JPH0364268A - Color copying device - Google Patents

Abstract

PURPOSE:To exactly decide color/black-and-white documents with regard to a document of an arbitrary shape by providing a document position detecting part and a color deciding part. CONSTITUTION:An output picture signal G2 of a shading correcting part 102 being a picture signal for detecting a document position and output picture signals R3, G3 and B3 of a shift memory part 103 being picture signals for deciding a color are controlled so that G2 becomes earlier by a 2-line portion in the shift memory part 103. Therefore, by reading the number of count of a chromatic picture element based on R3, G3 and B3 by a color deciding part 112 after two lines after setting a document section detected from the signal G2, a document position and a chromatic deciding section coincide with each other. When sampling is ended, when the total number of chromatic picture elements/total number of sampling object picture elements is larger than a prescribed value gamma, a color copy is executed, and when it is smaller, a black color copy is executed. In such a way, even against the documents of various shapes, the decision of black-and-white document/color document is executed exactly, and the copy time is shortened and the expenses is curtailed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color copying apparatus, and particularly to a color copying apparatus having a function of automatically determining whether a document is a monochrome document or a color document.

[Conventional technology]

Conventionally, color copying machines automatically determine whether a scanned original is a black-and-white original or a color original, perform black monochrome copying for a black-and-white original, and use four colors (yellow, magenta, cyan, and black) for a color original. Techniques for performing copying are known. This makes it possible to shorten copy time and reduce costs.

[Problem that the invention is trying to solve]

However, in the above-mentioned conventional example, since the entire surface of the document was the subject of determination, accurate determination could not be made for irregularly shaped documents or areas.

[Means to solve the problem]

The present invention has been made in view of the above-mentioned drawbacks, and is intended to perform black-and-white/color document determination faithfully to the document shape and region shape.

〔Example〕

FIG. 2 shows an overall configuration diagram of a digital color copying machine to which the present invention is applied.

An image scanner unit 201 reads a document and performs digital signal processing. Further, 202 is a printer unit, which prints out an image corresponding to the original image read by the image scanner unit 201 on paper in full color.

In the image scanner unit 201, 200 is a mirror pressure plate, and an original 204 on an original platen glass (hereinafter referred to as a platen) 203 is irradiated by a platen 205, and a mirror 206,
207 and 208, an image is formed on a three-line sensor (hereinafter referred to as CCD) 210 by a lens 209, and is sent to a signal processing unit 211 as full color information red (R), green (G), and blue (B) components. In addition, 205 20
6 is the speed V, 207. 208 scans the entire surface of the document by mechanically moving in a direction perpendicular to the electrical scanning direction of the line sensor at 1/2v.

The signal processing unit 211 electrically processes the read signal to produce magenta (M), cyan (C), and yellow (Y) signals.

The printer unit 202 decomposes black (Bk) into each component.
send to Furthermore, for each document scan by the image scanner section 201, one of M, C, Y, and Bk components is sent to the printer section 202, and one printout is completed by scanning the document four times in total.

M sent from the image scanner unit 201.

The C, Y or Bk image signal is sent to the laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the image signal. The laser beam scans the photosensitive drum 217 via a polygon mirror 214, an f-theta lens 215, and a mirror 216.

Reference numeral 218 denotes a rotary developing device, which is composed of a magenta developing section 219, a cyan developing section 220, a yellow developing section 2211, and a black developing section 222. Develop the electrostatic latent image with toner.

223 is a transfer drum, and paper cassette 224 or 225
The paper fed from the transfer drum 223 is wound around the transfer drum 223, and the image developed on the photosensitive drum 217 is transferred onto the paper.

After the four colors M, C, Y, and Bk are sequentially transferred in this manner, the paper passes through the fixing unit 226 and is discharged.

FIG. 1 shows a block diagram of a color copying apparatus to which the present invention is applied, and will be described below.

