (see FIGS. 39 and 40).

Erasure processing mode The function is the reverse of the extraction processing mode (see FIG. 41).

By using the key switch group of (c), it is possible to instruct various operations for confirming the operation. For example, (I) 6XP: Scanner check 60P + copy; light source (halogen lamp) is turned on, scanner optical system is stopped, 1+ copy in this state; halogen remains on, only optical system at slower speed than normal speed in the sub-scanning direction Move. However, when the copy switch is turned off, the optical system stops at that position while halogen is on. 2 + copy; 1 + copy, the optical system moves in the opposite direction 3 + copy; regular scan continues with halogen on 61P + copy; When halogen is off and the scanner is in the optical system stopped state, pressing 1-6 + copy in this state will perform the same operation as above.

This operation is canceled by pressing the stop / clear key. At the time of each operation, it is possible to check the signal level of the image data output from each circuit.

(II) 7XP: Printer section check 70P + copy; only the polygon motor rotates and the laser turns on. Index signal can be checked. In this state, 1 + copy; print data controller output 2 + copy; test pattern data output 3 + copy; patch data output possible 71P + copy; recording unit related check mode, 1 + copy in this state Charger ON 2 + Copy; Developer motor ON, Developing bias ON 5 + Copy; Transfer pole ON 6 + Copy; Cleaning blade crimping 7 + Copy; Cleaning blade release 8 + Copy; Cleaning roller applied (voltage) 9 + Copy; Separation pole ON 10 + Copy; 1st paper feed motor on 11+ copy; 2nd paper feed motor on etc. are performed. In this case, the mode is canceled by pressing the stop / clear in the same manner as described above.

Not only in this example, it is possible to perform such a self-diagnosis check, by facilitating maintenance of service personnel in the market, and by allowing the user to perform a simple check before going to the maintenance. Quick response to breakdowns.

[Effects of the Invention] As described above, according to the present invention, when the detection of both edges of the image in the main scanning direction and the detection of both edges of the image in the sub scanning direction are performed, the images in the main scanning direction and the sub scanning direction are used. The same number is extracted for a predetermined pixel before and after the pixel specifying the edge.

With this configuration, the same number of pixels before and after a specific pixel of the image in the main scanning direction and the sub-scanning direction make it possible to capture both edges of the image in a limited manner. Can be extracted as a contour.

According to this, it is possible to reliably extract the outline of the image including the end points. For this reason, the contour of the image can be extracted regardless of whether the background portion has an acute angle or not, and the white spot does not occur as in the related art.

Therefore, the contour extracting apparatus according to the present invention is extremely suitable for application to an image forming apparatus such as an electrophotographic copying machine as described above.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of a hollowing-out processing circuit which is a contour extracting apparatus according to the present invention, FIGS. 2 and 3 are waveform diagrams for explaining the operation thereof, and FIG. 4 is applicable to the present invention. FIG. 5 is a system diagram of an image processing section of the image forming apparatus, FIG. 6 is a schematic diagram of an electrophotographic copying apparatus applicable to the present invention, and FIG. 7 is a deflection diagram. FIG. 8 is an explanatory diagram of an image forming process, FIG. 9 is a system diagram of a shading correction circuit, FIG. 10 is a system diagram of a filtering process, and FIGS. 11 and 12 are diagrams of region extraction. FIG. 13, FIG. 13 is a waveform diagram for explaining region extraction, FIG. 14 is a system diagram of signal processing means, FIG. 15 is an explanatory diagram of a tint block pattern, FIG. FIG. 17 is an operation waveform diagram, FIG. 18 is a curve diagram showing overall characteristics of the image forming apparatus, and FIG. 19 is a density diagram. FIG. 20 is a system diagram of a PWM modulation circuit, FIG. 21 is a waveform diagram for explaining its operation, FIG. 22 is a curve diagram of recording characteristics with respect to laser power, and FIG. 23 is a charging voltage and recording characteristics. FIG. 24 is a system diagram of the printer unit, FIG. 25 is a configuration diagram of the second control unit, FIG. 26 is a configuration diagram of the first control unit, and FIG. FIG. 28 is a waveform diagram for explanation, FIG. 28 is a diagram showing a key arrangement state of the operation / display unit, FIGS. 29 to 41 are explanatory diagrams of key operation processing, respectively, FIG. The figure is a system diagram of a conventional hollowing-out processing circuit, and FIGS. 44 and 45 are explanatory diagrams of the operation thereof. 10 image forming apparatus 10A scanner section 10B image processing section 10C printer section 11 CCD 24 filtering processing circuit 30 scaling processing circuit 40 inversion processing circuit 45 gamma correction Circuit 50: Automatic density adjustment circuit 60: Mirror image processing circuit 65: Print data controller 110: Image forming body 300: Signal processing means 400: Background pattern processing circuit 500: Hollow processing circuit 600: PWM Modulation circuit

Claims (1)

(57) [Claims] An apparatus for extracting contour information of an image from image data in units of pixels of an image obtained by scanning an image acquisition system in a main scanning direction and a sub-scanning direction, wherein the main scanning is performed. First edge detecting means for detecting edges at both ends of the image scanned in the sub-scanning direction, and detecting edges at both ends of the image scanned in the sub-scanning direction A second edge detecting means for calculating the output of the first and second edge detecting means to extract contour information of the image, and detecting both edges of the image in the main scanning direction; When detecting both edges of the image in the sub-scanning direction, an equal number is extracted for a predetermined pixel before and after a pixel specifying an edge of the image in the main scanning direction and the sub-scanning direction. Contour extraction apparatus according to.