JPH0225861A - Color picture processor - Google Patents

Abstract

PURPOSE:To eliminate the misdetection of a designated area due to the blur of a color marker and the unbalance of a CCD level by using the correcting means of the color information of an area designation also as a color ghost correcting means. CONSTITUTION:To a color ghost correcting means 300, a tape 304 to execute the blur correction of the color marker is prepared, and when a partial color converting mode is selected, the table is referred to. Consequently, since the table for correcting a color ghost is referred to in an ordinary recording mode, even when a color pattern is inputted, it is outputted in a condition as it is, and in the partial color converting mode, the blur correction processing of the color marker is executed simultaneously with the correction processing of the color ghost. Thus, the designated area can be detected without being influenced by the fluctuation of the output level of the CCD, etc., in addition to the blur of the color marker itself.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a color image processing device suitable for application to an image processing device such as a color copying machine for d-sheet recording, and has a partial color conversion function in Samurai. The present invention relates to a color image processing device in which a color ghost correction device rlh is added with a blurring correction function for a designated color.

[Background of the Invention] In a color copying machine using a color image processing device such as a laser beam, a color original is separated into a plurality of colors to obtain color image information, and a color image is created based on this color image information. I try to record it.

Such color copying machines are capable of various image processing such as scaling processing and partial color conversion processing.

Partial color conversion processing refers to image collection processing that allows image information inside or outside a designated area to be recorded in, for example, the color used for area designation.

Areas are usually specified using color markers. For example, when area a is specified using a blue marker as shown in FIG.
).

Images in other areas may be erased or recorded as normal black and white images.

In order to achieve such partial color conversion processing, it is necessary to detect each color for specifying an area, such as a color marker, and the area. For this purpose, as shown in FIG. 16, for example, markers No. 48 BP and RP are detected from color markers formed across each scanning line (n, n+1, etc.), and
Area signals QB'' and QR'' are formed from these signals.

These markers (No. 8 BP, RP and area No. 48 QB'.

QR'', the image of the specified area is extracted and recorded, and the recording process as shown in FIG. 15B is achieved.

By the way, in a color image processing apparatus equipped with such a partial color conversion processing function, it is necessary to accurately detect the color marker area as described above. However, the accuracy varies greatly depending on how the color marker is written.

In other words, if a color marker is correctly written on a document with high density, it is possible to detect the color marker with high accuracy.

However, if the color marker is faded in some places,
Since that part cannot be regarded as the area of the color marker itself, the detection area is cut off by the faded part.

Alternatively, CO, which is often used as an image reading means,
When the output levels of D are slightly different, the image becomes an image in which the color of the color marker and the black color of the image overlap in a part of the designated area.

To avoid such a situation, it is possible to provide area determination means for color markers or blur correction means. Utilizing these means makes it possible to accurately detect color markers, thereby eliminating erroneous detection of specified areas due to fading of color markers or imbalance in CCD levels.

[Problems to be Solved by the Invention] However, when using the area determination means, when there is a break in the color marker, information on the previous line is used, or even if there is a break in the color marker, several lines Alternatively, it is necessary to perform a judgment process such as ignoring several bits of area information, which has the disadvantage that the area judgment means becomes complicated.

When using a blur correction means, it is necessary to provide a dedicated means for blur correction, and it is also necessary to perform the same processing as the area determination means, which makes the configuration complicated.
This method has drawbacks such as increased cost.

Therefore, in the present invention, in a color image processing apparatus having a color ghost correction function in addition to a partial color conversion function, the color ghost correction means can be skillfully used to perform blurring processing of color markers. This paper proposes a color image processing device.

Means for Solving the Problem] In order to solve the above-mentioned problem, the present invention provides a color image processing device that performs image processing on color image information converted into an electrical signal. The apparatus is equipped with a color discrimination means for color image information, a color ghost correction means, and an image processing means for performing image processing on a specified area using color information different from the original color to be read. The present invention is characterized in that the color ghost correction means is also used as a correction means for area-designated color information.

[Function J] The color ghost correction means 300 is configured to include a correction means for area-specified color information.

