JP2918929B2 - Color image processing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image processing apparatus suitable for application to a full-color copying apparatus and the like, and more particularly, to the quality of a recorded image due to uneven density of a marker written on a document. Does not deteriorate.

[Background of the Invention] Color images such as character images and photographic images are represented by red R, green G, and blue B.
Is read optically, converted into a recording color such as yellow Y, magenta M, cyan C, black K, and recorded on recording paper using an output device such as an electrophotographic color copier based on the color. There is a color image processing apparatus that performs the processing.

Some of such color image processing apparatuses have a marker color conversion processing function of converting a portion surrounded by a marker among black characters of a black-and-white document into the same color as the marker.

[Problems to be Solved by the Invention] In the marker color conversion circuit used in such a color image processing apparatus, the area of the marker MC written on the original and the color thereof are set for each scan line as shown in FIG. And the area and marker color are determined for each scan line. In the figure, "•" points indicate sampling points for determining the marker color.

On the other hand, when this marker color conversion processing function is used, the recording density of the image contained in the area surrounded by the marker MC is
In some cases, depending on the density of the marker, if the density of the marker MC is different, the density unevenness appears as the unevenness of the recording density. Therefore, the recording quality may deteriorate.

In addition, for example, as shown in FIG.
For example, when the upper half is marked with a red marker and the lower half is marked with a blue marker, the image existing in the area surrounded by the marker has the same color as the marker color. , The upper half is recorded in red and the lower half is recorded in blue.

In this case, it is easier to see if the color is recorded in the same color as the first marker MC.

In view of the above, the present invention solves such a problem, and prevents the quality of a recorded image from deteriorating due to uneven density of a marker and preventing an image from being recorded in a plurality of colors.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an apparatus for performing a color image processing on an original image including black characters surrounded by markers of an arbitrary color. Image reading means for reading as a color separation image and inputting data of the color separation image read by the image reading means, and determining whether each pixel of the color separation image belongs to white / achromatic / chromatic color Color reproduction means for outputting a color code to be displayed and density data for reproducing the color separation image into a recording color; and marker color conversion means for converting black characters in the area surrounded by the marker into the color of the marker. An area for detecting a marker portion of the document image based on a color code from the color reproducing means, and for detecting a black character in an area surrounded by the marker portion. An output section, a marker color sampling section that scans the marker section detected by the area detection section and sets a sampling point on a scanning line of the mark section, and a marker on the scanning line set by the marker color sampling section. The density data of the color at the sampling point of
A marker color density determination unit that determines the color data to be density data relating to a converted color of a black character in an area surrounded by the marker and the entire color of the mark part.

[Operation] According to the present invention, the area detection unit detects the marker portion of the original image based on the color code,
When a black character in the area surrounded by the marker is detected, the marker is scanned by the marker color sampling unit, and a sampling point is set on a scanning line of the mark. Then, the marker color density determination unit converts the density data of the color at the specific sampling point on the scanning line into density data relating to the entire color of the mark part and the converted color of the black character in the area surrounded by the marker. Is determined as follows.

Therefore, even when the marker is accompanied by density unevenness or multiple colors, the density data for making the entire mark portion the same color and the density data for the converted color of the black character in the area surrounded by the marker Can be unified (identified), so that the color of the black characters and symbols surrounded by the marker and the marker color can be image-recorded in the same color. This allows
No unevenness of density and no multicolor in the marker image.
It is possible to improve the quality of a color character image or the like that has been color-converted in a region surrounded by the mark image.

Next, an example of a color image processing apparatus according to the present invention will be described in detail with reference to the drawings.

First, the outline of the color image processing apparatus of the present invention will be described with reference to the block diagram of FIG.

In this figure, 1 is an R-CCD for converting a red original image to an image signal, 2 is a G-CCD for converting a green original image to an image signal, and 3 is a B-CCD for converting a blue original image to an image signal. C
It is a CD.

Therefore, the image information (optical image) of the document is separated into R, G, and B colors by a dichroic mirror (not shown) and formed on the corresponding CCDs 1, 2, and 3, respectively.

