JPH0950514A - Processing method and device for converting picture element density - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the high quality of a picture and to speed up processing time. SOLUTION: Picture element density conversion for an inputted original picture is executed by a high speed projection method at 1st conversion magnification (p1 , q1 ) (S4) and its converted result is outputted as an intermediate picture (S5). Then picture element density conversion for the intermediate picture is executed by a nearest neighbor method at 2nd conversion magnification (p2 , q2 ) (S6) and the converted result is outputted as an object picture (S7). The 1st and 2nd conversion magnification values (p1 , q1 ), (p2 , q2 ) are set up by distributing the conversion magnification (p, q) of the object picture to the original picture at respective required rates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an area density conversion processing method and apparatus for enlarging / reducing an image when editing a document including a chart or the like.

[0002]

2. Description of the Related Art In recent years, an information processing apparatus having a document processing function for processing a document including not only a character string but also a chart or the like has been developed. Such an information processing device is
It has editing functions such as operation of characters given as image data and layout of figures and tables. At this time, a process of re-sampling the original image at a new sampling interval, that is, a surface element density conversion process of enlarging or reducing the original image is required.

As a pixel density conversion processing method for a digital image, there are a nearest neighbor method, a logical sum method, a projection method and the like. A general description of these pixel density conversion processes will be given with reference to FIG.

Pixels of the original image (hereinafter abbreviated as original pixels)
Are arranged at intervals of x _{0 in} the x direction and y _{0 in} the y direction.
When the pixel density conversion processing is performed on the original image in the x direction and the y direction at the conversion magnifications p ′ and q ′, a converted image is obtained. When the converted image is projected onto the original image, the pixel intervals of the converted image are x ₀ / p 'and y ₀ / q', respectively, and the arrangement is as shown in the figure, for example. Focusing on one of the pixels in the figure, a method of pixel density conversion processing will be described. For example, a pixel of a converted image (hereinafter, abbreviated as a converted pixel) R ′
Is the density of I _{R ′} and the four original pixels A ′ and B ′ in the vicinity of the converted pixel R ′
・ The concentrations of C '・ D' are I _{A '} , I _B' , I _{C '} , I _D'
And

The nearest neighbor method is a method in which one original pixel located closest to the conversion pixel R'is obtained and the density value thereof is used as the density value of the conversion pixel R '. In the above example, since the original pixel D ′ is closest to the converted pixel R ′, I _{R ′} = I _{D ′} .
However, although the nearest neighbor method is simple in processing, since only one original pixel is referred to, when a character having a narrow line width is reduced, the probability of referring to an original pixel having a density value of 0 becomes high.
Therefore, for example, when the kanji "I" is reduced,
As shown in (a), a phenomenon called so-called "blank", in which strokes are interrupted, tends to occur.

In the logical sum method, the density of the converted pixel R'is determined by the logical sum of the four original pixels A ', B', C ', D'in the vicinity. However, in the logical sum method, the four original pixels A ′, B ′, C ′ in the vicinity are
If at least one pixel of D'has a density value of 1, the converted pixel R'has a density value of 1, so FIG.
As shown in, the line becomes thick, and the phenomenon of so-called "grip" in which strokes are connected is likely to occur.

[0007] Projection is the average concentration of the original pixels projected _'the converted pixel R' concentration I _R in. That is, the concentration I _{A ′} · I
The average concentration of _{B ′} · IC _′ · _{ID ′} is the concentration IR _′ . Therefore,
The projection method has few "blurring" and "blurring" in the converted image, and the correlation with the original image is well preserved. However, the projection method has a drawback that the processing time is long because it requires a large amount of calculation. In order to solve this, there is a high-speed projection method in which the calculation amount of the projection method is reduced and the speed is significantly increased. The high-speed projection method can obtain a converted image with less conversion distortion and higher quality than the method such as the nearest neighbor method.

[0008]

However, the high-speed projection method is capable of high-quality pixel density conversion, but it requires a long processing time especially when the number of pixels of the converted image is large at the time of enlargement conversion. I have a problem. In other words, considering the case of implementing the high-speed projection method with software,
When the pixel density conversion of the digital image is performed by software, it is necessary to repeat the calculation of the density value of each pixel of the converted image for all the pixels, and thus the processing time becomes long. The high-speed projection method requires 5 multiplications per pixel and is not suitable for real-time processing by software.

