JPH0723210A - Color picture processor - Google Patents

Abstract

PURPOSE:To attain marker edit in a full color picture by extracting a marker color from the full color picture with high accuracy. CONSTITUTION:A fluorescent color identification section 3 discriminates a fluorescent color based on an RGB signal from a picture input section 1. Whether or not the fluorescent color is identified by comparing the input value of R, G with a predetermined threshold level because the reflectance of R or G takes a very high value in comparison with that of a white level. A picture processing section 5 executes the edit processing such as trimming or movement of an area surrounded by the fluorescent color or conversion of a predetermined area only into other color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for a digital copying machine, a color scanner or the like, which determines an area designated by a marker pen or the like in an image and applies predetermined image processing only to the determined area. Regarding

[0002]

2. Description of the Related Art In recent years, a method called marker editing has been adopted in digital copying machines. When editing, instead of designating coordinate points on the digitizer, a specific pen (this is called a marker pen) is used to enclose the area on the document, and the enclosed area is detected and trimmed. This is a method of performing processing such as masking and color processing. The editing method using such a marker pen is characterized in that it is easier to operate than the digitizer method and does not require a special device called a digitizer.

As a conventional technique for performing marker editing, for example, a document is read as a color image, white / achromatic color / chromatic color is determined based on color image data, and the chromatic color is regarded as a marker signal for processing. Method (JP-A-2-2493
54), read the original as a grayscale image,
A method of detecting the start point and the end point of a marker line by binarizing grayscale image data with two different thresholds (Japanese Patent Laid-Open No. 3-35369).
(See the official gazette).

[0004]

However, in the conventional marker editing, since the chromatic color and the halftone are discriminated as the markers, the target image is limited to the black and white gray image and the binary image, and the function thereof is the black and white image. However, when applied to a full-color image, there is a possibility of malfunction.

This will be described with reference to the color image of FIG. 8 as an example. FIG. 8 shows a color original consisting of a picture, black characters and a table. The ruled lines of the table are printed in red, and black characters are written in the table. Now, let us consider a case where the user encloses the title with a red marker pen and performs color processing in order to color the black characters in the title portion of the document.

In contrast to such an example, if red is determined as the marker color by the conventional method, the ruled lines of the table are also determined as the markers, so that black characters in the table that do not require color processing are colored. Problem arises. Similarly, there is a possibility that color processing will be performed even in the case of a picture including a red frame.

Further, in the example of FIG. 8, the case where red is used as the marker color has been described, but when all chromatic colors and halftones are regarded as marker colors as in the conventional method,
The possibility that the non-marker portion is erroneously determined as a marker is further increased. For this reason, it is extremely difficult to apply the conventional marker editing function to the color copying machine, and most image editing is performed by the digitizer method.

An object of the present invention is to provide an image processing apparatus capable of highly accurately extracting a marker color from a full color image and editing the marker in the full color image.

[0009]

In order to achieve the above object, according to the invention of claim 1, a color original is read,
In a color image processing apparatus having image input means for inputting color signals of a plurality of colors, a means for determining a fluorescent color from the input color signal or another color signal obtained by color-converting the color signal, and the determination result It is characterized in that it is provided with means for editing an image in an area designated by a fluorescent color accordingly.

According to a second aspect of the present invention, the determining means determines, for each pixel, a fluorescent color when one or more of the color signals of the color signals is equal to or more than a predetermined threshold value. There is.

According to a third aspect of the present invention, the determination means determines that, for each pixel, one or more color signals of the color signals are first.
Is more than or equal to the threshold value and the other color signal among the color signals is less than or equal to the second threshold value (where the first threshold value> the second threshold value), the color is determined to be a fluorescent color. .

According to a fourth aspect of the present invention, the determination means detects the background density of the document, and when one or more of the color signals of the pixel of interest is higher than the background color signal, it is determined as a fluorescent color. It is characterized by making a judgment.

According to a fifth aspect of the present invention, the determining means detects the background density of the original document, and at least one of the color signals of the pixel of interest is higher than the background color signal, and between the color components. When the difference between the values of is large, it is characterized that it is determined to be a fluorescent color.

According to a sixth aspect of the present invention, the background density is detected by a means for storing each color component value of the background density.
When the input pixel is an achromatic color and the value of each color component exceeds the stored value, the contents of the storage means are updated,
The feature is that the background density is determined when the change width due to the update is small and the update frequency is low.

