JPH01277057A - Device and method for converting picture element density - Google Patents

Abstract

PURPOSE:To omit a multiplication circuit for density conversion and to perform a fast processing with a circuit of small scale by setting an area ratio by setting each density of a picture element group to be converted in n-ary expression as 1/width square of (n) in case of performing the picture element conversion of a multi-level image. CONSTITUTION:Assuming projecting neighboring picture element as A, B..., density as I, and the area ratio as W, the density of a conversion picture element R can be found in equation I. The density data of each picture element to be converted is inputted to multiplexers (131-134). At such a time, a division area deciding circuit 12 decides a division area to which the conversion picture element belongs by the position of the present conversion picture element on the flat plane of the picture element to be converted, and sends a decided result to the multiplexers (131-134). The multiplexers (131-134) and an arithmetic circuit 14 perform digit shift or computation based on a decided division area from the circuit 12, and obtain the density corresponding to the present conversion picture element. At the time of acquiring the density, by executing addition by adders (14a-14c) and equation I, it is possible to reduce the number of times of computation of the multiplication of I*W in equation I.

Description

[Detailed description of the invention] 〔table of contents〕 overview.

Background of the technology in the field of industrial application (Fig. 11.12) Conventional technology (Fig. 1.1, 12.13) Problems to be solved by the invention Means for solving the problems (Fig. 1, 2) Figure) Effect
(Fig. 1.2.11) Example (Fig. 3.4, 5, 6, 7, 8, 9゜10.11)
Figure) Effects of the invention [Summary] The density of each converted pixel is determined by a projection method from the density of nearby converted pixels according to the divided area in which the converted pixel is located, which is projected onto a plane on which the converted pixels are arranged. Regarding the pixel density conversion device and method, the present invention provides a pixel density conversion device and method for multivalued images that can perform high-speed processing with a small-scale circuit configuration by minimizing arithmetic operations, especially by reducing multiplication operations. For the purpose of providing, the density data of a predetermined group of converted pixels expressed in n-ary system located in the vicinity of the converted pixels is input, and based on the conversion magnification and the arrangement of the converted pixels, the density data is is the divided area in which the converted pixel is located among the divided areas set such that each density of the converted pixel group contributes to the density of the converted pixel according to the area ratio of each area having a size equal to one power of n. Based on the determined divided area, each density data of the converted pixel displayed in the n-ary system is shifted by digits, and the density data of the converted pixel is calculated from the shifted density data of each converted pixel. This is a configuration for calculating concentration.

(Industrial Application Field) The present invention relates to a pixel density conversion device and method, and in particular, the density of neighboring pixels to be converted is determined according to a divided area in which a converted pixel projected onto a plane on which pixels to be converted are arranged is located. The present invention relates to a pixel density conversion device and method for determining the density of each converted pixel by a projection method.

(Technical Background) In recent years, pixel density conversion devices for multivalued images such as halftones and full colors have been developed, especially for area ratio calculation and weighting in the projection method, which converts converted pixels from pixels to be converted without performing multiplication. There is a high-speed pixel density conversion device that you are looking for.

Current image processing systems often target not only black-and-white binary images but also multi-value images such as half-tone and full-color images, and enlargement/reduction techniques are indispensable when editing multi-value images. Among image input/output devices, half-tone and full-color scanners and printers (thermal transfer, electrophotography) are starting to recover, and pixel density conversion devices are playing an important role between devices with different resolutions.

Pixel density conversion device for multivalued images (image enlargement, reduction)
The projection method used as a recent example is a method of determining the density of a converted pixel from four pixels and adjacent converted pixels (
Journal of the Institute of Image Electronics Engineers, Volume 11, No. 2, 72-83.1
982).

FIG. 11 shows the principle of the projection method. Geometric mode conversion 1
In one projection method, first, the image plane to be transformed including four neighboring pixels A, B, C, and D is divided into four equal parts. The density of four neighboring pixels is I
,,I,,lc,ID, and when the converted pixel R is projected onto the pixel surface to be converted, the area ratios projected onto the quadrants are WA and WB.

W,, WI).

Then, the density of the converted pixel is expressed as ■R−Σ11* Wi; i=A, B, C, D・
... Determined by *.

