JPH0679336B2 - Image processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image processing method for converting an image.

<Prior Art> Conventionally, as one of the image processing methods of this type, an electronic plate making technology in the printing industry and a professional lab technology applying computer photographic image processing in the photo lab industry are known.

For example, when a reproduced image is obtained by photoelectric scanning on the image original by a high-precision scanner such as a layout scanner or a laser color printer, a signal processing unit is provided in the middle of the process to correct the density expression (γ correction) for the input density signal. The following effects are obtained by performing processing such as gradation setting, color correction, and clipping synthesis.

Fading restoration of color film Adjusting highlights and shade gradations, exaggeration of color expression Relief of equipment failure, shooting mistake, development mistake, etc. Expressing creative images, expanding the image area and creating new designs.

When such special processing is executed, the digital signal such as the density signal or the luminance signal of the film original obtained by photoelectrically scanning the film original with a high-precision scanner of a color scanner or a color image tube or a color image pickup plate (for example, CCD) is used. Processing image signals.

Conventionally, this kind of special effect includes mosaic processing arranged regularly, and posterization processing and solarization processing for changing the γ curve into an unrealistic one. However, there is a problem in that it is rare to express a creative image, expand the image area, and create a new design with such processing. Alternatively, for example, DPB 7000 (Quantel), Artron 2
000 (Artronix) Response 300 (Citex), etc. have cutout composition and paint functions, but in this case the creator uses a coordinate pointing device such as a tablet digitizer to draw and add the original image. Not only does it take a considerable amount of time, but it also has the drawback that the sense of the creator is reflected in the reconstructed image.

An example will be described below in which mosaic processing is performed with a total of 25 pixels having a size in the x direction 5 and a size in the y direction 5 as one section. The (m, n) th pixel information of the digital image is a
Expressed as (m, n). Here, the pixel information a (m, n) indicates a digital count value obtained by A / D converting the density signal or the luminance signal of the film original. Then, the pixel information of the original image is a (m,
n) and the pixel information of the reconstructed image after processing is a '(m, n), the following relational expression is obtained in the mosaic processing.

a ′ (5m−i, 5n−j) = a (5m−3,5n−3) where i = 0,1,2,3,4 j = 0,1,2,3,4, m, n is In the relational expression in terms of natural numbers, the central value of the 5 × 5 pixel block is the representative value, and that value is also assigned to the other pixels in the block. However, the representative value is any value if it is the 5 × 5 pixel block. However, the average value may be used.

As described above, the conventional regularly arranged mosaic processing has the following drawbacks, and an improved processing method for expressing the creative image is desired.

The arrangement of rectangular blocks is too regular. Since all pixels in the block have the same value, the information where the original image requires a fine representation (where there are many high frequency components) is lost.

<Purpose> The present invention eliminates the above-mentioned drawbacks of the prior art, provides a new image processing method to the few special effect processing in the related art, expresses a creative image without being influenced by the sense of the creator, and expands the image area. , Which is very useful in creating new designs, and contributes to the design industry, for example, advertising that deals with photographic images, and special photography techniques that are difficult or impossible for the general consumer to do with conventional photography. It is an object of the present invention to provide an image processing method that can be easily incorporated and can contribute to industrial development such as the photographic industry and the photo lab industry.

Particularly, the present invention aims to provide an image processing method for changing a mosaic shape according to input image data.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an example of the flow of a density signal when the present invention is applied to a color scanner. The input signal obtained by photoelectrically scanning the film original loaded in the input drum 1 is converted into a density signal by the logarithmic conversion circuit 2, and then input to the input signal processing unit 4 via the AD converter 3. Each density value is converted according to the type of film, and converted so as to have a fixed relationship with the exposure amount of the film. This is because the film characteristic curve differs depending on the negative film, the positive film, and the reversal film, and in the case of a color image, especially in the negative film, the R, G, and B colors differ. After that, the image is input to the image processing unit 5, which is the heart of the system, and digital image processing is performed. After that, the density signal output from the image processing unit 5 is processed by the output signal processing unit 6 to be converted into a laser light amount control signal, and is output from the light source 9 input to the modulator 8 via the DA converter 7. The laser light is modulated to cause the output drum 10 to reproduce a desired image.

FIG. 2 is a block diagram showing a part of the image processing unit 5 in more detail.