Reference numeral 4 denotes an A / D converter for converting a red image signal read by the R-CCD 1 into 8-bit digital data, and 5 denotes a G-CCD.
An A / D converter for converting the green image signal read in 2 into 8-bit digital data, and an A / D converter 6 for converting the blue image signal read in B-CCD3 into 8-bit digital data. It is a vessel.

When this A / D conversion processing is performed, shading correction is also performed based on the image data of the reference white plate.

Reference numeral 7 denotes a density converter for converting red 8-bit digital data to 6-bit digital data, 8 denotes a density converter for converting green 8-bit digital data to 6-bit digital data, and 9 denotes a blue 8-bit digital data. It is a density converter for converting to bit digital data.

Reference numeral 10 denotes a color code (a 2-bit code indicating whether each pixel is white / black / chromatic, for example, white: 00, black: 11,
Chromatic color: 10) processing and color reproduction (R, G, B → yellow Y, magenta)
M, cyan C, black K).

The color reproduction processing circuit 10 outputs a 2-bit color code and a 6-bit density signal for each of Y, M, C, and K.

Reference numeral 29 denotes a color ghost correction unit for performing color ghost correction. This is because unnecessary color ghosts (color ghosts) occur around black characters.

The color ghost correction detects whether a color ghost is present in a 1 × 7 window and converts the color code of the pixel in which the color ghost is detected into a color code of a correct color. This color ghost correction is performed in the main scanning direction and the sub-scanning direction.

Note that the technology of the color ghost correction unit 29 can use the technology disclosed in Japanese Patent Application Laid-Open No. 1-195775 or the like.

A marker color conversion circuit 30 detects a marker area of the document and converts the area into a marker color, and outputs a density signal D and a marker area signal Q of the marker color.

Reference numeral 80 denotes an image processing unit that performs various image processing such as filtering, scaling, shading, and the like on the density signal. Reference numeral 84 denotes a printer unit for forming a color image by sequentially superimposing toner images of respective colors of Y, M, C, and K on a photosensitive drum (OPC).

 Subsequently, each part will be described in detail.

First, the overall configuration and operation of a copying machine to which the color image processing apparatus according to the present invention is applied will be described with reference to FIG.

Here, the description will be made on the assumption that the original of the copying machine uses a color dry developing system. In this example, two-component non-contact development and reversal development are employed. That is, the transfer drum used in the conventional color image formation is not used, and the superposition is performed on the electrophotographic photosensitive drum on which the image is formed.

In the following example, in order to reduce the size of the apparatus, a four-color image of yellow Y, magenta M, cyan C and black K is developed on an OP photoconductor (drum) for image formation by rotating the drum four times. A description will be given of a case in which transfer is performed once after development to transfer the image to recording paper such as plain paper.

The document reading unit A is driven by turning on a copy button (not shown) of the operation unit of the transfer machine. And the platen
The 128 originals 101 are optically scanned by the optical system.

This optical system includes a carriage 132 provided with a light source 129 such as a halogen lamp and a reflection mirror 131, and a movable mirror unit 134 provided with V mirrors 133 and 133 '.

The carriage 132 and the movable mirror unit 134 are moved by a stepping motor (not shown).
6 at a predetermined speed and direction.

Optical information (image information) obtained by irradiating the original 101 with the light source 129 is guided to the optical information conversion unit 137 via the reflection mirror 131 and the V mirrors 133 and 133 '.

Standard white plate 138 on the back side of the left end of platen glass 128
Is provided. This is for normalizing an image signal to a white signal by optically scanning the standard white plate 138.

The optical information conversion unit 137 has a lens 139 and a prism 14.
0, the two dichroic mirrors 102, 103 and R-CCD1 for capturing a red color separation image, G-CCD2 for capturing a green color separation image, and B-CCD3 for capturing a blue color separation image Be composed.

The optical signal obtained by the optical system is condensed by the lens 139, and is color-separated into blue optical information and yellow optical information by the dichroic mirror 102 provided in the prism 140 described above. In addition, dichroic mirror 103
Thus, the yellow optical information is color-separated into red optical information and green optical information. In this manner, the color optical image is decomposed by the prism 140 into three-color optical information of red R, green G, and blue B.

Each color separation image is formed on the light receiving surface of each CCD, so that an image signal converted into an electric signal is obtained.
After the image signal is subjected to the above-described signal processing in the signal processing system, the recording image signal of each color is output to the writing unit B.