Here, generally ΣW1=1.

Note that 1) and q in FIG. 11 are conversion magnifications in the X-axis and Y-axis directions.

In the projection method, the first step is to calculate the converted pixel density.
Shown in Figure 2.

(Prior Art) Conventionally, FIG. 12 shows a processing procedure for calculating the converted pixel density when pixel density conversion is performed by a projection method.

■ Coordinates of converted pixel R on the converted pixel surface (X.

Y) is calculated.

(2) Calculate the projected area ratios WA, WB, We, and Wo from the coordinates (X, Y) and conversion magnifications p and q.

■ Density IA+In of 4 pixels A, B, C, D to be converted
, IC,10 and each area ratio WA determined by ■.

The density of the converted pixel R is calculated from w, , We, and Wo according to the formula*.

■Conversion pixel R density 1. Output.

Next, FIG. 13 shows a block diagram of an area ratio calculation circuit and a product-sum calculation circuit (corresponding to the processing steps ① and ①) based on the projection method.

In this example, as shown in FIG. 13, the density data I/I of the converted pixels located in the four converted pixels A, B, C, and D shown in FIG. 11 near a predetermined converted pixel, IB, Ic, II
An input means for inputting I into each multiplier 331, 332, 333, 334, an area ratio calculation circuit 312 for calculating the area ratio where the current converted pixel is located, and each area ratio WA, Wa obtained by the circuit 312. , Wc, Wo and four converted pixels A, B, located near the converted pixel,
C.

Multipliers 331, 332, 333, and 334 that multiply D by the density data IA, 1B, IC, and 10; and an adder 31 that adds the multiplication results of the multipliers 331 and 332.
4a, an adder 314b that adds the multiplication results of the multipliers 333 and 334, and an adder 314c that adds the addition results of the adders 314a and 314b.

The area ratio calculation circuit 312 calculates the position coordinates X of the converted pixel,
From the value of Y and the sign between them and p and q, (0,5+p
x)*(0,5+qy), and calculate each area ratio WA,
WB, We, and Wo are determined, and the multiplication circuit 331.
332, 333, 334 and addition circuits 314a, 314b
, 314c.

Therefore, in the entire circuit of Fig. 13, the multiplication is 3x4+4=1
This means that addition and subtraction will be performed 6 times and 2x4+3=11 times.

[Problem to be solved by the invention]

By the way, conventionally when converting pixels,
When calculating the density of one converted pixel, if sequential processing were performed, 27 arithmetic operations would be required, making it impossible to perform high-speed calculations.

In addition, when performing parallel processing, a pipeline configuration must be adopted in which 16 multiplication circuits are used alone, resulting in a problem that the circuit scale becomes enormous.

Therefore, the technical object of the present invention is to solve the above problems, and by reducing arithmetic operations as much as possible, especially multiplication operations, high-speed processing can be achieved with a small-scale circuit configuration. The purpose of this invention is to provide an apparatus and method for converting pixel density of a multivalued image.

[Means to solve the problem]

In order to solve the above-mentioned technical problems, the first invention is based on the divided area in which the converted pixels are projected onto the plane where the converted pixels are arranged, as shown in FIG. In a pixel density conversion device that determines the density of each converted pixel from the density, a converted pixel input means 1 inputs density data of a predetermined group of converted pixels expressed in an n-ary system located in the vicinity of a converted pixel; Based on the conversion magnification and the arrangement of the pixels to be converted, it is assumed that within that area, each density of the group of pixels to be converted contributes to the density of the converted pixel by an area ratio having a magnitude of 1 of the corresponding power of n. divided area determining means 2 for determining in which divided area of the set divided areas the converted pixel is located; and the converted area displayed in an n-ary system based on the divided area determined by the determining means 2. Digit shifting means 31, 32, and 32 for shifting the digits of each density data of a pixel.
....

3m, and an arithmetic means 4 for calculating the density of the converted pixel from the density data of each converted pixel shifted by the digits by the digit moving means 31, 32, . . . , 3m.