The CPU 11 is a control processor, which has all the real rights of the image processing unit 5, and controls the image processing by the memory of the CPU memory 12. The parameter controller 13 is an arithmetic unit 14, parameter memory 15, parameter setting I / O1
Control 6 and initialize the parameters required for processing,
Set, compare, etc. The processor 18 and the CPU 11 are connected by the image controller 17 and the CPU 11
The processor 18 operates according to the command of. The processor 18 is a core part of the image processing section 5, and is an arbitrary image memory 20-2 selected according to a command of the CPU 11.
6.16 Integrated image memory 27 for bits and IO / 3 for image data
Image data is received from 6 and the calculated result is sent to any selected image memory 20 to 26.16 bit cumulative image memory 27 or image data IO / 36.
In addition, the data can be output to the flag map memory 19, which is a memory dedicated to the carrier, in order to carry the carrier to a necessary address by calculation. Image memory 20 to 2616 Bit accumulation image memory 27 is connected to both CPU BUS and VIDEO BUS, so any image memory 20 to 2 from CPU 11
6.16 It is possible to read from and write to the bit accumulation image memory 27 and to perform real-time calculation between arbitrary memories. Lucupup table at the exit of the image memory
High-speed RAM of 28-34 is connected. This RAM is 256
It has a structure of × 8 bits, 8 RAM address lines (0 to 255 can be specified = 0 to 255 gradations can be specified) are directly connected to the output of each image memory, and 8 data lines are VIDEO BUS. It is connected to the. The contents of RAM can be freely read and written by the CPU 11. Image data I / O35
Is an input / output interface for image, which inputs image data from the input signal processing unit 4 of FIG. 1 and outputs image data to the output signal processing unit 6.

FIG. 3 is a flow chart of a digital image processing method performed by the image processing unit 5, and FIG. 4 is a graph showing the states of the lookup tables 24 to 26, in which the horizontal axis is the input gradation and the vertical axis is the output floor. Shows the key. Fig. 4 (a) shows the standard condition, 0 at address 0, 1 at address 1, 25
The value of 255 is written in the address 5, and the contents of input and output are the same. Also, in FIG. 4 (b), 0
The value 255 is written in the address, the value 254 is written in the address ......, and the value 0 is written in the address 255, indicating that the input-output is an image in which the density data is inverted.

The digital image processing method performed by the image processing unit 5 will be described below in detail with reference to the flow chart of FIG.
Here, the density data of the digital image is shown in the form of ai (m, n) for the sake of explanation. However, i is R, G, and B, and indicates R component image data, G component image data, and B component image data of the original image, respectively. Each pixel is composed of 8 bits for each component, that is, data capable of expressing 256 gradations. The value of the data with the highest density (darkest data) is φ, and the value of the data with the lowest density (the brightest data) is 255
And

Step 1 Explanation of S1 Processor 18 makes image data I / O 28 by the instruction of CPU 11.
The R component image data of the current image is stored in the image memory (1) 20 from the input signal processing unit 4 via. Subsequently, the G component image data and the B component image data of the original image are stored in the image memories (2) (3) 21 and 22, respectively. At this time, the rack up tables (1) to (7) 28 to 34 are shown in FIG. 4 (a).
Is the standard condition.

Description of Step 2 S2 The image data of the image memory (1) 20 is substituted into the image memory (4) 23 by the function of the processor 18. At this time, since the contents of the look-up table (1) 28 are in the standard state as shown in FIG. 4 (a), the contents of the image memory (1) 20 are directly copied to the image memory (4) 23. Similarly, the image data of the image memory (2) 21 and the image memory (3) 22 are copied to the image memory (5) 24 and the image memory (6) 25, respectively.

Step 3 Description of S3 Here, the parameters necessary for the calculation are set. In this embodiment, a parameter indicating the size of the basic pixel block and a parameter indicating the shape of the pixel block are input from a parameter setting I / O 16 using a keyboard (not shown). In the example below, each side of the circumscribed quadrangle of that shape is used as a parameter that represents the size of the basic pixel block.
It is given in the form of m ₀ , n _{0, and} the shape of the pixel block is a random shape. In this description, the shape is irregular, but it may be a fixed shape such as a circle, a triangle, or a quadrangle. Further, in this case, the parameter representing the size of the basic pixel block may be given as a diameter in the case of one side of a circumscribed quadrangle and a circumscribed circle diameter in the case of a polygon. As described above, these parameters are in the form that the creator himself inputs by the parameter setting I / O16. However, if the information is stored in the parameter memory in advance, the operator does not have to input the parameter data. It goes without saying that it can be automated.