The writing section B (printer unit 84) has a deflector 141. As the deflector 141, a deflector including an optical deflector using quartz 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 color signal is deflected and scanned by the deflector 141.

When deflection scanning is started, beam scanning is detected by a laser beam index sensor (not shown),
Beam modulation by the first color signal (for example, a yellow signal) is started. The modulated beam is charged uniformly by the charger 154 to the image forming body (photosensitive drum)
It is made to scan over 142.

Here, the main scanning by the laser beam and the image forming body 142 are performed.
Due to the sub-scanning due to the rotation of
An electrostatic latent image corresponding to the color signal is formed.

This electrostatic latent image is developed by a developing device 14 containing yellow toner.
3 to form a yellow toner image.
A predetermined developing bias voltage from a high-voltage power supply is applied to this developing device.

To supply toner to the developing unit, use CP for system control.
By controlling the toner replenishing means (not shown) based on a command signal from U (not shown), toner is replenished when necessary.

The above yellow toner image is the cleaning blade 147a
Is rotated in a state where the pressure contact is released, and an electrostatic latent image is formed based on a second color signal (for example, a magenta signal) in the same manner as in the case of the first color signal. Then, by using the developing device 144 that stores the magenta toner, the developing device 144 is developed to form a magenta toner image.

It goes without saying that a predetermined developing bias voltage is applied to the developing device 144 from a high-voltage power supply.

Similarly, an electrostatic latent image is formed based on the third color signal (cyan signal), and a developing device 145 containing cyan toner is formed.
As a result, a cyan toner image is formed. Further, an electrostatic latent image is formed based on the fourth color signal (black signal), and is developed by the developing device 146 filled with black toner in the same manner as the previous time.

Therefore, a multicolor toner image is formed on the image forming body 142 in an overlapping manner.

Here, the formation of a multicolor toner image of four colors has been described, but it goes without saying that a two-color or single-color toner image can be formed.

As described above, in the state where the AC and DC bias voltages are applied from the high-voltage power supply,
An example of so-called non-contact two-component jumping development in which each toner is caused to fly toward the image forming body 142 for development has been described.

The toner is supplied to the developing units 143, 144, 145, and 146 in the same manner as described above, and a predetermined amount of toner is supplied based on a command signal from the CPU.

On the other hand, the recording paper P fed from the paper feeding device 148 via the feed roll 149 and the timing roll 150 is the image forming body 1
The image forming body is synchronized with the rotation of 42.
Conveyed over 142 surfaces. Then, the multicolor toner image is transferred onto the recording paper P by the transfer pole 151 to which the high voltage is applied from the high voltage power supply, and is separated by the separation pole 152.

The separated recording paper P is conveyed to the fixing device 153, where a fixing process is performed to obtain a color image.

The image forming body 142 after the transfer is cleaned by the cleaning device 147, and prepares for the next image forming process. In the cleaning device 147, the cleaning blade 147a
A predetermined DC voltage is applied to the metal roll 147b in order to facilitate the recovery of the cleaned toner. The metal roll 147b is arranged on the surface of the image forming body 142 in a non-contact state. After the cleaning is completed, the cleaning blade 147a is released from the pressure contact.At the time of the release, an auxiliary roller 147c is further provided to release the unnecessary toner remaining.
This auxiliary roller 147c is rotated in the direction opposite to the image forming body 142,
By pressing, unnecessary toner is sufficiently cleaned and removed.

In FIG. 1, the color reproduction processing circuit 10 generates a 2-bit color code and Y, M, C, K density signals.

That is, a 2-bit color code (for example, white: 00, 00) indicating which pixel area a white / black / chromatic color area belongs to based on the level of each data of R, G, B
Black: 11, chromatic: 10; see FIG. 13). The process of generating the color code will be described below.

1. Generation of white code First, R, G, B are converted to the XYZ coordinate system by the following formula.

Then, the XYZ coordinate system is converted into the L ^* a ^* b ^* uniform color space by the following equation.