In the normal recording mode, the color ghost correction means 300 only performs color ghost correction processing.

When the partial color conversion mode has been selected, the color ghost correction means 300 executes both the color ghost correction process and the blur correction process.

The reason why the color ghost correction means 300 is made to be able to perform the blurring correction processing function is because the blurring pattern becomes a pattern similar to the color ghost pattern. In that case, the appearance mode of cassoulet pattern is the 10th
Figure A and Figure 11 A or Figure 12 A, C and Figure 13
It will look like Figures A and C. This is because the color area of the color marker is not detected as the original color area due to the blurring.

On the other hand, since the appearance of the color ghost pattern is as shown in FIG. 81, the appearance of the two patterns is different, and the color ghost is not mistakenly judged to be a faded pattern.

[Example] Next, an example of a color image processing device according to the present invention will be described.
A case in which the present invention is applied to the color image processing apparatus of the color copying machine described above will be described in detail with reference to FIG. 1 and subsequent figures.

FIG. 1 shows an example of a color image processing device 1 according to the present invention, in which color image information (optical image) of a subject 2 such as a document is transmitted to a dichroic mirror 4 through an optical system 3.
It is separated into two color separation images.

In this example, the image is separated into a color-separated image of red R and a color-separated image of cyan Cy. Therefore, the dichroic mirror 4 used has a cutoff wavelength of about 540 to 600 nm.

The color separation images of red R and cyan Cy are supplied to an image reading means, for example, C0D6.7, and image signals of only the red component R and cyan component ay are output from each image reading means, for example.

The image signals R and CY are supplied to an A/D converter 10.11, where they are converted into digital signals having a predetermined number of bits, 6 bits in this example. Sieton correction is performed simultaneously with A/D conversion. Reference numeral 12.13 indicates a Schoetang correction circuit 4. The Schoetang-corrected digital image signal is extracted in the effective area extraction circuit 15 only for the signal corresponding to the maximum original size, and is supplied to the next stage color discrimination circuit 20. . When the maximum document width to be handled is 84 size, goo 618
As the signal, the size signal B4 generated by the timing signal generating means 170 of the system is used.

Here, if the digital image signals that have been subjected to Sietang correction are VR and VC, respectively, these image signals VR.

VC is supplied to the color discrimination circuit 20 and divided into a plurality of color signals.
Ill be ill.

In this example, a case is illustrated in which the signal is configured to be separated into three color signals: red, blue, and black.

That is, at t3, no matter what color the original is, each pixel is assigned to one of red, blue, and black. When this process is performed, each part of the document is recognized as a red, blue, or black color part.

In addition, if these red, blue, and black are other colors, roughly 4
This color discrimination processing also includes the determination of a color or more.

Each color-discriminated color signal is divided into color code data (2-pit chip) indicating its color information and density data (
6 and data).

Data for each of these color signals is stored, for example, in a color discrimination conversion table (map) of ROM configuration.

FIG. 2 shows an example of this color discrimination map.

The t+ can be configured such that a number of conversion tables for color discrimination are prepared, and these are selected depending on the type of document, for example. In this case, table selection processing is executed based on instructions from a microcomputer, which will be described later.

The color-discriminated image data is transferred to a color image processing step.

First, the color ghost is completely supplied to the next-stage color ghost correction means 300, and color ghosts in the main scanning direction (horizontal scanning direction) and the sub-scanning direction (drum rotation direction) are corrected.

This is because unnecessary color ghosts occur during color discrimination, especially around black characters.

An example of appearance of color ghosts is shown in FIG.

The figure shows the color ghost that appears after color discrimination is performed by capturing an image of the kanji character "sexuality" written in black.

As you can see from this example, as a color ghost,
As shown in FIGS. 4A to 4C, red and blue appear at the edge of the black line, black appears at the edge of the blue line, and black appears at the edge of the red line.

It is clear that color ghosts appear differently in other color combinations.

The color ghost correction means 300 is a circuit for correcting such color ghosts as much as possible.

Note that the color ghost processing is subject to b of the color code data.

