JP2942282B2 - Digital image processing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image processing apparatus having gradation generating means, and more particularly, to a method for generating external image data so as to simplify a circuit for generating random numbers required for generating gradation. The present invention relates to a digital image processing apparatus that extracts data in the vicinity of the least significant bit and uses the extracted data as a random number.

[Conventional technology]

Recently, the number of digital image processing apparatuses having a function of inserting a gradation pattern into a partial area in a reproduced image is increasing, and the demand is particularly remarkable in the field of color. The gradation pattern is a stripe pattern that linearly increases or decreases at regular intervals in the main scanning direction or the sub-scanning direction.

However, the ability of the recording means (such as a printer) to express the color density on the paper while changing the color density is coarse, and only a slight stepwise density change can be expressed. For this reason, even if a gradation pattern is printed by a simple method, the change position of the color density clearly appears, and a satisfactory aesthetic appearance cannot be obtained. For this reason, a gradation generation circuit has been devised and put into practical use as a means for expressing an intermediate color density in a pseudo manner by an existing printer.

FIG. 15 is a timing chart for explaining the principle of gradation generation, which can be used in common for two cases in which the color density is changed in the scanning direction and the sub-scanning direction. CL
K is a synchronization signal in the main scanning direction and is called a pixel clock.
LSYNC is a synchronization signal in the sub-scanning direction and is called a line synchronization clock, and is generated every time scanning of one line in the main scanning direction is completed. START is a signal for commanding the start of operation of the device.

In the figure, 2) is color data and is basic data for generating a gradation, and is a step-by-step process of 1, 2, 3,... At regular intervals (in this case, every 8 CLK (8 LSYNC)). To increase. There is no intermediate digital value between 1-2, 2-3, 3-4, and 1 is the minimum unit of density change that can be expressed by the printer.

1) is called inclination data and functions as auxiliary data for complementing the color data to obtain smooth data. One step (1/8 in this case) for each CLK (LSYNC).
, And a constant period (color data is 1-2, 2-3, 3-4 ...
Each time it changes), and then increases again by one step.

Therefore, if (1) +2) is obtained, image data whose density is increased approximately smoothly electrically can be obtained, but as described above, this cannot be directly expressed on paper. 3) is random number data introduced to solve this, and is used for the purpose of generating 1/0 at a certain probability determined by the latter value in combination with the slope data of 1). That is, the inclination data changes to 0, 1/8, 2/8, 3/8, etc., and the occurrence probability of 1 is 0, 1/8, 2/8, 3/8, 3/8, 4/8. …
(The occurrence probability of 0 decreases as 1,7 / 8,6 / 8,5 / 8,4 / 8...). Therefore, with a certain probability
If a composite of 1/0 data and color data is supplied to the printer as a gradation, not only an image whose density changes smoothly on paper but also a density component that changes irregularly can be obtained. Is included, creating a unique aesthetic.

The same processing can be applied to the case where the color density decreases linearly.

[Problems to be solved by the invention]

However, in the conventional gradation generation circuit,
In order to generate a random number, it is necessary to separately generate a clock having a cycle different from the above-described image clock.
Special care must be taken to prevent the random number generation state from being synchronous, which has the disadvantage that the circuit configuration is complicated and economically disadvantageous.

The present invention has been made in view of the above points, and it is possible to blur a gradation switching point, avoid a complicated circuit configuration, and improve gradation in a state in which the economics of the apparatus itself are improved. The purpose is to generate.

[Means for solving the problem]

In order to achieve the above object, the present invention selectively selects digital image data of a plurality of color components inputted from outside the device and gradation of a plurality of color components generated by gradation generating means inside the device. In a digital image processing apparatus which sends the image data to an image recording unit, a plurality of color components whose sizes are increased / decreased in a stepwise manner in response to a synchronization signal in a main scanning direction / sub-scanning direction within a fixed period interval. Inclination data generation means provided; random number generation means provided for each of a plurality of color components for extracting data of a predetermined number of bits near the least significant bit of the digital image data of the plurality of color components; Sub-tilt data generation means provided for each of a plurality of color components for extracting data of a predetermined number of bits near the most significant bit; and random number generation means provided for each of the plurality of color components Correcting means provided for each of a plurality of color components that combine the outputs of the stages, add the outputs of the sub-tilt data generating means, and generate 1/0 at a predetermined probability determined by the value of the sub-tilt data in real time And a digital image processing apparatus having the following.