L ^* = 116 (Y / Yo) ^1/3 −16 ・ ・ ・ (2) a ^* = 500 {[(X / Xo) ¹ /3-(Y / Yo) ^1/3 ] ・ ・ ・ (3) b ^* = 200 {[(Y / Yo) ¹ /3-(Z / Zo) ^1/3 ] (4) Here, Yo = 100 Xo = 98.07 Zo = 118.23.

In the uniform color space L ^* a ^* b ^* thus obtained, L ^* ≧
Let 90 be a white area.

2. Generation of achromatic (black) code First, Q is obtained from the R, G, and B signals by the following equation.

Thus, the Q parameter is obtained, and Q ≦ 15 is set as a black area.

3. Generation of chromatic color code A chromatic color code is set by setting a region other than the white region and the black region as a chromatic color region.

Further, the color reproduction processing circuit 10 performs R, G, B → Y, M, C, and K by using, for example, an LUT (look-up table constituted by a ROM), and stores Y, M, C, and K 6 bits each. Concentration data is being created. At this time, since the spectral sensitivity characteristic of the scanner and the spectral reflectance of the toner are different as shown in FIG. 3, the density levels of R, G, and B obtained based on the scanner level are determined by the linear masking method. It is converted to the density level of C, M, Y toner.

 Here, the linear masking is represented by the following equation.

When this linear masking method is applied, FIG.
As is clear from the L ^* a ^* b ^* color matching coordinate system, R, G, B (original color) and Y, M, C after recording (copy) almost completely match.

 FIG. 5 shows a specific example of the color reproduction processing circuit 10 described above.

The R, G, B signals (luminance levels) are converted to linear masking means 20.
Then, the above-described density conversion processing is performed, and the data is converted into C, M, Y, and K. The reason why K is provided independently is to use K when copying a black and white original.

The converted C, M, Y, K are then subjected to under color removal by an under color removal means (UCR) 12.

FIG. 6 is an explanation of this UCR. In this example, 100% UCR in which C, M, and Y corresponding to the minimum density are removed and replaced with black K based on the minimum density of cyan C is illustrated. doing.

After removal of the undercolor, the toner adhesion amount conversion means 14 converts the density level into a toner adhesion amount M / A, and then the toner adhesion amount correction means 16 corrects the toner adhesion amount.

That is, when, for example, Y and M are overwritten with the writing pulse width Wa in the printer unit 84 as shown in FIG. 7, the toner adhesion amounts of Y and M should be originally the same (A in FIG. 7). However, in actuality, as shown in FIG. B, the toner adhesion amount of M is about 78% of that of a single color.

Therefore, as shown in FIG. 3C, by making the write pulse width of M wider than Y by Wb, the amount of M attached is made equal to that of the single color.

This makes it possible to correct the variation in the amount of toner attached to the photoconductor drum (OPC).

Any of C, M, Y, and K with the corrected toner adhesion amount is selected by the selector 18 and output. This is because, as described above, in the printer unit 84, the developing process is performed by superimposing while scanning one color at a time. Therefore, it is necessary to output C, M, Y, and K in synchronization with the scan color. Because there is. Therefore, the selector 18 is supplied with a 2-bit scan code.

The marker color conversion is a process of converting a portion surrounded by a marker among black characters of a document into the same color as the marker.

FIG. 8 is an explanatory diagram showing a state of the marker color conversion. A of the drawing shows an original before the marker color conversion, and FIG. B shows an output result recorded by the marker color conversion. As shown in this figure, the portion of the black character surrounded by the color marker is formed in the same color as the color of the marker. The color of the marker MC to be used is not particularly limited.

FIG. 9 is a system diagram of a marker color conversion circuit 30 which is a main part of the present invention.

In the figure, reference numeral 40 denotes an area detection unit, which detects a color marker of a document image based on the color code corrected by the color ghost correction unit 29, and detects an area surrounded by the marker MC and black characters in the area. Is extracted to generate a marker area signal Q. Reference numeral 50 denotes a marker color sampling unit which scans the marker portion detected by the above-described region detection unit and sets a sampling point on a scanning line of the mark portion. In this example, when the marker area signal Q is obtained, the marker color sampling unit 50
The density data of the marker color (any of C, M, Y, K) is sampled and a sampling signal (density data)
H is obtained.