The present invention has been made in view of the above conventional problems, and an object thereof is to perform high-quality and high-speed processing by performing two-step surface element density conversion by a high-speed projection method and a nearest neighbor method. It is an object of the present invention to provide a surface element density conversion processing method and apparatus capable of performing the above image processing.

[0010]

In order to achieve the above object, the surface element density conversion processing method according to claim 1 of the present invention is an area conversion method for converting an original image, which is a digital image, at a desired conversion magnification. In the surface element density conversion processing method in which the desired target image is obtained by performing the processing, the surface element density conversion processing includes processing for once converting an original image into an intermediate image by a high-speed projection method and the intermediate image by a nearest neighbor method. From the target image to the target image is divided into two stages of conversion process,
However, the high-speed projection method calculates the density value of the converted pixel from the average density of the pixels of the original image projected on the converted pixel, and the nearest neighbor method among the pixels of the original image projected on the converted pixel, It is characterized in that the density value of the pixel of one original image at the closest position is used as the density value of the converted pixel.

According to the above method, the high-speed projection method calculates the density value of the converted pixel from the average density of the pixels of the original image projected on the converted pixel. On the other hand, since the nearest neighbor method uses the density value of the pixel of one original image closest to the converted pixel as the density value of the converted pixel, the time required for conversion is short.

According to the present application, when the original image is subjected to enlargement / reduction conversion processing, that is, surface element density conversion processing to obtain a target image, two-step conversion processing by the high-speed projection method and the nearest neighbor method is performed. It is possible to perform the surface element density conversion processing that makes the most of the advantage of. That is, a high-quality target image that is more faithful to the original image can be formed by the high-speed projection method, and the processing time can be shortened by the nearest neighbor method.

As a result, the processing time can be shortened as compared with the conventional one in which the surface element density conversion processing is performed only by the high speed projection method. Further, the image quality can be improved as compared with the conventional one in which the surface element density conversion processing is performed only by the nearest neighbor method.

The surface element density conversion processing method according to claim 2 is
It is characterized in that the surface element density conversion processing is expansion conversion processing.

According to the above method, since the surface element density conversion processing is the expansion conversion processing, if the high speed projection method is used, the amount of calculation becomes very large and the processing time becomes particularly long. Therefore, by performing a two-step enlargement conversion process using the high-speed projection method and the nearest neighbor method, a significant speedup can be realized as compared with the enlargement conversion using only the high-speed projection method.

A surface element density conversion processing device according to claim 3 is
A conversion factor input unit for inputting the desired conversion factor in a surface element density conversion processing device that obtains a desired target image by performing a surface element density conversion process on an original image that is a digital image at a desired conversion ratio, An intermediate image generation unit that performs surface element density conversion by the projection method and creates an intermediate image from the original image according to the first conversion magnification, and a surface element density conversion by the nearest neighbor method, and converts the intermediate image from the target image according to the second conversion magnification. And a magnification calculation unit that calculates the first conversion magnification and the second conversion magnification by allocating the desired conversion magnification (for example, a high-speed projection method magnification calculation section and a nearest neighbor method magnification calculation section). It is characterized by having and.

According to the above configuration, first, when a desired conversion ratio is input from the conversion ratio input unit, the ratio calculation unit allocates the conversion ratio at a predetermined ratio, and the first conversion ratio and the second conversion ratio.
Calculate the conversion factor. Thereafter, the intermediate image generation unit performs surface element density conversion by the high-speed projection method, creates an intermediate image from the original image according to the first conversion magnification, and the target image generation unit performs surface element density conversion by the nearest neighbor method, A target image is created from the intermediate image according to the second conversion magnification.

As a result, the surface element density conversion processing method using the two-step conversion processing by the high speed projection method and the nearest neighbor method according to the first aspect can be easily achieved. As a result,
The high-speed projection method can form a high-quality target image that is more faithful to the original image, and the nearest neighbor method can reduce the processing time.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The surface element density conversion processing device according to the present embodiment is used for an information processing device that edits a document.

The above information processing apparatus, as shown in FIG.
An image input device 1, a frame memory 2, a surface element density conversion processing device, and a display device 3 are provided.