[0015]

By performing marker editing using fluorescent colors, marker editing such as trimming, masking, color conversion, and composition can be performed with high accuracy not only for black and white images but also for full-color images. As a result, the image editing operation becomes extremely simple and the editing work is further improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram of a color image processing apparatus of the present invention. In the figure, reference numeral 1 is an image input unit for reading R, G, B (red, green, blue) color signals from a color original in multi-values (for example, 0 to 255).
Reference numeral 2 denotes a gradation conversion unit (also referred to as gamma conversion) for correcting a difference in sensitivity of input CCD sensors corresponding to R, G, and B. Reference numeral 3 denotes a fluorescent color identification unit for determining a fluorescent color based on the RGB signal from the image input unit, and 4 denotes Y, M, C, K (yellow) R, G, B values after gamma conversion. , Magenta, cyan, black) color conversion unit for converting 5 values
Is an image processing unit that performs processing such as density adjustment, contrast conversion, pastelization, and posterization on an image, and editing processing such as trimming and masking.
Is an image output unit such as a laser printer.

The operation is as follows. First, a color original is read by the image input unit 1. In the image input section 1, CCDs corresponding to three color components of R, G and B respectively
Read, the electric signals from each CCD are converted into n-value data by A / D conversion, and RGB signals are output. In this embodiment, n = 256 will be described, but n = 128,51
2 or the like may be used.

Further, R, G, B output from the image input unit 1
In many cases, the value of
Is the brightest color, and 0 is the darkest color (in contrast,
In the density linear, 255 is the darkest color and 0 is the brightest color). The reflectance is the ratio (= Ir / Io) of the intensity of the light illuminating the original and the intensity of the light reflected from the original, and the common logarithm of the reflectance is the density (= log (Ir / Io)).
Say.

A color signal having a linear characteristic with respect to this reflectance is called reflectance linear. Normally, a reference white color that is whiter than paper white is provided, and the component value of this reference white is r = g = b = 2.
It is normalized to be 55.

Next, in the gradation conversion unit 2, R, G,
The variation signals of the three B input CCDs are corrected. In gradation conversion, R, G, and B are generally converted independently using a LUT (look-up table) (FIG. 2). This L
UT is defined so that the achromatic color is r = g = b. Also,
In this gradation conversion, an RGB signal having a linear reflectance is often converted into a linear RGB signal having a density. In this case, r =
The lightest color is g = b = 0.

The color conversion unit 4 converts a color signal suitable for output. Generally, the image output device is YMC (or YM).
(CK) ink is output on paper, so RGB to YMC
Conversion to (K) is necessary, and this is performed by the color conversion unit.
This color conversion can be performed by a calculation such as the following equation.

Y = Ary × R + Agy × G + Aby × B + Aay × 1 M = Arm × R + Agm × G + Abm × B + Aam × 1 C = Arc × R + Agc × G + Abc × B + Aac × 1 K = Ark × R + Agk × G + Abk × A + a + A + a + a + a ** is a predetermined constant.

After that, various kinds of image processing are performed if necessary, and the result is output to a printer or the like. The functions of the image processing unit 5 include color correction for adjusting the lightness and darkness and contrast of a document, image processing for mosaicing a pattern, processing an illustration-like or pastel-like pattern, and enclosing with a fluorescent color. Examples include image editing processing for trimming or moving a region, and converting only a predetermined region into another color.

Next, the identification of the fluorescent color which is the subject of the present invention will be described. First, the basic principle of fluorescent color identification will be described. The fluorescent color in this embodiment refers to the color applied to the paper surface with a fluorescent pen or the like. Organic fluorescent materials are widely used in commercially available fluorescent pens and are stimulated by light in the ultraviolet to visible short wavelength range (purple, blue, blue-green),
It has the characteristic that it emits a fluorescent light with a wavelength different from that of the stimulating light (such as red or yellow). That is, the color of a general printed matter is determined only by the reflected light of the irradiated light, whereas the fluorescent color is the color of the reflected light of the irradiated light and the light of the emitted fluorescent light. The difference is that it is fixed.

FIG. 3 shows the result of measuring the spectral distribution under the standard light source (the light source defined by CIE, such as C light source and D65 light source) by applying the orange fluorescent color on a white paper (1 ) And the measurement result (2) of the orange spectral distribution in the printed matter. From FIG. 3, assuming that the reflectance of standard white light is 100%, the color of ordinary printed matter always takes a value of 100% or less, whereas that of a fluorescent color has a reflectance of 100% or more. There is a wavelength range.

The standard light source of the C light source and the D65 light source is 450
It has a peak in light with a wavelength near nm and has a large amount of power in the visible light region (FIGS. 4A and 4B). Therefore, fluorescent colors such as red, orange, and yellow, in which the spectrum of the stimulating light is distributed in the visible region, have particularly high fluorescent emission properties.