Reference numeral 60 denotes a marker color density determination unit which converts the density data of the color at a specific sampling point on the scanning line set by the marker color sampling unit 50 into the entire color of the mark part and the area surrounded by the marker. Is determined to be the density data relating to the converted color of the black character. That is, it is determined whether to use the sampled sampling signal H as it is as the density data of the marker MC. Therefore, it is supplied with the marker area signal Q, the sampling signal H, and the monitoring signal E described below.

A marker sampling monitoring unit 52 monitors the validity / invalidity of the sampling of the marker MC based on the color code, and obtains a monitoring signal E.

Reference numeral 72 denotes a marker removal circuit for preventing the marker MC from being recorded. For this, a scan code is supplied in addition to the color code, the density data D, and the marker area signal Q.

The marker removal circuit 72 allows the input black K data to pass as it is when black K is being recorded by the printer unit 84, and the black in the marker area when Y, M, C, K is being recorded. Pass only data.

 Therefore, the truth table is as shown in FIG.

Numeral 74 denotes a black color conversion circuit, which performs multiplication only in the marker area, and passes black data in other areas.

Therefore, this includes a marker color density signal V,
In addition to the density data D, the color code, and the marker area signal Q, a 2-bit scan code is supplied, and the density data D of the black image surrounded by the marker MC is converted into a marker color and output.

That is, as shown in FIG. 11, the output density data is output by multiplying the input density data D by the coefficient V / Do (Do is an arbitrary constant).

Subsequently, each part of the marker color conversion circuit 30 will be described in detail.

FIG. 12 shows an example of the area detection unit 40, which is composed of a marker outage correction circuit 40A and a marker area processing circuit 40B.

The marker break correction circuit 40A corrects blurring, breakage, and the like of the marker in the main scanning direction and the sub-scanning direction.
First, the color code is converted into a marker signal MS in the marker signal conversion unit 41.

Since the marker signal MS is obtained when the color code is chromatic, the relationship between the color code and the marker signal MS is as shown in FIG.

The marker signal MS is supplied to the main scanning direction marker break correction unit 42.

FIG. 14 is a specific example of the marker break correction unit 42,
A delay element 421 for one pixel in a plurality of stages, in this example, seven stages
427 are connected in cascade, and the respective outputs are supplied to the flag processing unit 428. When all the inputs become “1”, the marker continuation flag becomes “1”, which is latched by the latch circuit 429.

The marker continuation flag is supplied to the flag processing unit 428 and the output marker signal calculation unit 430, and the output Mi of the first-stage delay element 421 is input to the marker signal calculation unit 430. Marker signal calculator 4
Reference numeral 30 denotes an OR circuit, which is logically designed so that the output marker signal MS always becomes "1" when the marker continuous flag or the marker signal Mi is "1".

In this way, it is possible to correct at least seven pixels in the marker in the main scanning direction.

After correcting the marker break in the main scanning direction, the marker break correction unit 44 at the next stage corrects the marker break in the sub-scanning direction by the same processing as described above. In this example, at least seven lines of marker breaks are corrected.

The marker area processing circuit 40B generates a marker area signal Q corresponding to the area surrounded by the marker signal MS. Fifteenth
This will be described with reference to FIG. 16 and FIG.

In this figure, a marker signal obtained when scanning is performed as in s is as shown in FIG. 16Ms. It is also assumed that the area signal obtained during the immediately preceding scan s-1 (not shown in FIG. 15) is Qs- ₁ in FIG. Here, the logical product signal Qs ₋₁ × Ms of both is taken, and an edge detection pulse Rs from the rising edge to the falling edge of this Qs ₋₁ × Ms is created. Then, a logical sum signal Qs of the marker signal Ms and the edge detection pulse Rs is created. This signal Qs is used as the marker area signal Q of the current scanning line s.

Similarly, the marker signal obtained when scanning as shown in FIG. 15 t is as shown in FIG. 16 Mt. It is also assumed that the area signal obtained during the immediately preceding scan t-1 (not shown in FIG. 15) is Qt- ₁ in FIG. Here, the logical product signal Qt _-1 × Mt of both is taken, and an edge detection pulse from the rising edge to the falling edge of this Qt _-1 × Mt is taken.
Create Rt. Then, an OR signal Qt of the marker signal Mt and the edge detection pulse Rt is created. This signal Qt is used as the marker area signal Q of the current scanning line t.