[Action]

By random number generation means provided for each of a plurality of color components,
Data of a predetermined number of bits (hereinafter, referred to as “lower bits”) near the least significant bit of digital image data of a plurality of color components input from the outside of the apparatus is extracted and used as a random number. Further, by a sub-tilt data generating means provided for each of the plurality of color components, data of a predetermined number of bits (hereinafter, referred to as “upper bits”) near the most significant bit of the tilt data (hereinafter, “sub-tilt data”) To be described). The low-order bit data (random number data) of the input image signal for each of the plurality of color components is combined with each other, the sub-tilt data is added, and 1/1 is set at a certain probability determined according to the value of the sub-tilt data.
0 is generated in synchronization with the pixel clock. The method may be a method of adding the two data and extracting the most significant bit of the result, or a method of searching a number table based on a combination of the two data. For this reason, the gradation switching point can be blurred, and a complicated random number generation circuit becomes unnecessary.

Hereinafter, an embodiment of a digital image processing apparatus according to the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are block diagrams showing the basic structure of an embodiment of the present invention. FIG. 1 shows black and white image data, and FIG. 2 shows digital image data for color image data. 1 shows a processing device. Hereinafter, for convenience of explanation, the case of a monochrome image and the case of a color image will be described in parallel.

In FIG. 1, 1m denotes a processing device for a black-and-white image, which performs predetermined processing on multi-valued digital image data input from outside the device (such as an image scanner) and outputs the processed data to an image recording unit. Reference numeral 10m denotes a tilt control unit that generates the above-described color data and tilt data. 11m is a data processing unit which plays a central role in the present invention, and generates a gradation based on color data and inclination data, and selectively selects gradation and input image data at a predetermined timing, and converts the selected image data into an image. It plays the role of outputting to the recording unit. FIG. 2 shows an apparatus for a color image. 1c is a processing apparatus for a color image, and 10R, 10G, and 10B are red (R), green (G), and blue (B) colors. The inclination data control units provided for the image data of the components have the functions shown in FIG.
Same as m. Reference numeral 11c denotes a data processing unit, the function of which is similar to that of 11m in FIG. In the case of processing the image data of the three primary colors in a certain relation with each other, the configuration shown in FIG. 2 is used. However, the image data of the three primary colors is converted into the respective color components (R, G, B components). When processing is performed for each color component, the system shown in FIG. 1 may be prepared for each color component and may be operated independently.

FIG. 3 is a circuit diagram showing a configuration of a tilt controller (corresponding to 10 m in FIG. 1 and 10R to 10B in FIG. 2) for generating color data and tilt data. Reference numerals 200, 201, and 202 denote selectors having a function of selecting input data to the A terminal (B terminal) and transmitting the data to the Y terminal (output terminal) when the data to be input to the S terminal is L (H). Reference numerals 300 and 301 denote up / down counters, which perform an up-count (down-count) operation when data input to the U / ▲ ▼ terminal is H (L). The count target is a pulse train input to the CLK terminal, but the count operation proceeds only when the data input to the EN terminal is H, and when the data is L, the count operation is stopped (does not proceed). ). The count value is output from the Q terminal. The ▲ ▼ terminal is called a load terminal, and the initial value of the count is set by the data input to the D terminal when an L pulse is input from the outside to this terminal (the count operation is performed from the initial value. Is counted).
When the count value of the counter reaches the upper limit (when counting up), an H pulse is output from the RC terminal. Reference numeral 401 denotes a delay flip-flop circuit (DFF), and a constant voltage H is always applied to a D terminal. CL is a clear terminal. In this state, this circuit is cleared, and after the first H pulse is input to the CLK terminal and the output of the Q terminal is changed to H, the output of the Q terminal is output no matter how many times the H pulse is input to the CLK terminal. Is kept at H. The start address of the tilt data is set in the register 100, the tilt data cycle is set in the register 101, and the color data initial value is set in the register 102.

