JP2551542B2 - Copy method - Google Patents

Description

The present invention relates to a copying method for copying an original with a color copying machine.

<Prior Art> Usually, in a copying machine, an original to be copied is mainly a color image having a small number of gradations, a multi-gradation color image original, an original mainly composed of black and white images such as characters, Examples include originals having a black and white image with gradation.

Then, in any original, faithful reproduction or preferable reproduction according to each original is required.

As one of them, it is often practiced to make a black-and-white copy by copying a color original with a black-and-white copying machine. In this case, the background of the color original tends to be dark, and the exposure amount control different from that for the black and white original is required.

Further, Japanese Patent Application Laid-Open No. 57-20749 discloses a method of obtaining a black and white copy by selecting the color of the recording paper in accordance with the background color of the color original.

Thus, it is necessary to distinguish between a color original and a black-and-white original, and Japanese Patent Application Laid-Open No. 60-177367 discloses a method of determining whether or not a color original is obtained by a sensor to obtain a black-and-white copy.

According to this method, the determination is made by detecting a color original document, especially an original document having a colored background, from a black and white original document, depending on what percentages of the R light amount, G light amount, and B light amount are relative to the total light amount of the three colors.
When it is determined that the original is a color original, the copy is automatically performed thinly, and control is performed so that the background density is not increased. In this discrimination method, it is easy to make an error when the image area ratio is small or the image area density is low.

<Problems to be Solved by the Invention> However, the copying method disclosed in the above publication is applied to detect a color original when copying the color original into a black-and-white copy. The faithful reproduction of a color original by black-and-white copying is out of the problem, which is completely different from the problem of copying a black-and-white original by a color copying machine to obtain a copy.

To copy a multi-tone black-and-white original (for example, B / W photo, B / W print, print original, etc.), the gray-scale of a black-and-white copying machine is hard, and the faithful reproduction is insufficient. A color copying machine is intended to reproduce the density and color faithfully to a multi-tone color original document, and has been often used for copying a multi-tone black and white original document.

However, a color image is mainly formed of color materials of three primary colors, and appropriate exposure conditions are set for such an image, while black in a black and white image such as characters is due to black ink and various color materials. In many cases, it is merely visually blackened by mixing, and there is a problem that the black reproduced in the copy is not necessarily black for the copy material under the same copy condition. Further, it has a high ability to discriminate a color difference in a visually neutral color (achromatic color). Therefore, the deviation of the color from the neutral color is conspicuous, and it is necessary to reproduce the accuracy gray that is equal to or higher than that of the color original.

It is difficult to copy a color original and a black-and-white original under the same copying conditions. Further, although it is visually easy to distinguish between a color original and a black-and-white original, it is necessary to classify them because it is forgotten to make a distinction or a black-and-white original has black-and-white images with different coloring materials that are difficult to visually distinguish.

According to the present invention, when an original is copied by a color copying machine to obtain a copy, an appropriate color copying condition can be selected by automatically classifying into a color image and a black and white image, and faithful color reproduction or neutral color reproduction can be achieved. It is an object of the present invention to provide a copying method capable of obtaining a high quality and stable image that is possible.

<Means for Solving the Problems> In order to achieve the above object, the copying method of the present invention is to copy an original having a color image and / or a monochrome image with a color copying machine. Is read, the color image area is determined from the density of the read original, the color image area is classified into at least a color image and a monochrome image according to the characteristics of the color image area, and the color copying condition is set according to the separation of the image. .

<Operation> According to the present invention, the document density of a document having a color image and / or a monochrome image is read, and the color image area is determined from the read document density.

At least a color image and a black-and-white image are classified according to the characteristics of the color image area.

 The copy condition is set according to the classification of the image.

<Example> An example will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a silver salt photographic color copying machine (hereinafter sometimes abbreviated as copying machine) as one embodiment of an image recording apparatus to which the copying method of the present invention is applied.

As shown in FIG. 1, an original 11 is placed on a transparent original placing surface 10 with the original surface facing down, and is pressed down by an original pressing plate 12 whose lower surface is white. In addition, a white reference plate 13 is attached to the lower surface of the left end of the document placing surface 10. The reference plate may be gray or the like instead of white.