The second invention is a pixel density conversion method in which the density of each converted pixel is determined from the density of neighboring converted pixels according to the divided area in which the converted pixel is located projected onto a plane on which the converted pixels are arranged, A process (S1) of sequentially inputting the density data of a predetermined group of converted pixels located in the vicinity of the pixel and displayed in the n-ary system, and based on the conversion magnification and the arrangement of the converted pixels, Determine in which divided region the converted pixel is located among the divided regions set as contributing to the density of the converted pixel according to the area ratio in which the density of the converted pixel has a size equal to one power of the corresponding n. (S2), and a step (S3) of shifting the digits of each density data of the converted pixel displayed in the n-ary system based on the determined divided area;
This process includes a step (S4) of calculating the density of the converted pixel from the density data of each converted pixel that has been shifted by digit.

(effect) A detailed explanation of the first and second inventions will be given.

When converting the pixel density according to the present invention, as shown in FIG. 1 and FIG. The converted pixel input means 1 sequentially inputs each density data of the converted pixel expressed in n-ary system (in most cases, binary system) located in the vicinity of the converted pixel to the relevant pixel conversion device. do. Here, the nearby pixels to be converted are, for example, four pixels A, B, C, and D surrounding the converted pixel as shown in FIG. 11.

In step S2, the divided area determination means 2 determines the divided area in which the converted pixel is located.

Here, the "divided area" is based on the conversion magnification and the arrangement of the converted pixels as described above, and within that area, the width (power) of n is divided for each density of the converted pixel group. This is an area that is set to contribute to the density of the converted pixel by an area ratio having a dog size.

Furthermore, "contributing" is not necessarily limited to contributing by an accurate area ratio determined by the position of the converted pixel, but may be treated as contributing if a certain degree of contribution tendency is taken into account. .

The influence of the density of a pixel to be converted on the density of a certain converted pixel is given by the above-mentioned formula*.

Furthermore, as mentioned above, the "area ratio" means, for example, when the nearby pixels to be converted are A, B, C, and D, the density IA+ of each converted pixel is relative to the density In of the converted pixel R.
WA, WB displayed as coefficients of l1lIC+IO
, We, and Wn.

In step S3, the divided area determining means 2 makes a determination and gives a digit moving instruction to the digit moving means 31, . . . , 3m based on the divided area.

Here, m indicates the number of converted pixels located in the vicinity of the converted pixel, and in the normal projection method, m
= 4.

That is, each digit moving means 31. ...3m is provided for each pixel to be converted located in the vicinity of the pixel to be converted, and digits are shifted independently for each pixel to be converted based on the divided area in which the pixel to be converted is located. That will happen.

- This is because, as mentioned above, the influence of the density of each converted pixel on the density of the converted pixel is made to correspond to each divided area by the area ratio carved by the power of n, so multiplication etc. This is because the influence from each pixel to be converted can be obtained only by shifting the digits without performing calculations.

In step S4, the calculating means 4 can calculate the density of the target conversion pixel based on the influence of the density obtained for each pixel to be converted.

For example, when the calculation of the density of the converted pixel is performed based on the above-mentioned formula*, only addition is required, and the calculation is greatly simplified.

(Example) First example> Next, a first embodiment of the present invention will be described.

A pixel conversion device according to this example is shown in FIG.

As shown in the figure, this example is located near a predetermined converted pixel read out by a converted pixel input means such as a camera that directly reads the converted image or a transmission means that transmits data from a host computer, etc. 4 pixels A and B as shown in FIG.

Digit shift means 31.3 that inputs each density data of the pixel to be converted expressed in the binary system C, D, In, I(j (1) and performs digit shift (bit shift) on the density data.
4→1 multiplexer 131 as 2,33.34,
132, 133, 134, and an area determination circuit 1 that determines the divided area to which the currently targeted converted pixel belongs.
2, and an arithmetic circuit 14 as an arithmetic means 4.

The arithmetic circuit 14 includes the 4→1 multiplexer 131.
an adder 14a that adds the digit shift results from 132, an adder 14b that adds the shift results of the 4→1 multiplexers 133 and 134, and the adders 14a, 14.
It has an adder 14c that adds the addition results of b.

Here, the density of the pixel to be converted is not simply binary data representing black or white, but is intended for multivalued images such as halftones and full color, and each density is expressed with 4 bits. It is assumed that

FIG. 4 shows the multiplexer 131 in detail.