As described above, the area of the marker is detected. In the next processing, it is necessary to sample the color data of the marker.

In this example, for the sake of stability of color data, the density levels of four pixels are sampled from four pixels from the edge of the marker (FIGS. 17A and 17B), and the average value is used in the marker signal MS. Sampling signals H (density data) of C, M, Y, and K are used (C in the figure).

The marker sampling monitor 52 of FIG.
This is a means for treating the sampling process in the marker color sampling unit 50 as valid when there is no achromatic color code in the MS.

Therefore, as shown in FIGS.
A monitoring signal E for validating the sampling process is output only when there is a color code indicating an achromatic color outside the region.

 Next, the marker color density determination unit 60 will be described.

As shown in FIG. 18, this is composed of a marker color density determining logic unit 62, a memory 64 for writing and reading within a cycle of one pixel, and a pair of latch circuits 66 and 68.

In the figure, in order to facilitate the description of the write and read operations of the memory 64, it is illustrated as if there are two memories 64.

U is the content of the 2-bit counter, V is the density data of the marker color, n is the scan line, j is the pixel number, and F is a flag indicating the determination of the density data of the marker color.

The marker color density determination logic unit 62 includes (1) a marker area signal Q (2) a sampling signal H (3) a monitoring signal E (4) a flag F (5) a counter output U read from the memory 64 (6) The current line read from the memory 64 and the density signal V 1 before the current line are supplied, and from this, (7) the counter output U of the current line written to the memory 64 (8) the current line written to the memory 64 Is output.

Now, a description will be given of the conditions under which the density of the marker MC is specified. In the following example, it is assumed that the data on the third line after entering the marker area is the data of the marker MC.

(I) When Q = 0 In this case, Uj (n) = 0 Vj (n) = 0 is written because no color conversion processing is required outside the marker area, and Fj = 0.

(II) Q = 1, Uj + 4 (n-1) <3, E = 1, Fj = 0 For example, when the first line of the marker MC is scanned, if the sampling of the fourth and subsequent pixels is valid, 9 Since E = 1 from the pixel, the counter output Uj + incremented by one, such as Uj (n) = Uj + 4 (n−1) +1 Vj (n) = H Fj = 0
4 (n-1) +1 is the counter output Uj (n) of the current line n
Since the density data is stored for the first time, the density data Vj (n) of the sampling signal H is stored in this case.

That is, as shown in FIG. 19, density data (average value) obtained at the ninth pixel is stored. However, since the density data of the third line is used, the density data of the marker MC has not been determined yet.

In FIG. 19, the circles indicate pixels on each line, and among them, the triangles indicate the ninth pixel on each line, and the inside of each line is used as density data. Indicates that

(III) Q = 1, Uj + 4 (n-1) <3, E = 0 or 1, Fj = 1 In the tenth pixel of the same n line, data of one pixel before is stored. That is, Uj (n) = Uj + 4 (n-1) +1 Vj (n) = Vj-1 (n) Fj = 1 Therefore, as shown in FIG. 19, the density data of the ninth pixel is stored as it is. This operation continues until the line n is outside the marker area. Therefore, the density data of the ninth pixel is sequentially propagated in the scan direction.

Until the number of scan lines becomes four, the density data (sampling signal H) of the ninth pixel of the same scan line is obtained based on the above conditions (II) and (III).
Is stored as the density data Vj (n) of the line.

(IV) Q = 1, Uj + 4 (n-1) = 3, E = 1 At the n + 3 line, that is, at the fourth line, the density data four pixels after the same pixel position of the previous line is the density data of the current line. Is stored as. Therefore, Uj (n) = Uj + 4 (n-1) (= 3) Vj (n) = Vj + 4 (n-1) Fj = 1 In the case of FIG.
The density data after the pixel is the density data of the ninth pixel of the n + 2 line.

Density data of Vj (n) = Vj + 4 (n-1) is stored in memory from the tenth pixel on the same n-th line in accordance with the conditional expression (IV).

The same operation will be performed after the (n + 4) th line.
Therefore, as shown in FIG. 20, the density data of the sampling point q sampled on the third line propagates as it is in the scanning line direction. Therefore, the density data of the third line is used as the density data of the marker MC.