The light source unit 14 includes a light source 15, a reflector 16, and a mirror 17.
Built-in, and reciprocating in parallel with the document placement surface 10
Illuminate 11 slits. The mirror unit 18 holds two mirrors 19 and 20 extending in a direction perpendicular to the paper surface,
The light from the light source unit 14 is folded back in parallel. Further, this mirror unit 18 is synchronized with the light source unit 14 in order to correct the defocus due to the movement of the light source unit 14.
Move in the direction of the arrow at the speed of.

The lens unit 22 moves back and forth along the optical axis during magnification conversion. In this lens unit 22, a yellow filter Y, a magenta filter M, and a cyan filter C are arranged near the lens main point between the front group 23 and the rear group 24. These color filters Y, M, C are movable in a direction orthogonal to the optical axis, and the quality of light is adjusted by slit light depending on the insertion amount in the optical path to correct the color balance. Such a filter device is described in, for example, Japanese Patent Publication No. 44-2542. Further, behind the rear group 24, two diaphragm plates 25 and 26 that move in mutually opposite directions are arranged.

In the illustrated example, the two diaphragm plates 25 and 26 are configured to move, but they may be fixed.

In addition to the color filters Y, M and C, an ND filter may be added.

Filters Y, M, C for each color and diaphragm plate 2 as required
As shown in FIG. 3, the drive units 131, 132, 1 are provided at 5, 26.
33 and 134 are provided.

These drive units 131 to 134 may be usually performed by using a pulse motor, a solenoid or the like.

The light that has passed through the lens unit 22 is returned by the mirrors 28 and 29 and then reaches the optical path switching mirror 31 with the axis 30 as the center of rotation. When measuring the reflected light,
Is inserted in the optical path as shown by the dotted line, and the optical path switching mirror 31 is also retracted from the optical path as shown by the dotted line, and the reflected light from the original 11 is condensed into the photometric means 33.

The condensing mirror 32 includes a plurality of mirrors 32a,
As shown in the figure, each mirror 32a is arranged so as to be inclined at an angle corresponding to the distance from the optical axis, and thereby collects almost all or part of the slit light. The photometric means
The reference numeral 33 includes a red sensor 33a, a green sensor 33b, and a blue sensor 33c, and measures the three color light components of the reflected light.

 The control means 50 is connected to the photometric means 33.

The control means 50 controls the color filter Y,
M and C are controlled through their drive units 131-133.

The control means 50 is composed of known control means, and includes a CPU and I
A well-known storage means, together with the / O port, stores a copy condition obtained in advance according to the type of image as described later.

A photosensitive material 36, which is a copying material, is stored in the magazine 35 in a rolled state. This photosensitive material 36 is
When it is pulled out by the pair of pull-out rollers 37 and 38 and then pulled out for a certain length, it is cut by the cutter 39. The cut photosensitive material 36a stops at the position where its tip is bitten by the roller pair 40, 41.

Roller pairs 42 and 43 are arranged opposite to the roller pairs 40 and 41, a slit exposure position is formed between these four rollers 40 to 43, and light from the optical path switching mirror 31 enters.

During copying, the rollers 40 to 43 rotate in synchronization with the light source unit 14, and a processing unit (not shown) for processing the exposed photosensitive material 36a is installed. In this processing section, development, bleaching,
Each processing of fixing and washing is performed.

A take-out tray (not shown) for feeding the dried photosensitive material 36a is provided in the downstream of the processing section.

Next, setting of copying conditions will be described with reference to FIG.

At the time of condition setting, a mode designation key (not shown) is operated to enter the copy condition setting mode.

Next, set the document 11 on the document placement surface 10, and then
A copy key (not shown) is operated. In this copy condition setting mode, the color filters Y, M and C and the diaphragm plates 25 and 26 are set at standard positions. The condenser mirror 32 is inserted in the optical path as shown by the dotted line, and the optical path switching mirror 31 is retracted to the position shown by the dotted line. After that, the light source unit 14 and the lens unit 22 move in synchronization, and the reference plate 13 and the original document are moved.
11 and are illuminated with slit light to perform scanning.