Based on the sizes m ₀ , n _{0 of} the basic pixel blocks and the size M × N of the image data set here, the total number P1 of pixel blocks, which is a parameter necessary for the following calculation, is P1 = (M / m _O ). ×
It was calculated by the formula of (N / n _O ) × 2.

Next, the control parameter IP1 used for controlling the following calculation is initialized. Specifically, IP1 = 1 and I
When P1 = 1, target the image memory (1) 20,
When IP1 = 2 and IP1 = 3, the image resolution (2),
(3), 21 and 22 are processed.

Step 4 S4 Description In the following steps, image data to be referred to when determining the size of the pixel block is created and stored in the image memory (7). In this embodiment, the image memory (1)
R component image data of, the G component image data of the image memory (2), and the B component original image data of the image memory (3) are added together at a ratio of R: G: B = 3: 6: 1. The reference image data will be described as the image data close to the above, but it is also possible to use only the G component image data having a high luminosity ratio of R, G, and B as the reference image data. 16 due to the function of processor 18
The bit image memory (8) is reset. Next, the image memory (1) is added to the image memory (8) three times, and the data is added to the image memory (2) and the image memory (3) six times and once, respectively. That is, if the data in the image memories (1), (2), and (3) are ai (m, n) i = R, G, B, and the data in the image memory (8) is represented as Wa (m, n), Wa is (M, n) = 3
× aR (m, n) + 6 × aG (m, n) + aB (m, n). Next, the data in the image memory (8) is divided by 10 and stored in the image memory (7).

That is, the data aT (m, n) in the image memory (7) is aT
(M, n) = (3 × aR (m, n) + 6 × aG (m, n) + aB (m, n)
It becomes / 10.

Step 5 Explanation of B5 IP1 is a control parameter for designating the image memory to be processed. When IPI = 1, the result output is the image memory (1) 20 and the reference image necessary for one operation is the image memory (4 ) 23. Also, when IPI = 2, it is image memory (2) 21 and (5) 24 respectively.
When IPI = 3, the image memories are (3) 22 and (5) 25. Then, when IPI = 4, the calculation in the main image processing unit is ended and the process proceeds to the next sequence.

Explanation of step 6 S6 IP2 = 1, which is the initial setting of control parameters used in the following calculations. This control parameter is step 1
It is counted up in 1 and compared in step 12 with the number of times P1 of calculation of the pixel block which is calculated in step, and is controlled.

Description of Step 7 B7 A random number sequence used in the following processing is set. By setting the random number sequence at this point, the generation of random numbers in the process performed on the image memories (1) to (3) 20 to 22 becomes the same value, and the designated position of the block processing unit is set to 3 image memories. Do the same.

Step 8 S8 Description A basic position for generating a pixel block is calculated by random number generation. Here, between I and M is generated in the x direction, and between 1 and N is generated in the y direction. Here, the basic positions are represented as ms and ns, respectively.

Step 9 Explanation of S9 The four points of the image memory (7) are determined according to the value of ms, ns generated by step 8, A difference d between the maximum value and the minimum value of the data value a _T (i, j) surrounded by is calculated. Due to this difference d, when the value of d is large, the size mb, nb of the pixel block to be actually written is reduced, and when the value of d is small, the size mb, nb of the pixel block to be actually written is increased. To do. In this embodiment, the pixel block mb, nb to be actually written is linearly changed with respect to the difference d between the maximum value and the minimum value as shown in the following equation. It goes without saying that you can do it.

mb = mo-mo * d / 255 nb = no-no * d / 255 (however, it is converted to an integer) Step 10 Explanation of S10 The size m of the pixel block obtained by Step 9
4 points on the image memory (4) by b and nb An arbitrary position in the pixel block surrounded by is written with the value (ms, ns) of the image memory (1) as shown in FIG. This is the case when the control parameter IP2 = 1, and IP2 = 2,3
At that time, the selected value is written from the image memory (2) to the image memory (5) and from the image memory (3) to the image memory (6).