The multiplexer 131 inputs each digit of the multi-level density data expressed in 4 bits of the input pixel to be converted. ＋IA
I + IA2 Multiplexers 131a, 131b, 131c, and 131d provided for each HIA3, and each multiplexer 131 based on the divided area in which the current converted pixel sent from the divided area determination circuit 12 is located.
It has a decoder 131e for transmitting information necessary for performing digit shift for a, b, c, and d.

In this embodiment, the divided areas shown in FIG. 5 or 6 are used as the divided areas. Also, in the above formula*, p,
Regarding q, I)=Q=1 is set to simplify the calculation, and in the case of enlargement, it also has a smoothing effect on an image with edges in the diagonal direction.

In the divided area group 1 shown in FIG. 5, when the coordinates of the converted pixel are (X, Y),
≧O, Y≧0) Two area ratio W. Curve when =172■ Area (0,5+X)*(0,5+Y)≧0.5
(G3) ・Since the area ratio We = 1/2 or more, it is approximated by only 1°■ Area (0,5+X)*(0,5+Y) <0.5(
G9, Gto) Since the two area ratio W, = less than 1/2, it is expressed as a combination of IA, IB, IC, and In.■ Straight line Y=X: Select the second closest pixel and give it an area ratio of 1/4. straight line■ Y≧X(G
9): WA = 1/8. Wa=1/4. Wc
=1/2. Give WD=1/8.

■ Y < X (Glo): WA = 1/8.
Wn=1/8. Give Wc=1/2 and WD=1/4.

Furthermore, FIG. 6 shows a divided area group 2 which is a further simplified version of the divided area 1 shown in FIG.

Divided area group 2 is created by replacing the curved boundary line that divides each divided area group 1 shown in FIG. 5 with a straight line, thereby simplifying the judgment conditions and making it possible to perform faster processing. .

In divided area group 2 shown in Figure 6, ■ Straight line X+Y
=0.5 (X≧O, Y≧O): Area ratio W. =1
72, considering diagonal line smoothing and calculation simplification■ X+Y≧0.
5 (G3): Area ratio W. = 172 or more, so I
Approximate with only c @X+Y<0.5 (Gs, Gto): Area ratio W
Since c=less than 172, 1. , lI3,1. , Expressed by combining IDs ■ Straight line Y=X: Select the second closest pixel,
A straight line to give an area ratio of 1/4 to that ■ Y
≧X (G9): WA=1/8, Wa=1
/4, Wc=1/2, W,=1/8 are given.

■ Y < X (G 10): WA = 1/8
．． Wn=1/8, Wc=1/2, WD=1/
Give 4.

In addition, in the divided region groups 1 and 2 shown above, the converted pixel plane is divided using straight lines X=0 and Y=0 as boundary lines, and the above description is based on the assumption that X≧0.
This is not limited to Y2O, and also holds true when X→-X or Y→-Y.

Next, the operation of this embodiment will be explained.

When calculating the density of a converted pixel according to this embodiment, the converted image is read by the converted pixel input means such as the transmission means, and the density data of the converted pixel located in the vicinity of the current converted pixel is input. .

The input density data of each pixel to be converted is input to the multiplexers 131, 132, 133, and 134.

At this time, the divided area determination circuit 12 as the divided area determination means 2 determines the divided area to which the converted pixel belongs based on the position of the current converted pixel on the converted pixel plane.

In this example, divided area group 1 is set as shown in FIG. 5, and determination for each divided area is performed based on the conditions shown in Table 1.

Table 19 Division Conditions for Viewing Area Group 1 Note: For areas on the boundary line, one of the multiple areas may be selected in advance.

Furthermore, the determination based on the divided area group 2 shown in FIG. 6 will be made based on Table 2.

It is sufficient to select one in advance.

FIG. 7 shows the processing procedure (steps 5R71 to 5R82) when the divided area determination circuit 12 makes a determination in the case where the determination is made based on the divided area group 2.

In the divided area determination circuit 12, whether X≧0 or not, Y
20, whether X0Y≧0.5, and whether Y≧X, it is easy to determine which divided area the current converted pixel belongs to.