In this way, the density of the marker MC becomes the density determined on the third line, and even if the color changes or the density decreases in the middle of the marker MC, the processing can be performed without being influenced by the color or the density.

(V) Q = 1, Uj + 4 (n-1) <3, E = 0, Fj = 0 If the sampling is not valid by 3 lines and the flag F is not determined (actually, Although such cases are rare), that is, when E = 0 and Fj = 0, the density data of the previous line is stored according to the following conditions.

Uj (n) = Uj + 4 (n-1) Vj (n) = Vj + 4 (n-1) Fj = 0 In the above description, the case where the present invention is applied to a color copying machine has been described. It is needless to say that the color image processing apparatus described above can be used in other apparatuses for processing various color images.

[Effect of the Invention] As described above, according to the present invention, the density data of the color at a specific sampling point of the marker portion of the document image is
A marker color density determination unit is provided for determining the entire color of the mark and the density data relating to the converted color of the black character in the area surrounded by the marker.

With this configuration, even when the marker has uneven density or multiple colors, the density data that makes the entire mark portion the same color and the density related to the converted color of the black character in the area surrounded by the marker Since data can be unified,
An image can be recorded in the same color with high reproducibility between the color of black characters and symbols surrounded by the marker and the marker color. Therefore, it is possible to improve the quality of a color character image or the like that has been color-converted in an area surrounded by the mark image, without causing density unevenness or multiple colors in the marker image.

[Brief description of the drawings]

FIG. 1 is a system diagram of a color image processing apparatus according to the present invention,
FIG. 2 is a configuration diagram showing the overall configuration of the copier, FIG. 3 is a characteristic diagram showing the spectral characteristics of the scanner and the spectral reflectance of the toner,
FIG. 4 is a diagram showing L ^* a ^* b ^* coordinates, FIG. 5 is a system diagram of a color reproduction processing circuit, FIGS. 6 and 7 are explanatory diagrams thereof, FIG. FIG. 9 is a block diagram showing a configuration of an embodiment of a marker color conversion circuit which is a main part of the present invention.
FIG. 11 and FIG. 11 are explanatory diagrams thereof, FIG. 12 is a system diagram of an area detecting unit, FIG. 13 is an explanatory diagram thereof, FIG. 14 is a system diagram of a main scanning direction marker break correction unit, FIG. FIG. 17 is an explanatory diagram of a marker area signal, FIG. 17 is an explanatory diagram of sampling, FIG. 18 is a system diagram of a marker color density determining unit, FIG. 19 and FIG. And No. 22 is a conventional explanatory diagram. 1 ... R-CCD 2 ... G-CCD 3 ... B-CCD 4,5,6 ... A / D converter 7,8,9 ... Density conversion unit 10 ... Color reproduction processing circuit 11 ... Color ghost correction unit 20: Linear masking circuit 30: Marker color conversion circuit 40: Area detection unit 50: Marker color sampling unit 52: Marker sampling monitoring unit 60: Marker color density determination unit 72: Marker removal Circuit 74: Black color conversion circuit 80: Image processing unit 82: PWM multi-value conversion unit 84: Printer unit

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tetsuya Niizuma 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (72) Inventor Koji Washio 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (56) References JP-A-63-292874 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 1/387 H04N 1/46 G06T 1/00

Claims (1)

(57) [Claims] 1. An apparatus for performing color image processing of a document image including black characters surrounded by markers of an arbitrary color, comprising: an image reading means for separating the image into three colors and reading it as a color separation image; Data of the read color separation image is input, a color code indicating whether each pixel of the color separation image belongs to white / achromatic color / chromatic color, and a color code for reproducing the color separation image into a recording color. Color reproduction means for outputting density data; and marker color conversion means for converting black characters in the area surrounded by the marker into the color of the marker. Detecting a marker portion of the document image based on the color code, and scanning a marker portion detected by the region detection portion for detecting a black character in a region surrounded by the marker portion; A marker color sampling unit that sets a sampling point on the scanning line of the mark unit; and a density data of a color of a specific sampling point on the scanning line set by the marker color sampling unit, the whole color of the mark unit and the A marker color density determining unit for determining density data relating to a converted color of a black character in a region surrounded by the marker.