Reflected light from the reference plate 13 and the original 11 is reflected by the mirrors 17, 19
~ 20, the lens unit 22, the mirrors 28, 29 in this order, and then enters the condenser mirror 32. As shown in FIG. 2, the condenser mirror 32 condenses almost all or part of the slit light and guides it to the photometric means 33. The photometric means 33 includes a red sensor 33a, a green sensor 33b, and a blue sensor 33.
Since it is composed of c and c, the three color components of the reflected light are measured respectively.

The signal of the light amount output from each of the sensors 33a to 33c is logarithmically converted, and this value and the logarithmically converted value of the photometric value of the reference plate 13 are converted into a density signal to obtain the original density of the original 11.

 Then, the document density is stored.

As the value corresponding to the photometric value, for example, a logarithmic conversion value of the photometric value, a functional expression corresponding to brightness, or a conversion value by a conversion table may be used.

The color image area is determined from the density of the original read as described above.

Specifically, the color image area may be determined by the color deviation from the neutral color (achromatic color) having a certain value or more. At this time, in some cases, the color density may be calculated based on the read document density and then determined.

As an index showing this color bias, for example, (R-C _Rmin ) + (G-C _Gmin ) + (B-C _Bmin ) [where C _Rmin , C _Gmin , and C _Bmin are R, G, and B Represents the logarithmic value of the photometric value of each color, and represents the minimum value of R, G, and B. ] Or the like may be used.

Not limited to the above example, a value corresponding to a difference from a constant color (for example, a neutral color) can be used as the color deviation.

 Specifically, saturation, hue, etc. may be applied.

As the saturation, | (RW) + (GW) + (B-
W) | _{[where, W = (k 1 R +} k 2 G + k 3 B) / (k 1 + k 2 +
k ₃ ), and k ₁ , k ₂ and k ₃ each represent a constant. ], | (R−G) | + | (B−G) |, | R−G | + | G−B |, (R−G) ² + (B−G) ² , and (R / G + B / G ), [In the above, R, G, and B have the same meanings as described above. ], Each value shown in [], the chroma value in the CIE color system, and the value determined from the color coordinate table can be used.

Further, as the hue, the value determined from the value of (RG) / (GB), the angle in color coordinates, the angle of the coordinate point in the chromaticity diagram, the color change of the color coordinate table, etc. is used as a reference. And it is sufficient.

As described above, after determining the color image area, the original 11 to be copied is composed mainly of at least a color image based on this color image area (hereinafter, color original)
It is determined whether or not the document is composed of a monochrome image (hereinafter, a monochrome document), and the document is classified.

In such classification, as shown in FIG. 5a or 5b, for example, the color image area (shown in the figure) is determined from the relationship between the saturation and the document position, and the saturation of the color image is determined. The threshold value (k _c ) is used as a reference to determine the portion determined as the color image area.

This determination may be performed by comparing the ratio of the color image area to the entire area or the color image area itself with the threshold value as a reference, in terms of area, number, distance or the like, or ratio, distribution or the like. In addition, as a matter of course, when the color image area does not exist, it is classified as a monochrome original.

Based on such a judgment, those shown in FIG. 5a are classified as color originals and those shown in FIG. 5b are classified as black and white originals.

As shown in FIG. 5b, even a black-and-white document may appear highly saturated. This is because when the image density is high, the color of the original is not necessarily a neutral color, the accuracy of the photometric system, and the difference in the spectral sensitivity distribution between the naked eye and the photometric system.
It is considered that even if the color is neutral to the naked eye, it may not be neutral due to photometry.

On the contrary, a color original may not be determined as a color image area. The cause is that when a color of two or more different colors happens to have a color close to a neutral color, when a low-density or high-density image does not have a high saturation, the neutral color including a white background causes a background color. This is the case when the color image portion occupying a large area is small, the background portion, the character portion and a part of the black and white image are included. Therefore, it is erroneous to judge the monochrome image power of a color image based on the average value of mere photometric values, the color of some photometric values, or the color balance of the three primary color values.

 The present invention eliminates such drawbacks.

In the above, only the originals are classified as color originals or black-and-white originals, but they may be further classified according to the type of color image in the color originals or the type of black-and-white image in the monochrome originals.

