JPS6316944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image scaling method for reproducing a scaled image by performing arithmetic processing on digital image information obtained by scanning and sampling an image pixel by pixel.

Conventionally, in order to change the magnification, that is, to enlarge (or reduce) digital image information obtained by reading and sampling an image pixel by pixel, there is a method as disclosed in Japanese Patent Publication No. 53-39093, for example. , the entire image is processed by sequentially performing the necessary calculations for each pixel, the processing results for the entire image are temporarily stored in memory, and the contents are recalled to reproduce the scaled image. There is.

According to such a conventional method, in order to change the magnification of a digital image, as shown in FIG. 1, the pixel at position a is sampled again at position b, and then
Based on the basic principle that scaling of the image is achieved as a result, processing is performed using the calculations described below.

Now, let the pixels of the original image be represented by F(i, j),
The pitches are p _x and p _y , and the pixels of the variable magnification image are S
(k, l), and let the bits be q _x and q _y , then the four original image pixels F(i, j) and F(i+1, j) surrounding the scaling pixel S(k, l) , F(i, j
+1), F(i+1, j+1) to change the magnification pixel S
A method of representing (k, l) is used.

That is, in this method, first (i,
In order to represent the j) system and the (k, l) system using a common orthogonal coordinate system, parameter transformation is performed according to the following equation.

Δx＝q _x /p _x , Δy＝q _y /p _y ……(1) xi＝k・q _x ／p _x =k・Δx} ……(2) y _j =l・q _y /p _y = l・Δy i=[x _i ], j=[y _i ]...(3) However, [x _i ], [y _i ] are common coordinate system (x, y)
represents the largest integer that does not exceed x and y, respectively.

After such parameter conversion, the pixel S(k,l) of the variable scale image on the common coordinate system (x,y)
is calculated using the following formula.

S (k, l) = G (x _i , y _j )・F (i, j) + (Gx _i +1, y _j )・F (i+, j) + G (x _i , y _i +1)・F ( i, j+1) +G(x _i +1, y _j +1)・F(i+1, j+1)
...(4) In equation (4), G(x _i , y _j ), G(x _i +1,
Various functions are known that are used as y _j ), ..., and an example is shown below.

Here, K is a normalization constant.

Figure 2 shows a circuit configuration for concretely implementing such a conventional image magnification method.
The signals of each pixel sequentially read by the buffer memory 2 are sent to the buffer memory 2 and temporarily stored collectively, and the pixel signals F(i, j) to F(i+1, j+1) are stored. Parameter conversion is performed by the division circuit 3 that calculates the equation (1) and the multiplication circuit 4 that calculates the equations (2) and (3).
(5) The pixel S(k, l) of the scaled image is sequentially sent to the subtraction circuit 5 and absolute value calculation circuit 6 for calculating the equation (4), and the multiplication circuit 7 and addition circuit 8 for calculating the equation (4).
is calculated, and the result is stored in a buffer memory 9 over the entire original image and sent to an external output device (for example, a plotter).

At this time, if we focus on the fact that the amount of information per image changes before and after the scaling process, it is necessary to change clock A for image reading and clock B for arithmetic processing. If a general constant speed reading and constant speed output input/output device is used, the buffer memory 9 must have a large capacity.

The present invention has been made in consideration of the above points, and when a digital image signal obtained by scanning and sampling an image pixel by pixel is subjected to magnification processing by calculation, the input digital image is Only the main scanning direction of the signal is processed, and the sub-scanning direction is changed by controlling the paper feed of the output device (for example, a plotter) or the scanning speed of the image sensor/scanner on the input side. ,
The present invention provides an image scaling method that can reduce memory capacity on the output side and improve processing speed.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 shows an example of the configuration of an input/output device for concretely carrying out the image scaling method according to the present invention. , the reflected light is sent to the image sensor 1 via the mirrors M1, M2 and the lens L, and the read image information (electrical signal) is sent to the image processing circuit 13, where signal processing and arithmetic processing necessary for magnification are performed. After this, the processed signals are sent to the plotter control circuit 14 and the paper feed control circuit 15, respectively, to drive the plotter 16 and the paper feed device 17 for the recording paper P as appropriate. In the figure, reference numeral 18 indicates a scanner control circuit that performs scanning control of the scanner device comprising the mirror M2, lens L, and image sensor 1.

FIG. 4 shows an image processing process for executing the image scaling method according to the present invention using, for example, an input/output device as shown in FIG. direction value
Set p _x and q _x to set the variable magnification, and
In the process, the reduction rate Δx in the main scanning direction is calculated according to the set value. Next, in the third process, l = 1 is set to make the number of paper feed lines equal to the address in the sub-scanning direction, and in the fourth process, the paper feed pitch is set to q _y , and each of the fifth and sixth In the process, the address k in the main scanning direction after scaling is set to zero,
Also, the coordinate x in the main scanning direction is set to zero. Next, in the seventh process, x=x+Δx, and in the eighth process, i=[x] is calculated to perform parameter conversion, and then the coordinate position S(k,
In order to obtain l), the ninth to eleventh processes sequentially perform necessary operations. Then, by the 12th and 13th processes k=k+
When it is set to 1, it is determined whether k≧kmax, that is, whether k is at the maximum coordinate position of the image, and if not, the processing from the seventh process is repeated. Next, in the 14th and 15th processes, when l=l+1, it is determined whether l≧1max, that is, whether l is at the maximum coordinate position of the image, and if not, the fourth process is performed. The process is completed by repeatedly performing the above processes and finally stopping these processes. In this flowchart, the inner loop _L1 performs one cycle of processing per pixel, and the outer loop _L2 performs one cycle of processing per scanning line. In addition, in the arithmetic expression performed in the 11th process, G represents the contents stored in memory in advance for each address (D ₁ , Fi) and (D ₂ , Fi ₊₁ ), and the The contents are given, for example, as K/D ₁ ·Fi, as shown in FIG.