In the present invention, the color ghost correction means 300 is configured to also function as a blurring correction means for a color marker for specifying an area, which will be described later.

Furthermore, only when the partial color conversion mode is selected, color marker blur correction processing is simultaneously executed. The details will be described later.

In addition to color ghost correction, image processing includes resolution correction, partial color conversion processing, scaling processing, multi-value processing, and the like.

First, the image data (color code data and density data) after color ghost correction is processed by the subsequent resolution corrector 'l1.
At 540, the density data is processed to determine the resolution (M
TF) is corrected.

Factors contributing to resolution deterioration include problems with the optical system, optical travel system, signal processing system, recording system, etc. However, it is the optical system and its travel system that do not directly affect the deterioration of resolution.

FIG. 5 shows MTF values (before correction) in the main scanning direction and the sub-scanning direction when the optical system is driven. This characteristic is 2~16d
These are the measured values when scanning a black and white pattern with a spatial frequency up to ots/am.

The MTF in this case was defined and used as MTF=(W-BK)/(w+BK)(%). Here, W is a white signal, BK is a black signal δ
This is the number.

The deterioration of M TF is more remarkable in the sub-scanning direction. In order to correct to the same extent, the amount of correction in the sub-scanning direction may be set to 2 to 4 times that in the main scanning direction.

In order to correct the main and sub-scanning directions to the same degree without deteriorating the reproducibility of fine line areas, use 383-pixel image data or a convolution filter as the resolution correction circuit. I can do it.

FIG. 6 shows the correction results when using the Compolis Cow 3-in filter.

The resolution-corrected density data and color code data are each supplied to a color data selector 50, and when the partial color conversion mode is selected, the image area is recorded in a specific color.

When performing image processing such as this partial color conversion mode, it is necessary to detect color markers written on the document and extract the area.

For this reason, a region extraction time "m60" is provided,
The area of the color marker on the document is detected, and area signals QR', QB'' (see FIG. 16) obtained from this are supplied to the data selector 50.

In addition to these signals, the data selector 50 is supplied with a scan two number 113 indicating which color is currently being copied and a partial color conversion signal CC.

Color = [A multi-color copying machine that can record multiple specific colors as an edge bar] develops one color per rotation of the photoreceptor drum until all colors are developed. In the case of a type in which a color image is recorded by subsequent transfer and separation processing, Scan2 No. 648 indicates how many colors are currently being developed.

Therefore, when a blue color marker is detected, in the blue copy sequence, if you shift so that the corresponding color data is output when the L5 area (g) is obtained, the 11th color marker images can be recorded in blue.

When the partial color conversion process is not performed, density data is output only for the edge of the color code data that matches the scan code 1 signal. That is, during the red copy sequence, while the red color code is being obtained, the corresponding density data is selectively output.

The image data output from the color data selector 50 (
The density data) is subjected to enlargement/reduction processing in a scaling circuit 70.

Enlargement/reduction processing is performed by interpolating the density data in the main scanning direction, and by controlling the scanning speed in the sub-scanning direction (rotation direction of the photosensitive drum).

If the scanning speed is increased, sampling data in the sub-scanning direction is thinned out, resulting in a reduction process; on the other hand, if the scanning speed is made slower, an enlargement process is performed.

In this example, the color code data is also subjected to enlarging/reducing processing at the same time, and is then supplied to the multivalue converting circuit 80.

Expansion/reduction processing is performed and t-density data is multivalued appearance #4
At 80, multivalue processing is performed. For example, by using four threshold values, 6-bit density data is quinarized.

Threshold data is set manually or automatically.

A histogram creation circuit 100 is provided to automatically determine threshold data.

Histogram Creation Circuit], OO creates a density pistogram as shown in FIG. 7 from certain captured image data, and calculates optimal threshold data for the image based on the created density histogram.

A density histogram may be created for each color, and multi-value processing may be performed for each color using threshold data calculated based on the density histogram.

The 3-bit multi-value data subjected to multi-value processing is supplied to the driver 40 via an interface circuit 130.

The driver 140 modulates the laser beam in accordance with the multilevel data. In this example, PWM modulation is performed.