The image input from the image input device 1 is stored in the frame memory 2. The original image stored in the frame memory 2 is input to a surface element density conversion processing device, where the surface element density conversion is performed and a target image is created. The target image is displayed on the display device 3.

The above-mentioned surface element density conversion processing device includes a conversion magnification input unit 4, a high speed projection method magnification calculation unit 5, a nearest neighbor method magnification calculation unit 6, an intermediate image generation unit 7, a target image generation unit 8, and an intermediate image buffer 9. , And the converted image buffer 10.

The conversion magnification input section 4 inputs the conversion magnification from the original image to the target image. The high-speed projection method magnification calculation unit 5
Based on the conversion magnification, the first conversion magnification when converting the original image into the intermediate image by the high speed projection method is calculated. The nearest neighbor method magnification calculation unit 6 also calculates a second conversion magnification when the intermediate image is converted into a target image by the nearest neighbor method based on the conversion magnification. The intermediate image generation unit 7 converts the original image into a surface element density by a high speed projection method to create an intermediate image. The intermediate image buffer 9 temporarily stores the intermediate image generated by the intermediate image generation unit 7. Then, after the intermediate image stored in the intermediate image buffer 9 is read, the target image generation unit 8 creates a target image by performing surface element density conversion on the intermediate image by the nearest neighbor method. The converted image buffer 10 temporarily stores the target image generated by the target image generation unit 8. The stored target image is read out and displayed on the display device.

The operation of the surface element density conversion processing device having the above configuration will be described with reference to FIG. The original image is assumed to be input by the image input device 1.

First, the conversion magnification input unit 4 inputs the conversion magnification (p, q) of the target image with respect to the original image (S).
1). Here, p is the horizontal (horizontal) conversion magnification from the original image to the target image, and q is the vertical (vertical) direction.
Is the conversion ratio of. Next, in the high-speed projection method magnification calculation unit 5 and the nearest neighbor method magnification calculation unit 6, the conversion magnification (p, q) is converted into the first conversion magnification (p ₁ , q ₁ ) of the high-speed projection method and the nearest neighbor method. It is allocated to the second conversion magnification (p ₂ , q ₂ ) (S2). However, p = p ₁ · p ₂ and q = q ₁ · q ₂ are satisfied.

When the original image is input to the surface element density conversion processing device (S3), the intermediate image generation unit 7 performs surface element density conversion by the high speed projection method in accordance with the first conversion magnification (p ₁ , q ₁ ). (S4), an intermediate image is created (S5). The intermediate image once stored in the intermediate image buffer 9 is input to the target image generation unit 8 and the second conversion magnification (p ₂ , q ₂ )
Then, the surface element density conversion by the nearest neighbor method is performed (S
6) The final target image is created (S7).

That is, in this embodiment, the process of creating the target image by performing the surface element density conversion on the original image is performed more recently after the intermediate image obtained by converting the original image by the high-speed projection method is created. This is performed by a two-step process in which an intermediate image is converted by a side method to create a target image.

Next, a specific method of setting the first conversion magnification (p ₁ , q ₁ ) and the second conversion magnification (p ₂ , q ₂ ) will be described.

When the second conversion magnification (p ₂ , q ₂ ) from the intermediate image to the target image by the nearest neighbor method is large, that is, when it is greatly enlarged, the image quality is improved as compared with the enlargement by only the high speed projection method. Degradation is expected. Therefore, the second conversion magnification (p
The value of ( ₂ , q ₂ ) must be limited to a value that does not deteriorate the image quality. The evaluation of the image quality deterioration is performed by enlarging and converting the intermediate image created by smoothing the contour of the character by the high speed projection method by the nearest neighbor method. This is because the high-speed projection method is capable of enlarging conversion and simultaneously smoothing the contour, while the nearest neighbor method causes rattling of the contour.

An example of image quality evaluation is shown in FIG. p = q = 16.0
At that time, four cases of p ₂ = q ₂ = 1.0, 2.0, 4.0 and 8.0 were evaluated. (A) shows the enlargement ratio by the nearest neighbor method of 1.0, which is actually the enlargement result only by the high-speed projection method. (A) and the magnification of the nearest neighbor method is 2.0
Even when compared with double (b) or enlargement magnification 4.0 (c), the rattling of the contour of the target image is not very noticeable. However, the magnification ratio of the nearest neighbor method is 8.
When it becomes as large as 0 times, the rattling of the contour becomes noticeable.

