JPS61184687A - Control system of multilevel image magnification and reduction - Google Patents

Abstract

PURPOSE:To obtain an magnified/reduced image of excellent quality with simple circuitry by determining a luminance value of the converted image by the weighted average of the luminance values of the original image in the four points around the converted image and of the inverse number of the displacement of the point of the converted image from the said four points. CONSTITUTION:An address timing circuit 15 sets a converted image address (x+DELTAx, y+DELTAy) in a manner that its integer part x, y is in address holding circuits 11 and 13, and the decimal part DELTAx, DELTAy is in address holding circuits 12 and 14, also sets by means of a timing signal 26 the luminance value I1 of the original image from a 2-dimensional address memory circuit 10 in a holding circuit 16. Then the same circuit 15 sets I2 in a circuit 17 by setting x+1 in the circuit 11, I3 in a circuit 18 by setting x in the circuit 11 and y+1 in the circuit 13, and sets I4 in a circuit 19 by setting x+1 in the circuit 11 and y+1 in the circuit 13. Meanwhile, a distance- inverse generation table 20 generates the distance inverse numbers L1-L4 from DELTAx, DELTAy which are the multiplying numbers on the luminance values I1-I4 and outputs them. A data conversion table 21-24 outputs the products of I1L1-I4L4, which are added up by an adder 25. In result, the luminance I5 of the converted image of an accuracy equal to that of the original-image luminance I1-I4 is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-value image enlargement/reduction control method for enlarging/reducing multi-value plane single image data having shading.

[Conventional technology]

FIG. 2 is a diagram for explaining an algorithm for enlarging and reducing an image. In the same figure, +11. (2), +3
1゜(4) is the original image, (51 is the converted image, + in Figure 9)
The horizontal displacement from 11 to (5) is dx, and the vertical displacement is ay. Conversion surface # (from 51 to original image (
2) or (4) horizontal displacement is 1-dx,
The vertical displacement from the converted image (5) to the original image (3) or (4) is 1 - (17).
, +21.131. +41 brightness value by 1
．． Engineering 2. I3. Engineering 4. The brightness value of the converted image (5) is assumed to be 15.

The image enlargement/reduction algorithm uses horizontal displacement A
x, vertical displacement 6y and original image d brightness value 1. Engineering 2. Engineering 3. This is a method of determining the brightness value of the converted image from step 4, and several algorithms of this kind have already been proposed. This can be realized with a relatively simple circuit by using the brightness value of the original image closest to image (5) as step 5.

However, this method has a problem in that the stroke becomes thinner and continuity is lost during reduction.

The second method is luminance value processing 1. Engineering 2. Engineering 5. This method uses the logical sum of step 4 to determine the brightness value step 5 of the converted image, and this can also be realized with a relatively simple circuit, but it also has the problem that the stroke becomes thicker and the blurring of the figure becomes noticeable when it is reduced.

Several other algorithms have been proposed as well. Although a higher quality image can be obtained than the second method, there is a problem in that the circuit is complicated.

This invention was made in order to solve the above-mentioned problems, and aims to provide a multi-valued image enlargement/reduction control method that can obtain high-quality enlarged/reduced images with a simple circuit. be.

[Means for solving problems]

A multi-valued image enlargement/reduction control method according to the present invention.

means for holding the luminance values of the original image at four points around the converted image; and means for taking the reciprocal of the distance between the original image position and the converted image position at the four points around the converted image.

and means for taking a weighted average of each brightness value of the original image and the reciprocal of the distance.

[Effect]

The brightness value of the original image held by the above means, and the above means,
The reciprocal of the distance value obtained by υ is weighted averaged by the above weighted averaging means to determine the luminance value of the converted image.

〔Example〕

In Figure 1, αl is an x, y two-dimensional address memory circuit that stores the original image, (111, αz, 0. α4 is an address holding circuit that holds the address of the converted image in the original image, and (X+ΔX.

y+Δy), then X for αυ, ΔX for C2, y for 13, and Jy for C4), each value is set by the address-timing generation circuit α9. ! and 7 are the integer part of the converted image address, respectively, and ΔX'Δy is the decimal part.

