JP3825916B2 - Image processing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing method and apparatus for generating a mosaic image by combining a plurality of material images in a mosaic manner.
[0002]
[Prior art]
Mosaic is widely known as “a combination of small pieces of stone, glass, marble, etc. of various colors, which are inlaid on floors and walls and designed, or its technique” (Sanseido Contemporary Japanese Dictionary). Using this technique, it is possible to combine a large number of photographic images into a design or a single photographic image.
[0003]
[Problems to be solved by the invention]
When creating such a mosaic image, tile images called material images are sequentially pasted on the original image. In this case, it is desirable that the original image area and the color of the material image to be pasted are approximated, but it is desirable that the material image contains edge components, or the original image area has edge components and color distribution. In such a case, there is a problem that appropriate color matching cannot be achieved between these regions and the material image, and the quality of the obtained mosaic image is deteriorated.
[0004]
The present invention has been made in view of the above-described conventional example. An area (tile area) obtained by dividing an original image is further divided into a plurality of partial areas, and a material image is also divided into a plurality of partial areas. It is an object of the present invention to provide an image processing method and apparatus for creating a mosaic image using a material image that minimizes the sum of the average density differences between the partial area of the image and the partial area of the material image.
[0005]
An object of the present invention is to provide an image processing method and apparatus capable of generating a mosaic image based on an image while maintaining the color distribution characteristics of the original image.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the image processing apparatus of the present invention comprises the following arrangement. That is,
An image processing apparatus that generates a mosaic image by combining a plurality of material images in a mosaic manner,
An arithmetic unit that divides an original image into a plurality of regions and calculates an average density of each partial region obtained by further dividing the plurality of regions;
A calculation means for dividing each of the plurality of material images into a plurality of material image partial areas and calculating an average density of each of the plurality of material image partial areas;
The material image assigned to the divided region of the original image according to the average density of each partial area calculated by the calculating means and the average density of each of the plurality of material image partial areas obtained by the calculating means. Material image selection means for selecting,
And a mosaic generation means for generating a mosaic image based on the material image selected by the material image selection means,
The computing means calculates an average density for each color in an arbitrary color space of each partial area, and the calculating means calculates an average density for each color in an arbitrary color space of each material image partial area. It is characterized by.
[0007]
In order to achieve the above object, the image processing method of the present invention includes the following steps. That is,
An image processing method for generating a mosaic image by combining a plurality of material images like a mosaic,
A calculation step of dividing an original image into a plurality of regions, and calculating an average density of each partial region obtained by further dividing the plurality of regions;
A calculation step of dividing each of the plurality of material images into a plurality of material image partial regions and calculating an average density of each of the plurality of material image partial regions;
The material image assigned to the divided region of the original image according to the average density of each partial region calculated in the calculation step and the average density of each of the plurality of material image partial regions obtained in the calculation step Material image selection process to select,
And a mosaic generation step of generating a mosaic image based on the material image selected by the material image selection step,
In the calculation step, an average density for each color in an arbitrary color space of each partial area is calculated, and in the calculation step, an average density for each color in an arbitrary color space of each material image partial area is calculated . It is characterized by.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0009]
FIG. 1 is a block diagram showing the configuration of a computer system that executes image processing according to an embodiment of the present invention.
[0010]
In FIG. 1, reference numeral 101 denotes a CPU which controls the entire system in accordance with a program stored in the hard disk 106 and loaded into the RAM 105. A keyboard 102 is used together with the mouse 102a to input various commands and data to the system according to the present embodiment. A display unit 103 includes, for example, a CRT, a liquid crystal, and the like. Reference numeral 104 denotes a ROM, and 105 denotes a RAM, which constitutes a storage unit in the system of the present embodiment and stores programs executed by the system, data used by the system, and the like. Reference numeral 106 denotes a hard disk and 107 denotes a floppy disk device, which constitutes an external storage device used in the file system of the system according to the present embodiment. Reference numeral 108 denotes a printer.
[0011]
The hard disk 106 stores a plurality (P) of tile images that are constituent elements of a mosaic image. According to a program described later, M × N images selected from the tile images are stored as shown in FIG. A mosaic image is created by combining M sheets in the horizontal direction and N sheets in the vertical direction. The mosaic image thus created is stored as an image file on the hard disk 106 and displayed on the CRT 103 or output to the printer 108 for printing.