As described above, when the enlargement factor of the nearest neighbor method becomes large, the deterioration of the image quality becomes a problem. From this result, the maximum limit values of the second conversion magnification (p ₂ , q ₂ ) are both set to 4.0.

The first conversion magnification (p ₁ , q ₁ ) and the second conversion magnification (p ₂ , q ₂ ) are specifically obtained by using the maximum limit value. However, the horizontal width W _S and vertical width H _{S of} the original image, the horizontal width W _I and vertical width H _{I of} the intermediate image, and the horizontal width W _O and vertical width H _{O of} the target image (see FIG. 5). Further, the maximum width W _IM and maximum height H _IM when the intermediate image is the largest, and the maximum width W _OM and maximum height H _OM when the target image is the largest.

The maximum width W _IM and maximum height H _IM satisfy the relationship of W _IM = W _OM / 4 H _IM = H _OM / 4. Therefore, the first and second conversion magnifications p ₁ and p ₂ are p ₁ = W _IM / W _S p ₂ = W _O / W _IM when the width W _O of the target image is larger than the maximum width W _IM. Become. On the other hand, when the width W _O is smaller than the maximum width W _IM , the conversion magnification p ₂ is a relatively small value, that is, 1.0 <p ₂
Set to 4.0. In this embodiment, for example, p ₂ = 2.0 is fixed. Then, the width W _I of the intermediate image is W _I = W _O /
since it is determined by p ₂ = W _O / _2, it becomes _{p 1 = W I / W S} p 2 = 2. The first and second conversion magnifications q ₁ and q ₂ can be similarly obtained.

A specific example of the case where the first and second conversion magnifications are determined based on the above setting method and the surface element density conversion processing is performed will be described below. W _O <W _IM , H _O <H _IM , p = W _O /
When W _S = 3.0 and q = H _O / H _S = 3.0, p ₁ = q ₁
= 1.5 and p ₂ = q ₂ = 2.0.

First, the original image is converted into an intermediate image by the high-speed projection method at the first conversion magnification of 1.5 times. When the intermediate image is projected on the original image, the arrangement of the original pixels and the converted pixels is as shown in FIG. 4, for example. Note that a pixel represents a center point of an image element, a pixel of an original image is called an original pixel, and a pixel of an intermediate image (or a target image) is called a conversion pixel. A method of obtaining the density value of this converted pixel will be described.

In the high-speed projection method, when the converted pixel is projected on the original image, which divided area among the divided areas surrounded by the four original pixels has the converted pixel is first obtained, and the converted pixel is converted according to the area. Obtain the density value of the pixel. The divided area is an area that defines a logical expression for calculating the density value in the high speed projection method.

As shown in FIG. 4, paying attention to converted pixel R _1, 4 original pixels near the converted pixel R ₁ is the original pixel A, B,
D and E. The rectangular area surrounded by the four original pixels is divided into eight divided regions G ₁ ~G _8.

The density value of the converted pixel in each divided area is obtained using the density values of the four original pixels in the vicinity. That is, the densities I _{G1 to} I _G8 of the converted pixels in the divided areas G _{1 to} G ₈ are as follows using the densities I _A , I _B , I _D , and I _E of the original pixels A, B, D, and E. You can ask. That is, for example, if the density value of the original pixels A and B is 1 (black circle in the figure) and the density value of the original pixels D and E is 0 (white circle in the figure), I _G1 = I _A = 1 I _G2 = I _{D = 0 I G3 = I E =} 0 I G4 = I B = 1 I G5 = I A ∧ (I B ∨I D ∨I E) ∨ (I B ∧I D ∧I E) = 1∧ (1∨0 ∨0) ∨ (1∧0∧0) = 1 I _G6 = I _D ∧ (I _A ∨I _B ∨I _E ) ∨ (I _A ∧I _B ∧I _E ) = 0 ∧ (1 ∨1∨0) ∨ (1∧1∧0) = 0 I _G7 = I _E ∧ (I _A ∨I _B ∨I _D ) ∨ (I _A ∧I _B ∧I _D ) = 0 ∧ (1 ∨1∨0) ∨ (1 _{∧1∧0) = 0 I G8 = I} B ∧ (I A ∨I D ∨I E) ∨ (I A ∧I D ∧I E) = 1∧ (1∨0∨0) ∨ (1∧0∧ 0) = 1. However, ∧ is a logical product and ∨ is a logical sum.