(IS, aη, α seconds, (1g is the original image data holding circuit, and the holding timing (g) generated by the address timing circuit α9, respectively), fi, @, C1!!l are the luminance value processing of the original image. 1. Work 2. Work 3. Hold work 4.

Qυ, slope, C23, ff141 are data conversion tables, and the brightness values of the original image are calculated 1. Engineering 2゜ Engineering 3. The reciprocal number generated in the distance reciprocal generation table ■ for the process 4 is 1 y L2 +
This is a table for multiplying IJ5*TJ4. (c) is a data conversion table 3υ using an adder,
(2), @, (Foundation) conversion table output crab 1L1゜work 2L2. Engineering 3L3. Process 4L4 is added to obtain the luminance value of the original image Process 1° Process 2. Engineering 5. The brightness value of the converted image is rounded down to the same precision as step 4 and output as the brightness value step 5.

The address/timing generation circuit a9 generates x for αυ and Δ for +13 for the converted image address (X+Δ”+7+Δy).
Set y to X, 03, Jy to C4, and send the timing signal (
4), set the output data E1 of the two-dimensional address memory circuit α1 to the original image data holding circuit (Ie) 0, then set !+1 to (11), and set the output data E1 of the two-dimensional address memory circuit α1 to the original image data holding circuit Oη, and to αυ again! , set y+1 to Q3, and set 3 to the original image data holding circuit (I8, x+1 to αυ, y to C4
+1 is set, and 4 is set in the original image data holding circuit a9. On the other hand, the distance reciprocal generation table ■ is ΔX.

From Jy, the luminance value processing 1. Engineering 2. Engineering 3. Distance reciprocal value L1 to be multiplied by 4. II2. L5. Output L4.

In this case, for example, Ll is determined as follows.

The distance reciprocal generation table ■ is 1 for the input of ΔX and Δy.
/ Outputs the approximate value of (Jc)'+'(Jy)'.

The value of (Δ,)2+(Jy)2 changes from 0 to b.

Output L1i1. Ll-a for G, L for 6
j-0, and for values in between, adopt values obtained by linear approximation between 4 and 0 with the precision given to this circuit, and output them in place of @ΔI and Δy.

By using 1-Δx and 1-Δy, the distance reciprocal value L2
y J 5xJ4 is determined in the same way.

Data conversion tables ate, (2), ■, and aa are respectively
a e Output to the power Nf -Pull and add the output with an adder (c) to calculate the brightness value of the original image 1. Engineering 2. Engineering 3. The brightness value of the converted image is output with the same accuracy as step 4.

In the above embodiment, the structure of the distance reciprocal generation table ■ is determined by 1/677F767 houses, but 1/(Δ
x)2+(Jy)2 may be used as the reciprocal of the area instead of the reciprocal of the distance. Further, although the output is linearly interpolated between distances 0 and 0, it is also possible to approximate using some kind of function◇Also, these may be used in combination.

〔Effect of the invention〕

As described above, in this invention, the brightness value of the converted image is determined using a simple reciprocal table and a multiplication table, so that a single enlarged/reduced image with relatively good image quality can be obtained with a simple circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram for implementing a multivalued image enlargement/reduction control method showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining an algorithm for enlarging and reducing an image f. In the figure, cut is a two-dimensional address memory circuit. αB, α2. αJ, α4 are address holding circuits, acj
is the address/timing generation circuit, (171,
(Il, α value is the original image 1-image data holding circuit, ■ is the distance reciprocal generation table. Qυ, H, @, r241 is the data conversion table, (
C) is an adder.

Claims (1)

[Claims] A multivalued image enlargement characterized in that the brightness value of the converted image is determined by weighted averaging of the brightness values of the original image at four points around the converted image and the reciprocal of the displacement between the four original image positions and the converted image position. Reduction control method.