[0012]
FIG. 3 is a diagram for explaining the relationship between a plurality of types of images used in the mosaic method.
[0013]
In FIG. 3, an image 201 indicates a design or image that is a base when an image is constructed using the mosaic technique. The image 202 is a mosaic image configured using a plurality of small images (tiles) by a mosaic method. A material image 203 is a material image used to construct the image 202. The number P of these material images is a sufficiently large number so that the types of colors and textures that are generally required for constructing the image 202 can be prepared. Here, for the sake of explanation, the size of each of the P material images is the same as the size of the tile, but the size of each material image does not necessarily match the size of the tile, and all the P images are the same. They do not have to be the same size. Thus, when the size of each material image is different, it is necessary to convert the size of the material image when pasting on the corresponding tile of the image 202. Here, the number P is sufficiently larger than the above-mentioned M × N sheets.
[0014]
Next, a method for selecting an appropriate M × N images from the P material images 203 and creating the mosaic image 202 from the original image 201 will be described with reference to the flowchart of FIG.
[0015]
FIG. 4 is a flowchart showing a mosaic image creation process executed in the computer system according to the present embodiment. A program for executing this process is stored in, for example, the hard disk 106 and loaded into the RAM 105 for execution.
[0016]
First, in step S31, the original image 201 is divided into M × N areas (tile areas). As a result, as shown in FIG. 5, M × N rectangular regions TL (0, 0), TL (1, 0), TL (2, 0), TL (3, 0),. −1, N−1) is generated.
[0017]
In FIG. 5, X and Y are the numbers of pixels in the horizontal and vertical directions of the image 201, respectively. P and q are the number of pixels in the horizontal and vertical directions of each area when the image 201 is divided into M × N rectangular areas TL (0, 0),..., TL (M−1, N−1). is there. Therefore, the relationships X = p × M and Y = q × N are established. FIG. 5 shows a case where M = 4 and N = 5.
[0018]
FIG. 6 shows the color configuration of the individual areas into which the image 201 is thus divided, and each area is composed of p × q three primary colors, red (R), green (G), and blue (B) pixels. It is configured.
[0019]
In step S32, the M × N areas are further divided into α × β, and in step S33, the average density of each of the divided partial areas is calculated.
[0020]
FIG. 7 is a diagram for explaining how each region is further divided. Here, each region has a size of p × q pixels as described above, but it is equally divided into α × β regions. . FIG. 7 illustrates a case where α = 3 and β = 2. If the size of the partial area thus divided is v × ω pixels, in general,
v × α = p
ω × β = q
The relationship holds.
[0021]
Here, for each of I and J satisfying 0 ≦ I ≦ α−1 and 0 ≦ J ≦ β−1.
[Expression 1]
[0023]
RI, J = ΣRi / (v × w) (average R concentration in partial region (I, J))
GI, J = ΣGi / (v × w) (average G concentration in partial region (I, J))
BI, J = ΣBi / (v × w) (average B concentration in partial area (I, J))
Thus, the average density for each partial region is calculated. Here, ΣRi is the total sum of the R components of the pixels included in the partial area, and the same applies to the other color components.
[0024]
For example, R1,0 represents the R average density of the partial region 700 indicated by oblique lines in the region shown in FIG.
[0025]
In step S34, each of the P material images is equally divided into α × β pieces similarly to the image 201. In step S35, the R, G, B average densities of the partial areas thus divided are calculated. Assuming that the size of each material image is p ′ × q ′ pixels, it is equally divided into α × β and divided into v ′ × ω ′ pixel areas. This
v ′ × α = p ′
ω ′ × β = q ′
The relationship holds. Similarly, for I and J where 0 ≦ I ≦ α−1 and 0 ≦ J ≦ β−1, the relationship of the following Equation 2 is established as in Equation 1 described above.
[Expression 2]
[0027]
R′I, J = ΣRi / (v ′ × w ′)
G′I, J = ΣGi / (v ′ × w ′)
B′I, J = ΣBi / (v ′ × w ′)
In step S 36, counters Xpos (0 ≦ Xpos ≦ M−1) and Ypos (0 ≦ Ypos ≦ N−1) indicating the position of the region of the image 201 to be processed are both initialized to “0”. . Here, (Xpos, Ypos) = (0, 0) indicates the coordinate position of the region TL (0, 0) of the original image 201.