At this time, since the conversion pixel R ₁ is on the boundary line of the divided areas G ₅ , G ₆ , G ₇ , and G ₈ , the density I
_R1 is the logical sum of the concentrations I _G5 , I _G6 , I _G7 , and I _G8 of these four regions, and is obtained by the following formula.

I _R1 = I _G5 ∨ I _G6 ∨ I _G7 ∨ I _G8 = 1 ∨0 ∨0 ∨1 = 1 Therefore, in this example, the density value of the conversion pixel R ₁ is 1.

Next, focusing on the converted pixel R ₂ , the four neighboring pixels are the original pixels E, F, H, and I. Conversion pixel R ₂
, Of the divided regions G ₁₁ ~G ₁₈ surrounded by four pixels, since on the divided region G _11, the concentration I _R2 becomes I _R2 = I _E = 0.

Subsequently, the intermediate image is converted into the target image by the nearest neighbor method with the second conversion magnification of 2.0 times.

In the nearest neighbor method, when the target image is projected on the intermediate image, the value 1 is the closest to the converted pixel of the target image.
The original pixel (in this case, which corresponds to the converted pixel of the intermediate image converted by the high-speed projection method) is obtained, and the density value thereof is set as the density value of the converted pixel. That is, for example, if the original pixel located closest to the converted pixel has a density value of 1, the converted pixel also has a density value of 1.

As described above, according to the surface element density conversion processing method of the present embodiment, the surface element density conversion processing is performed separately in the two-step conversion processing of the high speed projection method and the nearest neighbor method. .
At this time, the original image is converted by the high-speed projection method to create an intermediate image, with about 1/4 to 1/2 of the target conversion magnification as the first conversion magnification. Subsequently, the intermediate image is converted into the target image by using the nearest neighbor method based on the second conversion magnification such that the product of the first conversion magnification and the second conversion magnification becomes the target conversion magnification. This method is particularly effective when the size of the target image is too large to be processed by the high speed projection method during the enlargement conversion.

As a result, the nearest neighbor method can obtain a processing speed which is about 5 to 10 times that of the high speed projection method. Therefore, the two-step processing of the high speed projection method and the nearest neighbor method of the present embodiment enables Significant speed-up can be realized compared with enlargement conversion using only the high-speed projection method. On the other hand, by partially using the nearest neighbor method, it is expected that the image quality will deteriorate as compared with the enlargement conversion only by the high-speed projection method, but if the enlargement magnification from the intermediate image to the final target image is not too large, There is almost no difference in image quality.

As a result, a high-quality target image more faithful to the original image can be formed by the high-speed projection method, and
The processing time can be shortened by the nearest neighbor method. Therefore, the processing time can be shortened as compared with the conventional one in which the surface element density conversion processing is performed only by the high-speed projection method.
Further, the image quality can be improved more than the conventional one in which the area density conversion processing is performed only by the nearest neighbor method and the "blurring" phenomenon or the like occurs.

The surface element density conversion processing apparatus of this embodiment can be applied to reduction conversion. However, in this case, the processing time of the high-speed projection method does not depend on the size of the original image. Therefore, the processing time when the reduction conversion is performed only by the high-speed projection method is shorter than the processing time of the two-step processing of the present embodiment. It becomes shorter by the creation time of the intermediate image.

[0048]

As described above, in the surface element density conversion processing method according to the first aspect of the present invention, the surface element density conversion processing includes a processing of once converting an original image into an intermediate image by a high speed projection method,
The intermediate image is converted into a target image by the nearest neighbor method, and is divided into two stages of conversion processing. However, the high-speed projection method uses the average density of the pixels of the original image projected on the converted pixels. The density value of the converted pixel is calculated, and in the nearest neighbor method, the density value of the pixel of one original image closest to the pixel of the original image projected on the converted pixel is set as the density value of the converted pixel. It is a composition.