The contents of the signal input from the outside to this circuit are as follows.

CLK: Horizontal synchronization signal (pixel clock), positive logic LSYNC: Vertical synchronization signal (line synchronization signal), positive logic v / h: Selection signal of gradation change direction (vertical / horizontal, H / L) UP / DOWN : Selection signal for gradation increase / decrease (H / L) ON / OFF: Selection signal for gradation presence / absence (H / L) First, set the operation parameters in the following order.

v / h = L (the gradation change direction is the horizontal direction (main scanning direction)) UP / DOWN = H (the gradation is increasing direction) ON / OFF = H (activates the circuit) 201 selects CLK and LSYNC, respectively, and both counters 300 and 301 operate as up counters. Hereinafter, the outline of the operation order will be described.

(1) When LSYNC becomes H (immediately before the start of main scanning), the delay flip-flop circuit 401 is cleared, and the output of the output terminal Q becomes L. Therefore, the selector 202 sets the register 100
(Slope data start address) is selected and transmitted to the counter 300. The counter 300 is loaded with this data.

At the same time, the counter 301 is loaded by the register 102 (color data initial value). That is, the counters 300 and 30
1 performs a counting operation starting from the data of the registers 100 and 102. If the upper limit value of the counter 300 is N and the slope data start address is n, counting from the starting point of the main scan, the data of 100 is not n itself, but N-n.
It is necessary to

(2) At the same time as LSYNC goes low, the input of the EN terminal of the counter 300 goes high, and the counter 300 starts counting in response to the CLK pulse train. When the count operation is repeated n times (when the main scanning target address reaches address n), the count value of the counter 300 reaches the upper limit N, and at the same time, a ripple carrier signal (H pulse) is output from the RC terminal.

(3) The lip carrier signal (H) of the counter 300 is input to the S terminal of the selector 202 via the OR circuit 103. For this reason, the selector 202 selects the gradient cycle data 101 and transmits it to the D terminal of the counter 300, and the counter 3
00 is loaded. In this case, if the inclination cycle is p pixels, the data of 101 needs to be N-p, not p itself.

(4) The ripple carrier signal (H) of the counter 300 is also passed through the OR circuit 103 to the delay flip-flop circuit 401.
, And the output of the Q terminal changes from L to H. The H signal is transmitted to the input terminal of the AND circuit 105.

(5) The counter 300 starts counting operation in response to the CLK pulse starting from Np. The count value is output from the Q terminal as inclination data and functions as inclination data (see FIG. 15).

(6) When the count operation of the counter 300 is repeated p times, the count reaches the upper limit value N, and a ripple carrier signal (H pulse) is output from the CR terminal.
And input to the EN terminal of the counter 301 via. Counter 3
01 can be counted for a moment and becomes 1 in response to the CLK pulse.
Count.

Hereinafter, the same operation is repeated each time the counter 300 repeats the count p times, and the count value of the counter 301 increases by one count. This count value is output from the Q terminal and functions as color data (see FIG. 15).

 Note that the case of FIG. 15 corresponds to the case where the inclination start address n = 0, the inclination period p = 8, and the initial value of the color data = 0.

Next, the configuration and operation of the data processing unit 11m when black and white image data is to be processed will be described with reference to FIG.

113m is a lower bit extraction circuit that extracts a predetermined number of lower bits from the input image data, 112m is an upper bit extraction circuit that extracts a predetermined number of upper bits of the slope data, and 110m is input to the A and B terminals, respectively. This is an adder that adds data and outputs the result from the Σ terminal. As described later, only the most significant bit of the addition result is sent to the next step. 111m is the color data input to the A terminal and the data input to the B terminal (the most significant bit of the Σ terminal output of the adder 110m)
, And outputs the result as a gradation. Reference numeral 310m denotes a selector which selects input data to the A terminal (B terminal) and transmits it to the Y terminal (output terminal) when the area signal input to the S terminal is L (H). As will be described later, the area signal is a signal that changes in H and L2 stages. When this signal is H (L), it indicates that the scanning point is inside (outside) the gradation area.