From the above, the red and yellow fluorescent colors show a high spectral reflectance of over 100% in a relatively long wavelength region. When such a spectral distribution characteristic is read by a color scanner, the R and G component values become very large values, and pixel data having a color component that does not appear when a general printed matter is input is obtained. For example, since a normal scanner sets the input range so that it becomes a value close to r = g = b = 255 when reading a reference white plate stuck in the scanner, the fluorescence applied on a white paper is determined. When a color is read, a read value of R or G is 255 in a color scanner capable of reading 256 gradations of R, G, and B. As an example, FIG. 5 shows scanner input values for various fluorescent pens.

Therefore, by utilizing this characteristic, the editing area is designated by a fluorescent color such as red or yellow at the time of editing the marker, so that the chromatic color portion of the color document is not misjudged to be the marker color and high accuracy is achieved. It is possible to realize a color manuscript editing function.

Further, when fluorescent light is applied to the background portion of the original having a relatively high paper density, the input level of the fluorescent color is included in the reading range of the scanner. When a document with such a high background density is targeted, the fluorescent color can be accurately identified by whether or not any of the RGB component values is sufficiently large compared to the background area.

According to the present invention, the fluorescent color is identified based on the above principle, and the positional information of the fluorescent color is output,
Various image edits such as trimming can be performed in the image processing unit.

<Embodiment 1> Embodiment 1 is an embodiment in which a relatively white paper is used as a color original and the fluorescent color drawn on the white background is identified. The fluorescent colors are assumed to be those with high fluorescent emission properties such as red, brown, pink, orange, and yellow.

Since these fluorescent colors have high fluorescence in the wavelength range from green to red, the reflectance of R or G takes a very high value as compared with that of the white portion of the paper. Therefore, when there is not much difference in reflectance between the originals, it is possible to distinguish whether the color is fluorescent or not by determining the input values of R and G with the threshold value. Further, since almost no fluorescence is emitted in the blue wavelength region, the reflectance of the B component becomes a relatively low value, similar to ordinary red and orange.

Therefore, assuming that the number of input gradations of the scanner is n and the color signal (when the reflectance is linear) from the scanner of an arbitrary pixel of interest is [r, g, b], r = n-1 or g = n-1 r ≧ Th1 or g ≧ Th2 (r = n−1 or g = n−1) and (b ≦
Th3) (r ≧ Th1 or g ≧ Th2) and (b ≦ T
The fluorescent color can be identified by a simple threshold judgment such as h3). However, Th1, Th2, and Th3 are predetermined threshold values, and for example, Th1 and Th2 are 240 and Th.
3 is 200. FIG. 6 shows the configuration of the fluorescent color identification section when the above determination is used.

When a fluorescent color having a high fluorescent property in the blue wavelength range can be used, the fluorescent color can be identified by the following judgment. That is, r = n−1 or g = n−1 or b = n−1 r ≧ Th1 or g ≧ Th2 or b ≧ Th3 (Th1, Th2, and Th3 are predetermined threshold values, for example, 24
0) The identification of the fluorescent color by the threshold value judgment described above can be applied not only to the color signal of the image input section but also to other color signals such as the RGB density signal after gradation correction and the YMC density signal after color conversion. Is.

<Embodiment 2> In Embodiment 1 described above, the case where the density difference of the paper white of the document is relatively small is targeted.
On the other hand, the second embodiment relates to a method for identifying a fluorescent color when, for example, the density of the paper white of the target document differs depending on the document.

When a relatively white paper is used as a color original and a fluorescent color is applied to the white background, the reflectances of R and G take a very large value as described above, and therefore the fluorescent color is obtained only by the threshold value. It was possible to judge. However, when applying fluorescent color to high density paper such as newspaper,
Since the reflectance of R and G also decreases with respect to the fluorescent color, the threshold for distinguishing the fluorescent color must be reduced. On the contrary, if the threshold value is too small, a problem arises that when a white paper is input, the white background portion is erroneously determined as a fluorescent color.

Therefore, when the background density varies depending on the original, it is necessary to identify the fluorescent color by using a threshold value suitable for the original. In the second embodiment, when various papers are used as color originals, The fluorescent color is identified by detecting the density of the background of the document and detecting the pixels whose RGB reflectance is higher than the detected background.

That is, assuming that the RGB reflectance of the detected background is [rs, gs, bs] and the RGB reflectance of the pixel of interest is [r, g, b], r> rs or g> gs or b> bs At this time, the pixel of interest is determined to be a fluorescent color.

Various methods are conceivable as the method for detecting the background density. For example, the method is performed by performing a prescan to create an image histogram, or by creating a histogram for each line. There are methods, methods specified by the user, and the like.