The CCD reading section 101 has R (red) and G (green).
, B (blue) analog color signals, an amplifier for amplifying each color, and an A/D converter for converting into an 8-bit digital signal. The signal subjected to shading correction for each color in the shading correction unit 102 is corrected for the deviation between two pixels between colors in the shift memory unit 103, and then sent to a color determination unit 112 (described later) and a LOG conversion unit that performs logarithmic correction for light density conversion. 104
sent to.

Density signals Y (yellow), 2M (magenta), and C (cyan), which are output from the LOG converter 104, are input to a black generator 105, and a black signal (Bk) is generated. Bk is generated from, for example, Min (Y, M, C). Furthermore, in the masking/UCR section 106, the filter characteristics and toner density characteristics of the color sensor are corrected and removed from the output Y, M, C, and Bk signals of the black generation section 105, and then the developed signal of the four color signals is removed. One color is selected.

Next, the density conversion unit 107 converts the density according to the development characteristics of the printer and the operator's preference, and the trimming processing unit 108 edits a desired section, and then sends it to the printer unit to form an image.

A synchronization signal generation unit 109 uses a horizontal synchronization signal BD (beam detect) signal and a vertical synchronization signal ITOP (image top) signal synchronized with the printing of each line sent from the printer inside the image scanner. A horizontal synchronization signal HSYNC, a pixel synchronization signal CLK, etc. are generated and sent to each processing unit and CPU.

Original position detection unit 1. In lO, the position and size of the document are detected based on the binary signal of the green (G) signal after shading correction. Also, the magnification/movement processing section 111
controls the writing of data into the shift memory, the reading cycle and timing, and realizes scaling and movement of the image.

The CPU section 113 is a microprocessor - other known 11
0 circuit, a timer circuit, an interrupt control circuit, a serial communication circuit, a ROM, a RAM, etc., and controls each of the above-mentioned processing units. Further, the CPU section 113 controls a pulse motor 114 that drives the optical system, a document illumination lamp 115, a sensor 116 that detects the position of the optical system, and an operation section 117.

Next, document coordinate detection in the document position detection section 110 will be described.

As described above, the pressure plate 200 is mirror-finished, and the reflected light obtained by illuminating the pressure plate is specularly reflected and is not focused on the image reading sensor, resulting in a black level in terms of brightness.

Further, the background of a normal document is white, and its image signal has a white level in terms of brightness.

Therefore, as shown in FIG. 5, the position of the document placed on the platen can be detected by detecting the position of the white signal among the black signals shown by the hatched area.

In this embodiment, the light source system points the reference point SP on the platen.
While scanning in the entry direction from to the rear end, select any sub-scan position [
The main scanning positions XS and XE of the document at Yi are detected.

FIG. 4 shows the logic for detecting the coordinates and will be described below.

The main scanning counter 401 is an up counter and represents the scanning position in l main scanning lines. This counter is reset by the horizontal synchronizing signal HSYNC, and counts up every time the image data clock CLK is input.

The image data VIDEO, in which the G (green) signal after shading correction is binarized, is stored in the shift register 402.
Input in bits. When the 8-bit input is completed, the gate circuit 403 checks whether all 8 bits are a white image, and if YES, outputs "1" to the signal line 411.

In each main scan line, flip-flop 410 is set when the first 8-bit white appears. This flip-flop is reset in advance by the H3YNC signal. After that, it remains set until the next HSYNC comes.

When the flip-flop 410 is set, if the EN signal output from the CPU is "1", the gate 404 outputs "1", so the latch 409 stores the current main scanning counter 4.
A value of 01 is loaded and becomes the Xs coordinate value.

Further, each time the gate 403 outputs 1, the value of the main scanning counter 401 is loaded into the latch 405.

When the value from the main scanning counter when the first 8-bit white appears is loaded into the latch 405, it is compared in magnitude with the data in the latch 408 by the comparator 406.
Since the data is larger, the signal E output from the CPU 113
When N is 1, data in latch 405 is loaded into latch 408. This operation is processed until the next 8-bit VIDEO enters the shift register 402.

If this comparison operation between the latches 405 and 408 is continued during one main scanning line, the main scanning coordinate at which 8-bit white appears last in the main scanning direction remains in the latch 408, and this becomes the XE coordinate value.