Here, it is assumed that the number of bits of data extracted by the upper bit extraction circuit 112m and the lower bit extraction circuit 113m are both 2 bits. Here, if the output data (upper 2 bits of the gradient data) of the upper bit extraction circuit 112m is indicated by D _in , D _in becomes 2-bit binary code data. Now, the inclination cycle p (corresponding to p pixels) is divided into four equal parts to obtain four small sections, and the numbers of the p / 4 sections 0, 1, 2, and 3 are sequentially assigned from the left as shown in FIG. Attach.

The value of D _in is the D _in = 00 (p / 4 interval 0) = 01 (p / 4 section 1) = 10 (p / 4 section 2) = 11 (p / 4 section 3). Next, the output of the lower bit extraction circuit 113m is indicated by D _pL . Since the image data includes an error component generated in the optical part of the image reading unit in addition to the noise component, D _pL may be considered to constitute a random number. As described above, when the D _pL is binary encoded data 2 bits, digit data digit and 2 ⁰ of 2 ¹ is a random number that varies independently be 0, 1 are the same each digit of the data Occurs with a probability of 50%. D _pL takes four values, such as D _pL = 00,01,10,11, but for the reasons described above, these values all occur with the same probability.

Therefore, by displaying the output of the adder 110m by D _a, a _{D a = D in + D pL} , specifically, the following values for each p / 4 period. That is, in the p / 4 section 0, D _a = 00 + 00 = 000 (D _pL = 00) = 00 + 01 = 001 (D _pL = 01) = 00 + 10 = 001 (D _pL = 01) = 00 + 11.011 (D _pL = 11), and 2 ² digit of D _a (most significant) is 1 probability 0%
The probability of becoming 0 is 100%.

Then, the p / 4 interval within 1, because it is _{D in = 01, D a =} 01 + 00 = 001 = 01 + 01 = 010 = 01 + 10 = 011 = 01 + 11 = 100 , and the 2 ² digit of D _a is 1 The probability is 25%, and the probability of becoming 0 is 75%.

Then, within the p / 4 section 2, because it is _{D in = 10, D a =} 10 + 00 = 010 = 10 + 01 = 011 = 10 + 10 = 100 = 10 + 11 = 101 , and the 2 ² digit of D _a is 1 The probability is 50% and the probability of becoming 0 is 50%.

Finally, since D _in = 11 _in the p / 4 section 3, D _a = 11 + 00 = 011 (D _pL = 00) = 11 + 01 = 100 (D _pL = 01) = 11 + 10 = 101 (D _pL = 10 ) = 11 + 11 = 110 ( D pL = 11) becomes, D probability 75% 2 ² digit is 1 _a, 0 and becomes the probability is 25%.

Now, if be referred to as a sub inclination data D _cu, 2 of D _a
The digit of ² is 11 or 0 with a constant probability determined by the sub-tilt data (in other words, the number of the p / 4 section).

FIG. 7A shows the structure of the adder 110m in more detail.
In the figure, DI is the aforementioned D _in , DP is the aforementioned D _pL ,
The DA is respectively corresponding to the above-mentioned D _a. Of these, only DA2 is sent to the B terminal of the next adder 111m.

In the fourth view of adders 111m is performed addition of color data and sub-gradient data D _a, from Σ terminal gradation data is obtained, is supplied to the A terminal of the selector 310m.

FIG. 8 is a diagram for explaining the progress of the above data processing. FIG. 8 (a) shows a state in which the color data sequentially increases in the order of 0, 1, 2,. FIG. 7 shows gradient network data finally obtained when a 2-bit random number is used as D _pL . The numbers in parentheses indicate the probability of occurrence of data on the left side outside the parentheses. FIG. 8B shows a case where a random number of 1 bit (only the lowest bit of the image data) is used as D _pL . It is understood that a gradation closer to a linear change can be obtained by increasing the number of bits of the random number.