In this embodiment, a method of making a judgment while scanning is adopted. First, the RGB reflectance of the background of the original is set to [rs, gs, bs]. The values of rs, gs, and bs are sufficiently smaller than those of commonly used paper, for example, rs = gs = bs = 64. Next, while scanning the document, the RGB reflectance is read for each pixel. When the read value is [r, g, b], IF (r, g, b difference value delta (r, g, b) <Th
1) AND (r> rs AND g> gs AND
b> bs) THEN rs = r, gs = g, bs = b and the background reflectance is updated.

As a result, the reflectance of the background is set to rs, gs, and bs when the background of the original appears.
Whether or not the background of the manuscript appears can be known from the fact that the updating width at the time of updating is small and the updating frequency is low. Therefore, the fluorescent color identification is started from the time when the update frequency is low and the update width is small.

FIG. 7 is a block diagram of the second embodiment. The background level determination unit determines the RGB reflectance (rs,
gs, bs) is detected and the comparator (1, 2, 3)
Entered in. In each comparator (1, 2, 3), the RGB reflectance of the pixel of interest is compared with the RGB reflectance of the background, and when r> rs or g> gs or b> bs, the pixel of interest is observable through the OR gate. It is determined and output as a light color.

In this embodiment, a delta (r, g, b) calculation unit for calculating the difference value of r, g, b is provided so that the fluorescent color is not judged to be a white background when the fluorescent color is identified. , The accuracy of judgment is improved. That is, IF (r, g, b difference value delta (r, g, b)> Th
2) AND (r> rs or g> gs or b>
The pixel of interest for which bs) is determined to be a fluorescent color.

As described above, according to this embodiment, even when the density of the background differs depending on the original, the fluorescent color can be identified with high accuracy. The above-described embodiment can be applied not only to the color signal of the image input unit, but also to other color signals such as the RGB density signal after gradation correction and the YMC density signal after color conversion.

[0045]

As described above, according to the first and second aspects,
According to the third aspect of the invention, since the fluorescent color is detected with high accuracy from the document marked with the fluorescent pen, it is possible to edit the marker in the full-color document and to provide special hardware. Without, the image can be easily edited.

According to the fourth, fifth and sixth aspects of the present invention, the fluorescent color can be determined with higher accuracy even when the background density of the original is different.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a color image processing apparatus of the present invention.

FIG. 2 is a diagram illustrating gradation conversion.

FIG. 3 shows reflectance characteristics of orange fluorescence and printed orange.

4A shows a spectral distribution of a C light source, and FIG. 4B shows a spectral distribution of a D light source.

FIG. 5 is a diagram showing scanner input values of various fluorescent pens.

FIG. 6 is a diagram illustrating a configuration of a fluorescent color identifying unit according to the first embodiment.

FIG. 7 is a diagram illustrating a configuration of a fluorescent color identifying unit according to a second embodiment.

FIG. 8 is a diagram showing an example of a color original.

[Explanation of symbols]

 1 Image Input Section 2 Gradation Conversion Section 3 Fluorescent Color Identification Section 4 Color Conversion Section 5 Image Processing Section 6 Image Output Section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06T 7/00 H04N 1/407 1/46 1/60 4226-5C H04N 1/40 101 B 4226- 5C 1/46 Z

Claims (6)

[Claims] 1. A color image processing apparatus having an image input means for reading a color original and inputting color signals of a plurality of colors, wherein the input color signal or another color signal obtained by color-converting the color signal is a fluorescent color. And a means for performing image editing on an area designated by a fluorescent color according to the determination result. 2. The color according to claim 1, wherein the determination unit determines, for each pixel, that the color is a fluorescent color when one or more color signals of the color signals are equal to or more than a predetermined threshold value. Image processing device. 3. The determining means, for each pixel, at least one color signal of the color signals is a first threshold value or more, and another color signal of the color signals is a second threshold value. Below (however,
The color image processing apparatus according to claim 1, wherein the color is determined to be a fluorescent color when (first threshold> second threshold). 4. The determination means detects the background density of a document, and determines that the color is a fluorescent color when at least one of the color signals of the pixel of interest is higher than the background color signal. The color image processing device according to claim 1. 5. The determination means detects the background density of the document, one or more of the color signals of the pixel of interest is higher than the background color signal, and the difference in value between the color components is large. When
The color image processing apparatus according to claim 1, wherein the color image processing apparatus determines that the color is a fluorescent color. 6. The detection of the background density includes means for storing each color component value of the background density, and when the input pixel is an achromatic color and each color component value exceeds the stored value, the storage means is provided. 6. The color image processing apparatus according to claim 4, wherein the content is updated, and the background density is determined when the change width due to the update is small and the update frequency is low.