That is, the color images may be further classified according to photographs, prints, illustrations, or the like, or may be classified according to color materials, gradations, or the like. Such classification may be performed by analyzing the image area of the document and, conversely, by analyzing the non-image area.

Similarly, a monochrome image may be further classified into a character image, a multi-tone image, and the like.

For this reason, it is possible to classify a color image and a black-and-white image even for a document having both of them according to their characteristics.

In addition to the above-described features of both, when the photometric means 33 is capable of photometry of three or more colors, it is possible to accurately separate from the more detailed features.

For example, by using a 700 nm photometric sensor for three colors of 450 nm, 550 nm, and 650 nm, a black and white image composed of a silver image or a black plate and a coloring material having no absorption above about 700 nm found in paints are created. Black and white images can be separated. In this case, even if the image is a black and white image, the copying conditions of the two are different.

In addition to the above three color photometric sensors, 500nm, 600nm,
By using photometric sensors with different wavelengths such as 700 nm, it is possible to accurately determine whether the image is a color image or black and white image composed of three dyes, or silver or black plates.

After classifying the originals as described above, the optimum copying conditions determined in advance according to the classification are selected and the color copying conditions are set.

Such a color copying condition may be defined as an exposure amount according to the type of color image or the type of monochrome image,
For example, as shown in FIG. 4, copy conditions 1, 2, and 3 may be set.

The above-mentioned exposure amount may be obtained in advance by using a reference plate or a test chart and stored (Japanese Patent Application No. 62-37249, 6).
2-37250, etc.). Alternatively, the copy condition may be determined as a corrected exposure amount for the copy condition such as a color photographic original or a color printed original. Further, the copy condition based on the classification of the black and white image type in the black and white original document may be modified according to a predetermined condition depending on the tint of the photometric value.

For example, when the photometric value at 700 nm has a density smaller than 650 nm, the copy tends to be red, so it is preferable to set the copy condition such that the red exposure amount is smaller than the copy condition for the black and white original.

The exposure amount can be controlled by the light emission amount, the scanning speed, the aperture opening amount, etc., in addition to the above-described filter movement amount.

After setting the copy conditions, a mode designation key (not shown) is set to the copy mode. In this copy mode, the condenser mirror 32 is retracted from the optical path, and the optical path switching mirror 31 is inserted into the optical path. Next, a copy key (not shown) is turned on to create a color copy. In this case, the photosensitive material 36a is exposed in the course of the light source unit 14.

In the above description, a silver salt photographic color copying machine is cited as the image recording apparatus, but the image recording apparatus is not limited to this. An electrophotographic color copying machine, a heat transfer type color copying machine, an ink jet color copying machine, a laser. It may be a color copier or a video color copier.

<Effect of the Invention> According to the present invention, since the color image area is determined from the color document density by reading the document density of the document, it is possible to accurately classify the document according to the type of image. Then, the color copying condition can be selected based on this accurate classification, and a high quality and stable copied image can be obtained.

In copying a color image, a copying condition can be set by a color material or the like, and a monochrome image can be copied by a color copying machine with a good color balance.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a silver salt photographic color copying machine to which the present invention is applied. FIG. 2 is a sectional view showing the action of the condenser mirror. FIG. 3 is a block diagram for explaining a method of setting copy conditions. FIG. 4 is a flowchart for explaining the flow of setting copy conditions. FIGS. 5a and 5b are graphs for explaining the classification of images. Explanation of reference numerals 10 …… Original placement surface, 11 …… Original, 12 …… Original pressing plate, 13 …… Reference plate, 14 …… Light source unit, 22 …… Lens unit, Y …… Yellow filter, M …… Magenta filter, C ... Cyan filter, 31 ... Optical path switching mirror, 32 ... Focusing mirror, 33 ... Photometric means, 36, 36a ... Photosensitive material, 50 ... Control means

Claims (1)

(57) [Claims] 1. A copying method for copying an original having a color image and / or a black-and-white image by a color copying machine, the original density of the original is read, and a color image area is determined from the read original density. A copying method characterized by classifying at least a color image or a black-and-white image according to the characteristics of the area and setting a color copying condition according to the classification of the image.