In addition, X+Y≧0.5, X regarding whether Y≧X,
The sign of Y depends on whether X≧0 or not and whether Y2O or not.

Information regarding the divided area determined in this manner for the divided area to which the current converted pixel belongs is sent to the multiplexers 131, 132, 133 and 134 as 4-bit information.

The multiplexers 131 and 132 that received the information
, 133, 134 decoders 131a (132a, 1
33a, 134a) is converted into 2-bit information (information specifying 0.1, 2.3 of each multiplexer) necessary for performing the corresponding digit shift based on the divided area, and is sent to each multiplexer 131a. , 131b, 131c.

131d etc.

The multiplexers 131, 132, 133° 134 and the arithmetic circuit 14 shift digits based on the divided area determined by the divided area determination circuit 12 in order to obtain the density corresponding to the current converted pixel from the density data of the converted pixel. Or it is something that performs calculations.

Table 3 shows, for each divided area, the densities of the pixel group to be converted when the current converted pixel is located in the divided area.
The contribution to the density of the converted pixel is described through each area ratio having a size of 1/2.

In other words, each area ratio WA, Wa of the above formula*
. is the divided area G, G2. G3. In the case of belonging to G4, as shown in Table 3, it is sufficient to consider the influence of only the converted pixels A, B, C, and D that are closest to each divided area. Therefore, when the current converted pixel belongs to the divided area G, the decoder 131e of the multiplexer 131 shown in FIG. 4 is connected to each multiplexer 131a.

A signal to select 3 is sent to 131b, 131c, and 131d to prevent any digit shift.

Furthermore, when it is determined that the current converted pixel belongs to divided area 05, as is clear from Table 3, the contribution from the density IA of pixel A to the density of the converted pixel is on the order of 1/2. Therefore, the density data of the relevant pixel A)! (expressed in binary notation) only needs to be shifted by one digit.

Therefore, the decoder 13 of the multiplexer 131
1e is each multiplexer 131a.

It is sufficient to select 2 in 134b, 131c, and 131d.

In addition, as is clear from Table 3, the divided areas are G2, G
3, G4, the multiplexer 131 does not select anything, and when the divided area is 06, 2 is selected in FIG. 4, and when the divided area is G7. In the case of Gl□, G13, 1 is selected in Fig. 4, and the divided area is Ga.
, G9, Gt. , G1□, 0 is selected in FIG.

Thus, the multiplexer 131°132.133
.
The above-mentioned formula * is executed, and the density of the current converted pixel is determined.

As explained above, in this embodiment, when determining a region, the divided region determining circuit 12 requires one addition and two comparisons, and the calculation circuit 14 requires a total of three additions. It is only necessary once, and also option 4
This means that the number of operations required for the I=l:W multiplication shown in the formula * is greatly reduced compared to the conventional method.

Second embodiment> Next, a second embodiment will be described.

In this embodiment, the figure 5 or 6 set in the first embodiment is used.
Instead of setting the divided regions shown in the figure, the divided regions shown in FIG. 8 or 9 are set, and the determination is made based on the divided regions. The divided area according to this example takes into account the contribution of the density of the converted pixel to the density of the converted pixel more accurately than the divided area according to the first example.

The divided area group 3 shown in FIG. 8 is set as follows.

■ Curve (0,5+X), (0,5+Y)=0.75(
X≧0. Y≧0) = A curve in which the area involved by Ic is 374 or more (If the area is 172, it is considered that the influence of other pixels is strong, so the area is about 3/4 between 1 and 1/2. (It is defined as the boundary.) ■ Area (0,5 +
G, ): Since the area involved by Io is 374 or more, it is approximated by looking at Ic ■ Area (0,5+X) * (0,5+Y) <0.75
(G9, G,.) = lA, IB since the area involved by IC is less than 374.

Expressed by combining IC and ID■ Curve (0,5+X)1:(0,5+Y)=0.33
(X≧0.Y≧0): The area involved by Ic is 1
73 (this comes from the idea that if the area is 173 or less, the effects of other images are considered to be almost the same, and the same area ratio for four pixels is fine.