The case where gradation is generated so that the density is reduced in the scanning direction and the density is reduced in the sub-scanning direction can be dealt with in a manner similar to that described above, and thus the description thereof is omitted.

The role of the area signal in the configuration of FIG. 4 will be described. If the area signal is set to L or H at an appropriate timing in the main scanning direction or the sub-scanning direction, or both, gradation (A terminal input) is obtained by the selector 310m.
And input image data (B terminal input) can be selected and supplied to the image recording unit.
In the embodiment shown in B or FIG. 10, a gradation area can be formed in a part of the reproduced image. The parameters required for this can be set arbitrarily.

Next, a case where the processing target is color image data will be described. In this case, the easiest method is to prepare the three systems shown in FIG. 4 and use them independently to share the processing of the three primary color (R, G, B) image data. As a result, a certain effect can be expected. Since the configuration can be immediately conceived by those skilled in the art, illustration and description are omitted.

FIG. 5 shows a configuration of a data processing section for the purpose of processing the three primary color image data, which is intended to process the data while giving some relation to the three primary color image data. Characters R, G, and B added to the end of the reference numerals in the figure are subscripts indicating that the processing of the R, G, and B components of the image data is shared. The meaning of the numbers 110, 113, 310, etc. is the same as in FIG.

The difference between the configurations shown in FIGS. 4 and 5 is that the method of generating random numbers is different and the number of digits of the adders 110R-B is different. The lower bit data of each of the R, G, B image data is extracted by lower bit extraction circuits 113R-B, respectively.
The signals are transmitted to the B terminals of the adders 110R to 110B, respectively. If the number of lower bits to be extracted is 2 bits, a random number of 64 steps (6 bits) can be obtained. Accordingly, the sub-tilt data D _in
The number of digits is also increased to 6 bits (the slope period is divided into 64). Accordingly, the number of digits of the adders 110R-B also increases as shown in FIG. 7B. Of the # terminals (output terminals) of 110R-B, only the most significant bit is transmitted to the next adder 111R-B.
Now, if one stage of the color data is represented by 1, the change in the color density can be simulated in 1/64 steps.

FIG. 11 illustrates a modification of the configuration in FIG. The configurations in FIGS. 11 and 4 are completely the same except for a part, and the names and functions of the components represented by the same symbols are the same as those in FIG. The difference between the two is that the adder 110m in FIG. 4 is replaced by a number table search means (lookup table) 114m in FIG. That is, it is intended to take in more peripheral data by a number table search method instead of the addition operation.

Also, the contents of the look-up table 114m in FIG. 11 will be described with reference to the example shown in FIG.

In FIG. 14, DA0,1 is inclination data, D0,1 is random number (lower image) data, and DC (c) and DC (d) are output data. At this time, the addition result of the adder 111m with respect to the color data of FIG.
13 (c) and DC (d) are as shown in FIG. 13 (d).

As described above, the minimum unit of the level can be divided according to the number of bits according to the number of bits of the inclination data and the random number data. In FIGS. 13 (c) and 13 (d), since two bits are used, the number of divisions is four. Furthermore, FIG.
This is a case where the number of divisions is 2 using bits.

As shown in the table of FIG. 14, the content of the 114 m look-up table (LTV) can be rewritten to freely change the color data generation ratio.

FIG. 12 is a specific explanatory diagram of the image processing section for color multi-value data in FIG.

This configuration differs from the black-and-white image processing unit shown in FIG. 1 in that color data, tilt data, and input image data have independent R, G, and B components.

The other basic configuration is the same as that of the case of black and white shown in FIG. 2, and only the differences will be described below.

Here, taking FIGS. 7A and 7B as an example, image data lower 2
Use bits as random numbers. When each of R, G, and B is used independently as shown in FIG. 7A, only four values can be expressed.
By using the data of each of R, G, and B as shown in FIG.