FIG. 6 shows an example of a timing diagram related to coordinate detection.

The horizontal synchronizing signal HSYNC(1) also corresponds to the effective section of the image, that is, in this case, the main scanning section of the platen. At each falling edge of this HSYNC (1), the CPU 11
3, an interrupt signal lNTl (2) is generated.

The CPU 113 moves the optical system in the sub-scanning direction, and when it detects that it has reached the reference point SP (5), sends an EN signal (3).
Turn on. The detection circuit shown in FIG. 4 performs the detection operation in units of H3YNC intervals during the ON interval of the EN signal.

On the other hand, when the CPU 113 turns on the EN signal (3),
Count the HSYNC interrupt lNTl twice and turn off the EN signal. This is because the ON timing of the EN signal is H.
This is because there is no guarantee of synchronization with SYNC, and correct detection over the entire main scanning period cannot be performed in P(4), which is the detection period from turning on the EN signal to the first interrupt lNT1. The aforementioned coordinate values XS and XE taken in by the second lNTl interrupt after the ENN signal N are reliable because they are the detected coordinates in the detection section Q(4) covering the entire main scanning section. After capturing the detected coordinates, turn on the EN signal and start the next INT.
Wait for 1 and then repeat.

With the above configuration and control, any sub-scanning position Yi
The main scanning sections XS and XE of the original can be detected.

The contents of the color determination section (112 in FIG. 1) are shown in FIG. 3A and will be described below.

The R, G, and B signal components for a certain pixel read out from the shift memory section 103 are input to the maximum value detection circuit 301 and the minimum value detection circuit 302, and from each circuit MAX=
max (R, G, B), M I N = min
(R, G, B) is output. In this embodiment, MAX, MI
An output of 6 bits each is obtained.

Next, MAX and MIN are both lookup table LUT
303, and as a result, a 1-bit color determination signal IRQ is obtained. LUT303 is shown in Figure 3(B).
Indicates the content of In the two-dimensional plane composed of inputs MAX and MIN, area A is determined to be achromatic and outputs “0”.
Area B is determined to be a chromatic color and "1" is output.

The determination signal IRO obtained in this manner is input as a clock to the counter 304.

The counter 304 is reset by the horizontal synchronizing signal HSYNC, and counts the number of chromatic color determination pixels of the determination signal IRQ within the interval permitted by the GATEA signal, which is the output of the flip-flop 306 in one main scanning line. This count value is read out by the CPU 113 via the latch 305.

Flip-flop 306 is set by the count-up signal of ST counter (start bit counter) 309 and reset by the count-up signal of EN counter (end bit counter) 310, and generates count permission signal GATE for counter 304.

ST counter 309 and EN counter 310 are each CPU
counts down the count values written in latches 307 and 308.

As described above, the number of chromatic color determination pixels in an arbitrary section of each main scanning line can be counted.

FIG. 7 shows the control procedure of the first embodiment, and will be explained below.

First, a counter K on the RAM as an accumulation counter for the number of chromatic pixels is initialized to O, and a counter P on the RAM as an accumulation counter for the number of pixels to be sampled is similarly initialized to 0 (701). Next, the determination interval signal GAT described in FIG.
As the load values of the two counters ST counter and EN counter for E generation, a value larger than l main scanning period is set to a state in which the GATEA signal is not output, and O is set to flag F on the RAM as a flag indicating the state. Set it ((702).

Start moving the light source system by turning on the lighting lamp 70
3) When the platen reference point SP is reached (704).

Turn on the EN signal mentioned above (705), then turn on HS
Wait for the second interrupt signal lNTl due to the fall of YNC (706), and turn off the EN signal (707).
).

When the flag F indicating the control state of the GATEA signal in the previous interrupt processing is 1 (708), that is, if a sample valid period is set, the count value of the counter 304 in FIG. The number of read chromatic pixels is set in the buffer K on the RAM (709).

When K is larger than a predetermined value α (710), it is added to the above-mentioned integration counter K (711).