)■ Area (0,5+X)*(0,5+Y) <0.3
3 (G3): The area involved by Ic is 173 or less, so the same area ratio WA = 1/4, WB = 1/4
, Wc=1/4, and Wo4/4 are given.

■ Area (0,5+X)*(0,5+Y)≧0.33
(G9. G Engineering): W because the area involving Io is 173 or more.

= 172 and the rest are IA, In, Ic, I. Expressed as a combination of

■ Straight line Y=X: This is a straight line for selecting the second closest pixel and giving it an area ratio of 1/4.

■ Y≧X (G9): WA=1/8. W
,=1/4. W, = 1/2. Give W, = 1/8.

■ Y < X (G □o): WA = 1/8
．． Wn=1/8. Give Wc=1/2 and WD=1/4.

Each of the divided regions 01 to G shown above. Table 4 shows the conditions for determination.

Table 4 Classification conditions for divided viewing area group 3 It is best to make your selection in advance.

Next, divided area group 4 shown in FIG. 9 will be explained.

Divided area group 4 is a further simplified version of divided area group 3.

■Straight line X+Y=0.75 (X≧0.Y≧O): Ic
The area involved in Ic is 374, taking into consideration diagonal smoothing and calculation simplification■ X+Y≧0.75 (G3): The area involved in Ic is 374 or more, so ■. Approximate by only ■ X+Y <0.75 (G9, Gto):
Since the area involved by Ic is less than 374, IA, In,
Expressed by the combination of Ic and Io■ Straight line X+Y=0.33 (X ≧0.Y≧0):
1. The area involved is 173, taking into consideration diagonal line smoothing and calculation simplification■ X+Y <0.33 (G3): I
Since the area involved in c is 173 or less, the same area ratio WA = 1/4°Wn"1/4, Wc = 1'/4
, gives Wo=174.

■ X+Y≧0.33 (G9, Gto): Ic
Since the area involved is 173 or more, W c = 1
/ 2 and the rest is expressed as a combination of IA, In, IC, I[l.

■ Straight line Y=X: Straight line to select the second closest pixel and give it an area ratio of 1/4■ Y≧X
(G9): WA=1/8, WB=1/4
, Wc=1/2, WD=1/8 are given.

■ Y < X (Gro): WA = 1/8.
Give Wn=1/8, Wc=1/2, and WD=1/4.

Table 5 shows the conditions for determining the divided regions G□ to G□3 shown above.

It is best to select it in advance.

The operation of this embodiment will be performed based on Table 4 or Table 5 using the apparatus shown in FIG. 3 or 4 in the same manner as shown in the first embodiment. Since this is the same as the embodiment, the explanation will be omitted.

In addition, in the divided area groups 3 and 4 shown above, the converted pixel plane is divided using straight lines x=o and y=o as boundary lines, and the above explanation is based on the assumption that X≧O,
This is not limited to Y2O, and also holds true when X→-X or Y→-Y.

When dividing area group 4 is set, unlike when dividing area group 3 is set, the dividing area determination circuit 22 determines whether X≧0 or not, Y2O or not, x+y≧0.75 or not, and X+Y.
By checking whether or not ≧0.33 and whether Y≧X or not, the divided area to which the current converted pixel belongs is determined, and the conditions for determination are simple.

In the case of divided area group 4, the divided area determination circuit 2
The determination processing procedure (steps 5R101 to 5R115) in step 2 is shown in FIG.

The number of calculations in this embodiment is one addition performed in the divided area determination circuit 22, three comparisons, three additions in the arithmetic circuit 14, and four selections for the multiplexers 131 to 134. Therefore, the number of times is 11 in total, and since each comparison process is performed independently in the divided area determination circuit 22 (12), there is no need to use pipeline processing and it can be realized with a small-scale circuit configuration.

In addition, in the first and second embodiments, each area ratio can be summarized as follows.

For a certain pixel to be converted on the pixel surface to be converted, first, for the divided area closest to the pixel to be converted, only the area ratio to the density of the pixel to be converted is set to 1, and second, For the divided area that is the second closest to the converted pixel, the area ratio to the density of the converted pixel closest to the divided area is 172, and the area ratio to the density of the converted pixel that is the second closest to the divided area is 1742. and the area ratio for the density of the remaining two pixels to be converted is 178. Thirdly, for the divided area in the center of the four pixels to be converted, the area for each density of the four pixels to be converted is The ratio is equal to 174 for each.