As a result, when the original image is set as a desired target image, a two-step surface element density conversion process by the high-speed projection method and the nearest neighbor method is performed. It is possible to form a target image of high quality and to shorten the processing time by the nearest neighbor method.

The surface element density conversion processing method according to claim 2 is
This is a configuration in which the area density conversion processing is expansion conversion processing.

As a result, the processing time becomes particularly long when the enlargement conversion processing is performed only by the high-speed projection method. Therefore, by performing the two-step enlargement conversion processing by the high-speed projection method and the nearest neighbor method, a significant speedup is achieved. Has an effect that can be realized.

The surface element density conversion processing device according to claim 3 is
A conversion magnification input unit that inputs a desired conversion magnification, an intermediate image generation unit that performs surface element density conversion by the high-speed projection method, and creates an intermediate image from the original image according to the first conversion magnification, and a surface element density that is the nearest neighbor method. A target image generation unit that performs conversion and creates a target image from the intermediate image according to the second conversion magnification, and a magnification calculation unit that calculates the first conversion magnification and the second conversion magnification by allocating the desired conversion magnification It is a composition.

As a result, the surface element density conversion processing method using the two-step conversion processing by the high speed projection method and the nearest neighbor method according to the first aspect can be easily achieved. As a result,
The high-speed projection method has the effect of being able to form a high-quality target image that is more faithful to the original image and the processing time can be shortened by the nearest neighbor method.

[Brief description of drawings]

FIG. 1 is a block diagram showing a surface element density conversion processing operation in a surface element density conversion processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of the surface element density conversion processing device.

FIG. 3 is an explanatory diagram showing a display example of a target image when the conversion magnification by the high speed projection method and the conversion magnification by the nearest neighbor method are changed.

FIG. 4 is a schematic diagram showing an arrangement of original pixels and converted pixels when an original image is converted into an intermediate image by surface element density conversion by a high-speed projection method.

FIG. 5 is an explanatory diagram showing a horizontal width and a vertical width of an original image, an intermediate image, and a target image.

FIG. 6 is a schematic diagram showing an arrangement of original pixels and converted pixels when an original image is converted into a target image by surface element density conversion by a conventional nearest neighbor method.

7A is an explanatory diagram showing a display example of a target image after reduction conversion by the nearest neighbor method, and FIG. 7B shows a display example of a target image after reduction conversion by the logical sum method. FIG.

[Explanation of symbols]

4 conversion magnification input unit 5 high-speed projection method magnification calculation unit (magnification calculation unit) 6 nearest neighbor method magnification calculation unit (magnification calculation unit) 7 intermediate image generation unit 8 target image generation unit R ₁ / R ₂ conversion pixel

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshihiro Kitamura 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Naofumi Saika 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside the company

Claims (3)

[Claims] 1. A surface element density conversion processing method in which an original image, which is a digital image, is subjected to a surface element density conversion processing at a desired conversion magnification to obtain a desired target image, wherein the surface element density conversion processing is high-speed projection. Method is used to convert the original image into an intermediate image once, and the nearest neighbor method to convert the intermediate image into a target image. The density value of the converted pixel is calculated from the average density of the pixels of the original image projected on the converted pixel, and the nearest neighbor method is one of the pixels of the original image projected on the converted pixel, which is the closest to the original pixel. A surface element density conversion processing method, wherein the density value of a pixel of an image is used as the density value of a converted pixel. 2. The surface element density conversion processing method according to claim 1, wherein the surface element density conversion processing is expansion conversion processing. 3. A surface element density conversion processing device for obtaining a desired target image by subjecting an original image, which is a digital image, to a surface element density conversion process at a desired conversion ratio. An input unit, an intermediate image generation unit that performs a surface element density conversion by a high-speed projection method, and creates an intermediate image from an original image according to a first conversion magnification, and an area image density conversion by a nearest neighbor method, and a second conversion magnification according to a second conversion magnification. A surface image density conversion including a target image generation unit that creates a target image from an intermediate image, and a magnification calculation unit that calculates the first conversion magnification and the second conversion magnification by allocating the desired conversion magnification. Processing equipment.