This comparison with α is the simplest example of noise detection. If F is O in (708), it means that the counting operation is not being performed and the count value is not read.

Next, the document positions XS and XE are read from the two latches 409 and 408 in the document position detection circuit shown in FIG.
3) Assuming that the original has been detected, XS and E are set as the load values of the ST counter for the next chromatic pixel count period.
XE is set as the load value of the N counter, and the aforementioned flag F is set to 1 (714).

Furthermore, XE-XS is added to the above-mentioned integration counter P as the total number of pixels in the count period targeted for counting the number of chromatic pixels ((715). If XE-XS is smaller than β, the document is detected. If this is not possible, the ST counter and EN counter are set to a value larger than one main scanning section, and the flag F is set to 0 in order to prohibit counting of the number of chromatic pixels ((716)).

The above controls (705) to (716) are repeated until the optical system reaches the rear end of the platen (717). When it reaches EP, the lamp is turned off, the optical system is returned to the starting point (718), and the sample is sampled. Finish the action.

Shading correction unit 1 which is an image signal for document position detection
The output image signal G2 of 02 and the output image signals R3 and G3B5 of the shift memory unit 103, which are image signals for color determination, are controlled in the shift memory unit 103 so that G2 is accelerated by two lines, so they are detected from 62. Two lines after setting the original section, R3°G3. By reading the chromatic pixel count based on B, 3, the document position and the chromatic determination section match.

After completing the sample, it is determined whether /P, that is, the total number of chromatic pixels/the total number of pixels to be sampled, is greater than a predetermined value γ (719), and if it is, a color copy is performed (720).
, performs black copying when it is small (721).

As described above, it is possible to accurately determine whether a black-and-white document or a color document is a document of various shapes, which is effective in shortening copying time and reducing costs.

Furthermore, this embodiment sequentially recognizes the document sections while scanning the document and dynamically matches the chromatic judgment sections.
It does not require a large capacity memory, and is efficient as it only requires -1 sample scans.

Also, the judgment condition K/P > γ is just an example, and is simply K/P > γ.
There is also a method of comparing the value with a predetermined value.

While the first embodiment is for an irregularly shaped document, the second embodiment described below is an example of processing for a non-rectangular area input by an operator.

A conceptual diagram thereof is shown in FIG. 8 (8-1) and will be explained below.

When copying only the inside of a triangular area generated by connecting the point sequences PO, PL, and P2 sequentially inputted by the operator using the digitizer 118, black and white/color determination is performed for images only inside the triangular area. It is. In this case (8-1), as shown in the figure, the section indicated by the arrow in each main scanning line may be used as the judgment section. For example, at the main scanning position Yi, XS, ! : Between XE.

The difference between this second embodiment and the first embodiment is whether or not the sample area is known in advance.

The control procedure of the second embodiment is shown in FIG. The operator uses the digitizer 118 to select point P as shown in FIG. 8 (8-2). + Pl... Each time you input PN, the coordinates of each point (X
o+ yo)+ (x++ y+),...(XN, 3
'N) in the area coordinate table on the RAM as shown in Figure 1O in the input order.
).

After entering all the necessary points (SP502), 1st I
A line segment table as shown in the figure is created in an area on the RAM (SP503). A line segment table is created corresponding to each line segment surrounding the area.

For example, for an area as shown in FIG. 8-8-2, a line segment connecting point Po and point Pl is used. , the line segment connecting point Pl and point P2 is L
11 and below in the same manner as L2. ...A total of N+1 line segments are defined as LN, and a line segment table as shown in FIG. 11 is created for each line segment. However, a line segment table is not created for line segments parallel to the main scanning direction, that is, when )' l =Y +++.

Here, we will add a detailed explanation of the line segments and the contents of the table.

Line segment Ll is a line segment connecting point P and point P +++. At this time, the line segment start sub-scanning coordinate Y St is min (YY
i++), and the line segment end sub-scanning coordinate Y Ei is m
a x (Yl, Y+++).