Accordingly, with respect to increasing the number of bits of the inclination data of 114R, 114G, and 114B in FIG. 12, the number of random numbers, that is, the number of bits that can be divided, is three times that in the case of black and white.

Although the lower two bits of image data are used in the above embodiment, any number of bits may be used as random numbers.

As described above, in the configuration of the present invention, it is not necessary to form a random number generation circuit by using the lower bits of the image data as random number data. can do.

Also, by using a look-up table for random number data and inclination data, it becomes possible to blur and erase the level change points.

Further, the gradation can be smoothly expressed by using the random number data, and the data and the ratio for generating the pseudo data can be freely set by using the lookup table.

〔The invention's effect〕

As described above, according to the digital image processing device of the present invention, the gradation switching point can be blurred, the complexity of the circuit configuration can be avoided, and the gradation can be reduced while the economical efficiency of the device itself is improved. Can be generated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital image processing apparatus for a black and white image according to the present invention, and FIG. 2 is a block diagram showing a configuration of a digital image processing apparatus for a color image according to the present invention. FIG. 3 is a circuit diagram illustrating a configuration of a tilt control unit that generates color data and tilt data, and FIG. 4 is a circuit diagram illustrating a configuration of an image processing unit that processes black and white image data; FIG. 5 is a circuit diagram showing a configuration of an image processing unit for processing color image data, FIG. 6 is an explanatory diagram showing output data of an upper bit extraction circuit, and FIGS. FIG. 8 is an explanatory view showing the configuration of an adder. FIG. 8 is an explanatory view showing the progress of data processing. FIGS. 9A, 9B, and 10 show a state in which a gradation area is formed in a part of a reproduced image. FIG. 11 is an explanatory diagram shown in FIG. FIG. 12 is a circuit diagram showing another embodiment of the image processing unit according to the present invention, and FIG. 12 is a circuit diagram showing a configuration of an image processing unit for a color image.
(D) is an explanatory diagram showing the progress of data processing, FIG. 14 is a table showing an example of a look-up table, and FIG. 15 is an explanatory diagram showing the principle of gradation generation. Explanation of reference numerals 1c: Processing device for color image 1m: Processing device for black and white image 10R: Slope data control unit 10G ...: Slope data control unit 10B: Slope data control unit 10m: Slope Control unit 11c Data processing unit 11m Data processing unit 100 Register 101 Register 102 Register 103 OR circuit 104 NAND circuit 105 AND circuit 110R Adder 110G Addition 110B Adder 110m Adder 111R Adder 111G Adder 111B Adder 111m Adder 112R Upper bit extraction circuit 112G Upper bit extraction circuit 112B Upper bit Extraction circuit 112m Upper bit extraction circuit 113R Lower bit extraction circuit 113G Lower bit extraction circuit 113B Lower bit extraction circuit 113m Lower bit extraction circuit 200 Selector 201 Selector 202 Selector 300 …… Counter 301 …… Counter 310R: Selector 310G: Selector 310B: Selector 310m: Selector 401: Delay flip-flop circuit

Claims (1)

(57) [Claims] A digital image data of a plurality of color components inputted from outside the device and a gradation of a plurality of color components generated by a gradation generating means inside the device are selectively selected and transmitted to an image recording section. In the digital image processing apparatus, inclination data generating means provided for each of a plurality of color components whose size is increased / decreased in a stepwise manner in response to a synchronization signal in the main scanning direction / sub-scanning direction within a fixed period interval. A random number generating means provided for each of a plurality of color components for extracting data of a predetermined number of bits near the least significant bit of the digital image data of the plurality of color components; and a predetermined bit near the most significant bit of the gradient data A combination of sub-tilt data generating means provided for each of a plurality of color components for extracting data of numbers, and outputs of random number generating means provided for each of the plurality of color components And correcting means provided for each of a plurality of color components for adding the outputs of the sub-tilt data generating means and generating 1/0 at a predetermined probability determined by the value of the sub-tilt data in real time. Digital image processing apparatus.