[0028]
In step S37, the material image most suitable for the area indicated by the position counters Xpos and Ypos is selected from the P material images.
[0029]
Here, the distance ΔE of the average density of each region and the material image is defined as follows.
[0030]
[Equation 3]
[0031]
ΔE = ΣΣ {(R′I, J−RI, J) squared + (G′I, J−GI, J) squared + (B′I, J−BI, J) squared}
Here, the first “Σ” of “ΣΣ” means the sum from I = 0 to I = (α−1), and the second “Σ” is from J = 0 to J = (β−1). It means the sum of up to.
[0032]
That is, here, the average density (R′I, J, G′I, J, B′I, J) of each color of each partial area into which the material image is divided and each part of each area into which the image 201 is divided. The sum of squares of the difference from the average density (RI, J, GI, J, BI, J) for each color of the area is obtained, and the material image that minimizes the value of ΔE is determined as the optimum material for the area. Select as an image.
[0033]
Here, when α = β = 1, the color difference and luminance distribution information in each area of the image 201 is lost, so there is no problem in the area where the color distribution is flat. If the image includes an edge, an optimal material image may not be selected.
[0034]
On the other hand, if α> 1, β> 1 (α and β are both positive integers), it is possible to achieve alignment with the material image reflecting the color distribution in each region of the image 201, and an appropriate material image. Can be selected. As a result, the quality of the mosaic image thus generated can be improved.
[0035]
In this process, in step S38, the position counter Xpos is incremented by 1 to refer to the next area, and when the value of the position counter Xpos becomes equal to or larger than the right end (“3” in the example of FIG. 5), the position counter Ypos is incremented by 1. Xpos is set to “0”, and steps S36 to S39 are repeatedly executed until the above-described processing is completed for all regions (tile regions) of the image 201 in step S39.
[0036]
It should be noted that the operations of Equation 1 and Equation 2 described above may be executed by software as described above, or may be executed by dedicated hardware.
[Other embodiments]
The division into partial areas is not limited to the above-described rectangular shape, and may be divided into non-rectangular areas as shown in FIG. 8, for example.
[0037]
In the above-described embodiment, the average density is calculated using the RGB values of the pixels. However, other than this, for example, the average density may be obtained based on pixel data defined in a color space such as Yuv or Lab.
[0038]
Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), or a device (for example, a copier, a facsimile device, etc.) including a single device. You may apply to.
[0039]
In addition, an object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus stores the storage medium. This can also be achieved by reading and executing the program code stored in.
[0040]
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
[0041]
As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0042]
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on the instruction of the program code. A case where part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included.
[0043]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. This includes a case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0044]
As described above, according to the present embodiment, appropriate matching between a material image and a tile can be achieved, and the quality of a mosaic image can be improved.
[0045]
【The invention's effect】
As described above, according to the present invention, a region (tile region) obtained by dividing the original image is further divided into a plurality of partial regions, and the material image is also divided into a plurality of partial regions, so that a partial region of the original image is obtained. Since the mosaic image is created using the material image that minimizes the total number of average density differences between the image and the partial area of the material image, it is possible to create a mosaic image that makes use of the color distribution or color change of the original region.
[0046]
Further, according to the present invention, a mosaic image based on the original image can be generated while maintaining the color characteristics of the original image.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a computer system according to an embodiment.
FIG. 2 is a diagram illustrating a mosaic image.
FIG. 3 is a diagram illustrating a process of generating a mosaic image.
FIG. 4 is a flowchart illustrating a flow of mosaic image creation processing in the computer system according to the present embodiment.
FIG. 5 is a diagram illustrating an example of a mosaic image.
FIG. 6 is a diagram for explaining a color configuration of individual tiles constituting a mosaic image.
FIG. 7 is a diagram illustrating an example of dividing a material image.
FIG. 8 is a diagram illustrating another example of dividing a material image.