Steps 11, 12 S11, S12 description Step 11 counts up the control parameter IP2, and step 12 branches according to the parameter to obtain IP2.
Is greater than P2, the next step, Step 13, is performed, and when P2 is equal to or less than P2, Step 8 is repeated. That is, steps 8 to 12 are repeated P2 times, and P2 pixel blocks are stored in the image memory (4),
Write in (5) and (6) respectively.

Step 13 Description of S13 Count up of the control parameter IP1 is performed, and then the process proceeds to step 5.

The digital image processing as described above is performed, and the result is that the R, G, and B component image data are stored in the image memory (4) 23, the image memory (5) 24, and the image memory (6) 25, respectively. .

In the previous description, when determining the size of the image block in step 9, the size mb × nb of the pixel block to be actually written is determined by the maximum value and the minimum value in the pixel block of mo × no. The following method is also possible.

It is also possible to make a judgment based on the sum of adjacent pixel elements within the pixel block mo × no.

That is, the image data of the image memory (7) is Labrian or other differential operator to form an image, and the sum S of the values in the range of the pixel block mo × no is taken for the image and the value of the sum S is large. However, the same effect of the present invention can be obtained by making mb, nb small and making mb, nb large with respect to the one having a small sum S.

As described above, according to the present embodiment, it is possible to express different creative images with a higher degree of discreteness as compared with the conventional regular rectangular mosaic processing.

Further, the sizes of pixel blocks (mosaics) do not all have the same value, where the areas with high contrast are small, and the areas with low contrast are large, so mosaic processing that makes the most of the characteristics of the original image information is possible. For example, the out-of-focus area other than the subject of the photograph can be configured with a large mosaic.

In addition, "dark room treatment" that was performed by the conventional silver salt system
In addition to providing new images that were not possible with electronic plate making of or printing systems, the degree of freedom in drawing is increased.

Further, since the image processing process can be unmanned, a specialist is not required, and it can be expected to spread in a laboratory.

In this embodiment, the image processing unit is used as the image processing unit, but it goes without saying that the same effect can be obtained by using a general-purpose computer such as a minicomputer.

In this embodiment, the image is input from the film, but even if the image data is directly captured from the subject from a still video camera, a video camera, etc., the image is recorded via a recording medium such as a magnetic floppy disk, a magnetic tape, an optical disk or a bubble memory. The same effect can be obtained by inputting data.

<Effect> As described above, according to the present invention, it is possible to express a creative image and perform mosaic processing that makes the best use of the characteristics of original image information, as compared with the conventional regular mosaic processing. In particular, the effect of changing the shape of the section according to the contrast of the original image is extremely large.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the flow of a density signal when the present invention is applied to a color scanner, FIG. 2 is a block diagram showing in more detail a part of the image processing section of FIG. 1, and FIG. The flow chart of the embodiment is shown in FIGS. 4 (a) and 4 (b) as the third chart.
FIG. 5 is a diagram showing the state of the lookup table used in the description of the drawings, and FIGS. 5A and 5B are diagrams showing examples of parameter setting. 1 ... Input drum 2 ... Logarithmic conversion circuit 3 ... AD converter 4 ... Input signal processing unit 5 ... Image processing unit 6 ... Output signal processing unit 7 ... DA converter 8 ... Modulator 9 ... … Laser light source 10 …… Output drum 11 …… Control processor 12 …… CPU memory 13 …… Parameter controller 14 …… Calculator 15 …… Parameter memory 16 …… Parameter setting I / O 17 …… Image controller 18… … Processor 19 …… Flag map memory 20-27 …… Image memory 28-35 …… Lookup table 36 …… I / O for image data

(72) Inventor Susumu Matsumura Susumu Shimoge, Takatsu-ku, Kawasaki-shi, Kanagawa 770, Tamagawa Works, Canon Inc. (72) Hiroshi Omura 770 Shimonoge, Takatsu-ku, Kawasaki, Kanagawa Prefecture

Claims (2)

[Claims] 1. In image processing for dividing image data of an original image into a plurality of sections composed of a plurality of pixels, and converting pixel data in each section by the representative value, the section is divided according to the image data of the original image. An image processing method, characterized in that the shape of the image is changed. 2. An image processing method according to claim 1, wherein the shape of the section is changed according to the image contrast of the original image.