The driver 140 may be built into the multi-level conversion circuit 80.

Output device 150 by a PWM modulated laser beam
A latent image is formed on the photoreceptor drum provided on the photoreceptor drum.

As the output device 150, an electrophotographic color copying machine using a laser beam is used. In this example, two-component non-contact jumping development and reversal development are employed.

That is, the transfer drum used in conventional color image formation is not used. On the OPC photoreceptor (drum) for image formation in order to make the device more compact.

The three-color image of blue, red, and black is developed with three rotations of the drum, and the yll
Post-post transfer is performed once to transfer onto recording paper such as plain paper.

The various image processing commands and image processing timings described above are all controlled by the CPU 60.

170 is a processing timing signal generation circuit for obtaining 3 types of processing timing, which includes
K, horizontal and vertical synchronization No. 13 HV, VV in the main scanning direction and sub-scanning direction obtained from the output device 150 side, as well as an index signal IDX indicating the start of scanning of the laser beam, etc., and these signals are Based on this, reading start timing No. 18 corresponding to C0D6°7 is formed.

180 is a timing signal generation circuit for obtaining scaling timing.

C1 In this invention, when the partial color conversion mode is selected, the above-mentioned color ghost correction means 300
However, the blur correction means is made to work as well. Therefore, the color ghost correction means 300 includes a blur correction pattern in addition to the color ghost correction pattern, and these are controlled based on instructions from the microcomputer 160.

Next, the contents will be explained in detail. First, color ghost correction will be explained.

In this example, color ghost correction is performed using a color pattern method. This is because the color ghost color that appears is determined for the original color, such as original black → red, helmet ghost original red, blue → black ghost. Therefore, according to this color pattern method, the color of the original image can be identified by examining the color appearance (pattern) of the pixel of interest and its surrounding pixels to determine the color of the pixel of interest.

As an example, FIG. 8 shows the relationship between the pixel of interest, the surrounding color pattern, and the color of the pixel of interest determined at that time.

In the first example, since both sides of the pixel of interest are white and black, the blue color of the pixel of interest is determined to be a color ghost appearing at the black edge. Red in the third example is also determined to be a color ghost of black. Therefore, in both the first and third examples, the pixel of interest is changed to black.

On the other hand, in the second and fourth examples, it is not determined that a color ghost has appeared, and the color of the first pixel is output as is.

This type of processing is difficult to implement with an arithmetic circuit, so in this example, it is implemented in ROM and LUT (lookup table).
It is used in the format. One-dimensional and two-dimensional methods are conceivable as color patterns, but if the number of colors is N and the number of pixels surrounding the pixel of interest is M, the size of the color pattern is NM. Therefore, if a two-dimensional pattern is used, the number of M will suddenly increase, making it impractical.

In other words, although a two-dimensional pattern cannot have a large number of peripheral pixels in each dimension (main scanning direction/sub scanning direction), the number of patterns increases. FIG. 9 shows the relationship between size and number of color patterns.

In this example, the size of IX7 in one dimension (that is, N
=4. M=7) color pattern is used, and color ghost removal is performed independently in the main scanning direction and the sub-scanning direction. At this time, since there is no difference in the appearance of color ghosts in the image between the main scanning direction and the sub-scanning direction, the same color pattern is used in the main scanning direction and the sub-scanning direction in this example.

As the color pattern size, we selected a size of 1 x 7, but if the degree of color ghost appearance is small, I
It is also possible to use smaller sized color patterns such as X5. Color ghosts of up to 1 pixel can be removed with a color pattern of size I×5, and color ghosts of up to 2 pixels can be removed with a color pattern of size ×7.

When using a color pattern of IX7 size, the color code is input as a ROM address.

For example, in the color pattern below, the color code pattern is white: white: blue: blue: black: black: black 11: 11:01:01:OO:
The address becomes 00:00, and a black code OO is stored at this address as shown in FIG. L U 'I' is executed using the above method.

In reality, a 1x7 pattern requires a 14-bit address line, and a bipolar ROM with 14-bit address input and 2-bit color coat output is sufficient, but such a large-capacity, high-speed ROM are not widely available on the market and are expensive. Further, the output of the ROM is generally 8 bits.