In addition, the line segment start main scanning coordinate X si is YSI
When , it is Xl, and when YSI is Y1+1, it is x1+1.

For convenience, the one of X + and X +++ that is not X Si is assumed to be X Ei.

The integer part of the line segment slope is (XEI-Xst) / (YE
I-Yst), and the fractional part is X El -X s
r = K I + (Y El - Y si ) + DX,
DX+ that satisfies D Y + = Y El −Y
The DY required by si is powerful. EX、、、XBO
l, X1io is the RA used during the actual copy operation
This is a temporary buffer on M.

The processing content Ti is either on the start side (T+=0) or on the end side (T
I=1).

When the creation of the line segment table at P503 in FIG. 9 is completed and the start of copying operation is instructed by the operation unit 109 (S
P504), the three buffer slope calculation buffers EX in FIG. 11, processing coordinate buffers X BOi , X B1
1 together (5P505), scan the area for black and white/color judgment as described below (SP506), use the result as a basis (SP507), and make a black copy (SP50).
8) performs color copying (SP509).

FIG. 12 shows a control procedure for black and white/color determination scanning.

First, counter C on the RAM that counts the sub-scanning position
NT is set to O (901), and then area K on the RAM is integrated with the total number of chromatic pixels and the total number of sample pixels.

Set P to 0 (902). A value larger than one main scanning interval is set in the above-mentioned judgment interval generation ST counter and EN counter to prohibit the output of the GATE signal, and the flag F indicating this state is set to O (903). Turn on the lamp and start the optical system (904), and when it reaches the reference point SP (905)
), wait for the aforementioned lNTl interrupt (906), and when the interrupt occurs, when the GATE signal status flag F is 1 (90
7) Read the number of chromatic pixels from the counter 304 in FIG. 3, set it in the buffer K on the RAM (908), and add it to the integration counter K (909).

Next, the sub-scanning counter CNT on the RAM is incremented by "1" (910), and then the above-mentioned line segmentation is performed. to LN (912) Set O to the counter i on the RAM that counts line segments in order to perform the following check (911
). Check whether line segment Ll includes current position CNT by Ys+<
Check with CNT<YE+912°913),
If not included, go to ■. When the line segment L+ corresponds to the current position, processing is performed to discretely calculate and generate line segments with arbitrary slopes from (914) to (919).

As mentioned above, the slope of the line segment is the integer part Kl and the fractional part DX/D.
Since it is defined as Y+, each time the sub-scanning coordinate advances by l, the main scanning coordinate advances by at least Kl (916.918).

For the fractional part, each time the sub-scanning coordinate advances by 1, the numerator DX+ is added to the temporary buffer E
915), and when the sum becomes greater than DY+ (914), the main scanning coordinate is advanced by l (91B).

At that time, DY+ is subtracted from the temporary buffer EX+ (917). Also, temporary buffer EX+
is initialized to 0 before starting sub-scanning.

The main scanning coordinate BUF obtained as described above is set in the calculation buffer XBOi for the next interrupt processing ((919)).

Next, check TI (920)) If TI is O, the line segment is on the start side of the area in the main scanning direction, so the ST counter that controls the start of the judgment section (Fig. 3, 30)
9), set BUF as the load value of 921), T
When 1 is 1, it is the end side of the area, so the EN counter (
BUF is set as the load value in FIG. 3(A) 301) (924).

Also, for calculation of the number of sample pixels, if the set BUF value is the start, it is area n on the RAM, and if it is the end, it is RA.
Set it in area m on M ((922°925).

Also, when starting, the flag S on the RAM indicating that the T counter and EN counter have been set is bi+0.
When is the end, set bi+1 to '1'' (923°92
6).

When start and end are set, flag S becomes 3.
(927), the total number of samples counter P is (m
-n) (931), and sets flag F to 1 indicating that the GATE signal control state has been entered (932).