As explained above, in the first and second embodiments,
When determining divided regions as shown in FIG. 6 or FIG. 9, the region determination part does not include multiplication processing due to calculation simplification, and each comparison processing can be performed independently. It is also possible to output the converted pixel density in one cycle.

〔Effect of the invention〕

As explained above, in the present invention, when converting (enlarging, reducing) the pixel density of a multivalued image, the area ratio W is set to - of the power of n (in most cases, 2). The multiplication I*W of the density 2 of the pixel to be converted by W, which is necessary when calculating the density of the converted pixel, can be performed by only bit shifting or downshifting, and the multiplication circuit can be omitted.

Therefore, it is possible to realize dramatically high-speed processing with a small-scale circuit.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the principle of the first invention, Figure 2 is a flowchart of the principle of the second invention, Figure 3 is a block diagram of the first and second embodiments, and Figure 4 is a diagram of the pixels to be converted. A diagram showing a 4→1 multiplexer in the case of density IA (4 bits), FIG. 5 is a diagram showing a divided area group 1 according to the first embodiment, and FIG. 6 is a diagram showing a divided area group according to the first embodiment. 2, FIG. 7 is a flowchart of the divided area determination process of Table 2 according to the first embodiment, and FIG.
The figure shows the divided area group 3 according to the second embodiment, the diagram shows the divided area group 4 according to the second embodiment, and FIG. 10 shows the divided area determination of Table 5 according to the second embodiment'. Processing flowchart, 1st
FIG. 1 is a diagram showing the principle of the projection method, FIG. 12 is a flowchart showing the processing procedure of the projection method, and FIG. 13 is a block diagram according to a conventional example. 1... Converted pixel input means 2 (12, 22)... Divided area determination means (divided area determination circuit) 31-3m (131-134)... Digit shift means (4→
1 multiplexer) 4 (14)...Arithmetic means (arithmetic circuit) Principle flowchart of the second invention 2nd! ! I Ward 3 PX3 Work A [4 pits] case! ,! Input No. 1 Secondary bow two-thread light setting (method) 1. Display of case Patent application No. 106849 of 1988 2, Title of invention Pixel density conversion device and method 3,
Relationship with the case of the person making the amendment Patent applicant address 1015 Kamiodanaka, Nakahara-ku, Yozaki City, Kanagawa Prefecture Name (522) Fujitsu Ltd. 4, Agent Address: 105

Claims (2)

[Claims] (1) In a pixel density conversion device that uses a projection method to determine the density of each converted pixel from the density of neighboring converted pixels according to the divided area in which the converted pixel is located, projected onto a plane on which the converted pixels are arranged. , a converted pixel input means (1) for inputting density data of a predetermined group of converted pixels expressed in an n-ary system located in the vicinity of the converted pixels; Which of the divided regions is set such that each density of the converted pixel group contributes to the density of the converted pixel by each area ratio having a size of one part of the corresponding power of n within the region? divided area determining means (2) for determining whether the converted pixel is located in the area; and each density data of the converted pixel displayed in an n-ary system based on the divided area determined by the determining means (2). A digit moving means (31, 32..., 3m) that moves the digits of A pixel density conversion device characterized by having a calculation means (4) for calculating. (2) In a pixel density conversion method in which the density of each converted pixel is determined by a projection method from the density of neighboring converted pixels according to the divided area in which the converted pixel is located projected onto a plane on which the converted pixels are arranged, Step (S1) of sequentially inputting the density data of a predetermined group of converted pixels located in the vicinity of the converted pixel and displayed in n-ary system; and based on the conversion magnification and the arrangement of the converted pixels, In which divided region is the converted pixel located, which is set such that each density of the converted pixel group contributes to the density of the converted pixel by each area ratio having a size equal to one power of the corresponding n? The process of determining whether S is located (S
2), a step (S3) of shifting the digits of each density data of the converted pixel displayed in the n-ary system based on the determined divided area; A pixel density conversion method comprising the step of calculating the density of the converted pixel (S4).