Therefore, in the embodiment, the output data of the ROM is selected based on the color code of the first pixel, and the LUT is performed using the color codes of the remaining six pixels. That is, the output data Do, Dl of the ROM are selected when the first pixel is black, and the output data D2. D3 is a helmet, D4. D5 is red, D6. D7 is selected when it is white.

Therefore, for example, in the color pattern shown in FIG. 8, the beginning is white, so in this case, among the output bits of the ROM,
Bit D6. Both D7 will be selected.

However, even if the first pixel is the same white, the selected output bit D6. The color code of the pixel of interest obtained at D7 is different as shown in FIG. This means that the ROM reference address is a combination of input pixels (a combination of color code data)
This is because it differs depending on the

When using a low-speed, large-capacity EFROM, it is also possible to transfer data to a plurality of SRAMs or the like before operation and perform color ghost correction using these SRAMs.

On the other hand, the appearance of the color pattern obtained upon detecting the color marker may be as shown in FIG. 10 and subsequent figures.

In other words, when a color marker is used, if there is no blurring, the pixels indicating the color marker are continuous over a plurality of pixels. However, when there is a blur, the pixels indicating the color marker are not continuous over a plurality of pixels, resulting in a state where a white pixel is sandwiched between the pixels.

When the blur is for one pixel, see Figure 10A (color ma...
11A (color marker is blue). If there is a blur of 2 pixels, please refer to Figure 12 A, C (using red color marker) and Figure 12.
This results in a faded pattern as shown in Figure 3 A and C (using blue color marker).

In the case of such a blurred pattern, all the white pixels sandwiched between the pixels indicating the color marker may be corrected to the pixels indicating the color marker (FIGS. 10 to 13B,
(See Figures 12B and D and Figures 13B and D).

In this way, since the color combinations that appear are different between the color pattern of a color ghost and the blurred pattern of a color marker, blurring correction of a color marker can be performed using the same method as the correction of a color ghost. .

Therefore, in the present invention, a table for correcting blurring of color markers is provided in the color ghost correction means 300, and this table is referred to when the partial color conversion mode is selected.

In this way, the table for color ghost correction is referenced in the normal recording mode, so the table shown in FIGS. 10 to 1
Even if a color pattern like the one shown in Figure 3 is input, it will be output as is. However, in the partial color conversion mode, color marker blurring correction processing is performed simultaneously with color ghost correction processing, and correction processing as shown in FIGS. 10 to 13 is performed.

Which conversion table is used depends on whether the partial color conversion mode is selected. Which table to use is selected by a signal supplied to the 13th bit of ROM 302.

FIG. 14 shows a specific example of a color ghost correction means 300 that accomplishes such processing. Color ghost processing is performed in the main scanning direction (horizontal scanning direction) and the sub-scanning direction (vertical scanning direction).

In this example, horizontal and vertical ghosts are removed using image data for 7 pixels in the horizontal direction and 7 lines in the vertical direction.

Color ghost processing applies only to color codes of image data.

Therefore, the color coat read from the color discrimination circuit 20 is first processed by the ghost correction circuit 300 in the output scanning direction.
A is supplied. Therefore, the color code data is sequentially supplied to a 7-bit shift register (SR) 301 and parallelized. This 7-pixel parallel color code data (2 x 7 bits) is used as a horizontal ghost removal RO.
M 302 t, - is supplied and ghost removal processing is performed for each pixel.

Here, the input bits of R0M302 are maximum 13 bits,
Since up to 8 output bits are used, the first 2 bits are used as selection bits as described above. Therefore, a selector 303 is provided after the R0M302, the first bit is supplied to this selector 303, and the remaining bits (12 bits) are supplied to the ROM302.
supplied to

As described above, the ROM 302 stores the color pattern data for color ghost correction and the color pattern data for frayed sleeve correction in the form of tables.

When the ghost processing is completed, the data is latched by the latch circuit 304.