If S is not 3 (927), check whether all line segments have been examined (928), and if not completed, increment the line segment counter i (929) and return to (2). When all line segments are checked, the current position is 1i1cNT
Since there is no corresponding line segment, the ST counter,
Set the load value to a value that will not cause the EN counter to count up, and set the flag FO (930
). If 1 or O is set in F, the temporary flag S is set to 0 (933), one interrupt processing is completed, and the above operations (906) to (933) are performed until the optical system reaches the end EP. Repeat (934).

After that, the optical system is returned to the starting point (935),
Same as the first embodiment described above (when K/P is larger than the predetermined value γ, color (937) is determined, and when it is smaller, black and white is determined (937).
38).

1st. Although the second embodiment relates to means for determining black and white/color of a copy target area, the idea of the present invention can be applied to all means for detecting feature quantities of a document.

As a third embodiment, an original document will be explained as another example of the feature amount.

For example, the G (green) output of the shading correction section 102 in FIG. 1 is input to the latch 601.

The output of latch 601 is sent to comparator 602,
It is compared with the output of the video signal latch 605 more than a clock earlier, and when the output of the latch 601 is large, the output l" is sent to the gate 603. At the gate 603, the interval signal GATE explained in FIG. 3 and the output of the comparator 602 are both "
1'', the selector 604 sends the output of the new video signal latch 601 to the latch 605.

By continuing the above operation for one main scanning line, latch 6
The maximum density between them is latched at 06 and can be read by the CPU 113.

Using the same procedure, the comparator 607, gate 608, selector 609, and latch 610 detect the minimum density in the main scanning line, and the CPU 113 reads it out via the latch 611.

As a result of executing the above processing during a predetermined sub-scanning section, CPU1
13 creates an optimal density conversion curve from a histogram composed of the maximum and minimum densities within a predetermined area, and
This can be applied to the density converter shown in FIG. 107.

1st. By applying the density detection function described above in place of the document black and white/color determination function of the second embodiment, it is possible to detect the density of an image inside an irregular shape or a non-rectangular area set by the operator. The effect of being able to do these things with one sample scan is also obtained.

〔Effect of the invention〕

As described above, it is now possible to accurately determine whether a document area of an arbitrary shape is a color document or a black and white document.

Furthermore, the above effects are made possible without using a large capacity memory.

Further, according to the present invention, it is possible to detect the coordinates of the document and determine whether the document is color/black and white with one sub-scan.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a color copying apparatus according to the present invention, FIG. 2 is a sectional view of the color copying apparatus, FIG. 3(A) is a block diagram of a color determination section, and FIG. 3(B) is a color determination table. Figure 4 is a block diagram of the document position detection section, Figure 5 is an explanatory diagram of the first embodiment, Figure 6 is a timing diagram of the first embodiment, and Figure 7 is a diagram of the first embodiment. FIGS. 8, 10 and 11 are explanatory diagrams of the second embodiment, FIGS. 9 and 12 are control flowcharts of the second embodiment, and FIG. 13 is an explanatory diagram of the third embodiment. It is an explanatory diagram of an example, and 101 is CO
D reading section, 112 is a color determination section, 110 is a document position detection section, and 113 is a CPU section. Crime 8 Figure Cg-Z)

Claims (5)

[Claims] (1) A color copying apparatus characterized by determining whether a copying target area of an arbitrary shape located at an arbitrary position is a monochrome image or a color image, and performing a copying operation based on the determination result. (2) In claim 1, the invention is characterized in that the main scanning coordinates of the document at an arbitrary sub-scanning position are detected, and the determination as to whether the image is a monochrome image or a color image is controlled based on the detected detection coordinates. Color copier. (3) A color copying apparatus according to claim 2, characterized in that a main scanning determination section at an arbitrary sub-scanning position can be dynamically changed in accordance with sub-scanning. (4) A color copying apparatus that detects the feature amount of an image in an arbitrary-shaped copying target area located at an arbitrary position, and performs a copying operation based on the detection result. (5) Color copying according to claim 4, characterized in that the main scanning coordinates of the document at an arbitrary sub-scanning position are detected, and the determination of the feature amount of the image is controlled based on the detected detected coordinates. Device.