Furthermore, FIG. 5 shows an example of the configuration of the image processing circuit 13 shown in FIG. The incoming optical image information is sent to the delay circuit 19, where it is temporarily stored collectively in order to adjust the reading speed and processing speed of the input information (buffer function), and is sent to the A/D converter 20 to be converted into a digital signal. After being digitized, the contents are stored in the register 21. In addition, a separate system for executing each of the processes shown in FIG. 4 described above is incorporated, and a set signal (p _x , q _x ) for manually setting the image magnification as appropriate is provided from the outside. The second process operation Δx
₌ q _{x / p}
3 and a counter 24 that counts the output while circulating and calculates the position l in the sub-scanning direction.
According to the output of the division circuit 22, the seventh and eighth process operations x=x+Δx and i=
An addition circuit 25 that sequentially performs [x], an integer value conversion circuit 26, a counter 27 that counts the output of the integer value conversion circuit 26 to calculate the position k in the main scanning direction, and the output of the counter 27 and the addition A subtraction circuit 28 that performs subtraction of x-i and x-i-1 according to the respective outputs of the circuit 25 and the integer value conversion circuit 26, and each of the ninth and tenth processes that converts the results into absolute values. an absolute value calculation circuit 29 that executes the calculation, a quantization circuit 30 that samples its calculation output (sample will be sampled at a position in the main scanning direction after scaling), and its quantization output (D ₁ , D ₂ ) , a pixel-by _- pixel scaled image S(k,
l) according to the eleventh process; a plotter control circuit 14 that controls the plotter according to the output of the adder circuit 32 and each output of the counters 24 and 27; and the paper feed. It is constituted by a paper feed control circuit 15 or a scanner control circuit 18 that controls the paper feed device according to the output of the signal generation circuit 23. In addition, in the block shown in the figure, one cycle of processing is performed for each pixel, and in the block, one cycle of processing is performed for each scanning line.
It suffices that each block be processed at the output speed of the variable-magnification processed signal S(k, l), and the delay in processing time between each block will not be a problem.

As described above, regarding the image scaling method according to the present invention,
When the digital image signal obtained by scanning and sampling the image pixel by pixel is subjected to scaling processing by calculation according to the scaling command from the outside,
A system in which arithmetic processing is performed only in the main scanning direction of the digital image signal, and scaling is performed in the sub-scanning direction by controlling the paper feed of the recording paper on the output side or the image scanning speed on the input side. in,
Compared to conventional methods, the amount of memory required is significantly reduced, and the calculation content is simplified.
Moreover, it has the excellent advantage that the processing speed is improved and the structure of the entire device is simplified when it is put into practice.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of scaling a read image in pixel units, FIG. 2 is a block diagram showing an example of a configuration for executing a conventional image scaling method, and FIG. 3 is a diagram showing an example of image scaling according to the present invention. A simplified configuration diagram showing an embodiment of an image input/output device to which the method is applied, FIG. 4 is a flowchart of arithmetic processing in the image scaling method of the present invention,
FIG. 5 is a block diagram showing an example of a configuration for concretely executing the arithmetic processing, and FIG. 6 is a diagram showing an example of contents stored in advance in the memory. 1...Image sensor, 11...Document surface, 12
... Scanning lamp, 13 ... Image processing circuit, 14
... plotter control circuit, 15 ... paper feed control circuit, 18 ... scanner control circuit, 19 ... delay circuit, 20 ... A/D converter, 21 ... register,
22... Division circuit, 25, 32... Addition circuit, 2
6...Integer value conversion circuit, 27, 24...Counter, 28...Subtraction circuit, 29...Absolute value calculation circuit, 30...Quantization circuit, 31...Memory, 23
...Paper feed signal generation circuit.

Claims (1)

[Claims] 1. A first means for calculating a magnification ratio Δx according to a preset pixel pitch px of the original image in the main scanning direction and a pixel pitch qx of the variable magnification image, and a first means for calculating the number of feeding lines of the recording paper in the sub-scanning direction. In order to make it equal to the address of
a second means for setting the address k in the main scanning direction after scaling, a third means for setting the coordinate x in the main scanning direction to zero, and setting x=x+Δx in the main scanning direction. After calculating the pixel position i=[x] and performing parameter conversion, the coordinate position S(k, l) after scaling is determined by predetermined calculation processing based on the parameter-converted data. and a fourth means for repeatedly performing the fourth means, which determines whether or not k is at the maximum coordinate position of the image when k=k+1, and if k is not at the maximum coordinate position of the image. 5, and when k is at the maximum coordinate position of the image and l=l+1, it is determined whether l is at the maximum coordinate position of the image, and if l is not at the maximum coordinate position of the image, This is an image magnification changing method that includes means for repeatedly performing the processing from the second means.