[Explanation of symbols]
101 CPU
102 Keyboard 102a Mouse 103 Display unit 104 ROM
105 RAM
106 Hard disk 107 Floppy disk 108 Printer

Claims (12)

An image processing apparatus that generates a mosaic image by combining a plurality of material images in a mosaic manner,
An arithmetic unit that divides an original image into a plurality of regions and calculates an average density of each partial region obtained by further dividing the plurality of regions;
A calculation means for dividing each of the plurality of material images into a plurality of material image partial areas and calculating an average density of each of the plurality of material image partial areas;
The material image assigned to the divided region of the original image according to the average density of each partial area calculated by the calculating means and the average density of each of the plurality of material image partial areas obtained by the calculating means. Material image selection means for selecting,
And a mosaic generation means for generating a mosaic image based on the material image selected by the material image selection means,
The computing means calculates an average density for each color in an arbitrary color space of each partial area, and the calculating means calculates an average density for each color in an arbitrary color space of each material image partial area. An image processing apparatus.   The image processing apparatus according to claim 1, wherein the number of partial regions obtained by further dividing the plurality of regions is equal to the number of material image partial regions obtained by dividing the material image. The material image selection means selects a material image in which the difference between the average density of each color of the partial image area of the area having the original image and the average density of each color of the material image partial area of the material image is minimized. the image processing apparatus according to claim 1 or 2, characterized in that selected as material image to be allocated to.   The material image selecting means is a material having a minimum value obtained by summing a square of a difference between an average density of each color of a partial image area of an area having the original image and an average density of each color of the material image partial area of the material image. The image processing apparatus according to claim 1, wherein an image is selected. An image processing method for generating a mosaic image by combining a plurality of material images like a mosaic,
A calculation step of dividing an original image into a plurality of regions, and calculating an average density of each partial region obtained by further dividing the plurality of regions;
A calculation step of dividing each of the plurality of material images into a plurality of material image partial regions and calculating an average density of each of the plurality of material image partial regions;
The material image assigned to the divided region of the original image according to the average density of each partial region calculated in the calculation step and the average density of each of the plurality of material image partial regions obtained in the calculation step Material image selection process to select,
And a mosaic generation step of generating a mosaic image based on the material image selected by the material image selection step,
In the calculation step, an average density for each color in an arbitrary color space of each partial area is calculated, and in the calculation step, an average density for each color in an arbitrary color space of each material image partial area is calculated . An image processing method characterized by the above. 6. The image processing method according to claim 5 , wherein the number of each partial area obtained by further dividing the plurality of areas is equal to the number of the material image partial areas obtained by dividing the material image. In the material image selection step, a material image that minimizes the difference between the average density of each color of the partial image area of the area having the original image and the average density of each color of the material image partial area of the material image The image processing method according to claim 5, wherein the image processing method is selected as a material image to be assigned to an image. In the material image selection step, the material having the smallest value obtained by summing the squares of the difference between the average density of each color of the partial image region of the region having the original image and the average density of each color of the material image partial region of the material image 6. The image processing method according to claim 5 , wherein an image is selected. A computer-readable storage medium storing a program for executing an image processing method for generating a mosaic image by combining a plurality of material images in a mosaic manner,
An arithmetic process module that divides an original image into a plurality of regions and calculates an average density of each partial region obtained by further dividing the plurality of regions;
A calculation process module that divides each of the plurality of material images into a plurality of material image partial regions and calculates an average density of each of the plurality of material image partial regions;
According to the average density of each partial area calculated by the calculation process module and the average density of each of the plurality of material image partial areas obtained by the calculation process module, the original image is assigned to a divided area. A material image selection process module for selecting a material image;
And a mosaic forming process module to create a mosaic image based on the material image selected by the material image selection process module,
The calculation process module calculates an average density for each color in an arbitrary color space of each partial area, and the calculation process module calculates an average density for each color in an arbitrary color space of each material image partial area. A storage medium characterized by: 10. The storage medium according to claim 9 , wherein the number of each partial area obtained by further dividing the plurality of areas is equal to the number of the material image partial areas obtained by dividing the material image. In the material image selection process module, the material image that minimizes the difference between the average density of each color of the partial image area of the region having the original image and the average density of each color of the material image partial area of the material image The storage medium according to claim 9 or 10 , wherein the storage medium is selected as a material image to be assigned to an area. In the material image selection process module, a value obtained by summing a square of a difference between an average density of each color of a partial image area of the region having the original image and an average density of each color of the material image partial area of the material image is the smallest. The storage medium according to claim 9 , wherein a material image is selected.

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