On the other hand, the density data output from the color discrimination circuit #520 is transferred to the shift register (SR) 3 for timing adjustment.
05 (7-bit configuration) to the latch circuit 11306, and data transfer conditions are determined so that the density data is serially transferred following the color code data.

The serially processed color code data and density data are supplied to a line memory section 310 provided in the color ghost correction circuit 300B.

The line memory section 310 is provided to eliminate color ghosts in the vertical direction using seven lines of image data. It should be noted that whether the line memory has been used for a total of 8 lines indicates the means for real-time processing, and of course real-time processing is possible even for 7 lines.

The color code data and density data for eight lines are separated in the subsequent gate circuit group 320, respectively. In the gate circuit group 320, gate circuits 321-328 are provided corresponding to the line memories 311-318, respectively.

The output data of the 8 line memories synchronized in the line memory unit 310 is divided into color coat data and density data in the gate circuit group 320, and the separated color coat data is supplied to the selection circuit 330, so that a total of 8 Among the line memories of the book, color coat data of seven line memories necessary for color-ghost processing are selected. In this case, when line memory 311=317 is selected, the selected line memories are sequentially shifted such that line memories 312 to 318 are selected at the next processing timing.

The color code data for the 7 lines of memory that has been selected and synchronized is processed by the ghost removal R in the vertical 1α direction at the next stage.
It is fed to OM 340 to remove vertical color ghosts.

The vertical direction is also processed in the same way as the horizontal direction, and the input 13
In addition to the 8-bit ROM 340, a data selector 341 is provided, and the first 2 bits are used as a data selection signal.

As mentioned above, the ROM 340 has tables for color ghost correction data and blurring correction data, and which table to use is determined by the ROM.
The selection is made by the signal supplied to the 13th bit of 340. As this signal, a command signal outputted from the micro combi coater 160h1 in relation to the operation mode is used.

Thereafter, the latch circuit 342 latches it.

On the other hand, the density data separated by the gate circuit group 320 is directly supplied to the latch circuit 343, and is output after being timing-adjusted with the color code data.

[Effects of the Invention] As explained above, according to the present invention, data for blurring correction is stored in the color ghost correction means in addition to data for color ghost correction, and this data can be selectively used depending on the operation mode. It was designed to do so. In other words, the configuration is such that the color ghost correction means also serves as the force deviation correction means.

According to this configuration, when the partial color conversion mode is selected, in addition to the color ghost correction process, the blurring correction process is also performed, so that the area of the color marker can be accurately identified. As a result, it is possible to detect the specified area without the shadow #J being cut off due to not only blurring of the color marker itself but also fluctuations in the output level of the CCD.

Therefore, the present invention is extremely suitable for application to a color image processing apparatus such as the above-mentioned color copying machine.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of a color image processing device according to the present invention, FIG. 2 is a diagram of a color discrimination map, FIGS. 3 and 4 are explanations of color ghosts 14, and FIGS. 5 and 6. The figure is a characteristic diagram showing M'rF correction, Figure 7 is the cause of the density histogram, Figure 8 is a diagram explaining color ghost, and Figure 9 is a diagram showing the characteristics of M'rF correction.
The figure shows the relationship between color pattern and pattern size.
10 to 13 are diagrams showing the relationship between the blur pattern and its correction pattern, FIG. 14 is a system diagram of the color ghost correction means, FIG. 15 is an explanatory diagram of partial color conversion processing, and FIG.
FIG. 6 is a diagram showing the relationship between color markers, marker No. 3, and area No. 18. 1...Color image processing device 302. 20...Color discrimination circuit 40...Resolution correction circuit 50...Color data selector 60...Area extraction circuit 70...Scaling circuit 80...Multi-value conversion circuit 100...Histogram creation circuit l;30...Interface circuit 140...Natriver 150...Output device 160...CPU 300...Color ghost correction means 340...Correction 1 (OM

Claims (1)

[Claims] (1) In a color image processing device that performs image processing on color image information converted into an electrical signal, the color image information is read by a color discrimination means and a color ghost correction means. and an image processing means for performing image processing of a specified area using color information different from the original color to be used, and the color ghost correction means is also used as correction means for the color information of the area specification. color image processing device.