JPH04340997A - Image scaling method - Google Patents

Abstract

PURPOSE:To set optional magnification and to shorten a scaling time even when data is written in a display area by (n) picture elements at each time. CONSTITUTION:A magnification conversion part 13 divides an image IMGi stored in an input memory 11 into a 1st subordinate image SIMa of maximum size which can be scaled and a 2nd remaining subordinate image SIMb unless the number of picture elements obtained by multiplying the number of horizontal picture elements of the stored image IMGi by S is not an integral multiple of (n), multiplies the 1st subordinate image by S, and writes the image in the display area 12a of a display memory 12 in (n)-picture-element units. Further a dummy image DMI is added to the 2nd subordinate image SIMb to enable its scaling, and its composite image is multiplied by S and written in a nondisplay area 12b in (n)-picture-element units. An image processing part 14 writes the image SIMb', obtained by multiplying the 2nd subordinate image by S and written in the nondisplay area 12b through software, is written at corresponding positions of the display area 12a and the scaled image is all stored in the display area 12a and displayed on a display screen.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image scaling method for an image drawing device, and in particular, it involves storing an image in an input memory, multiplying the image by S, and writing it into a display area of a display memory in units of n pixels. The present invention relates to an image scaling method for an image drawing device that reads and displays an image from a display area.

0002

[Prior Art] With the shift to multimedia in pass capacitors/workstations, a system has been developed to display natural images (images in 16.7 million colors) in addition to conventional media such as letters and figures on the screen of a personal computer. is progressing. In such systems, natural images are input at a fixed size from scanners, industrial cameras, video cameras, etc.

[0003] In a system that handles images containing a mixture of characters, figures, and natural images, it is required to enlarge or reduce the input natural image to an arbitrary size by scaling and display the image. For this reason, conventionally, an image input from an image generating device such as a scanner is temporarily stored in an input memory, and then
The image is multiplied by S (=m/16) in a magnification converter and written in n pixel units (for example, 4 pixel units) in the display area of the display memory, and the image is read out from the display area and displayed on the CRT. .

0004

[Problem to be Solved by the Invention] However, in most inexpensive systems, natural images are displayed at the input size, and even in systems that perform scaling display, it is difficult to change the scaling factor, the number of input pixels, or the display size. There is a limit to the number of pixels. Figure 5 is an explanatory diagram of the magnification limit, where IMGi is the input image (natural image), I
MGd is the displayed image, Xs is the number of pixels in the horizontal direction of the natural image (original image size), and Xd is the display size of the natural image (number of pixels in the horizontal direction of the displayed image).

[0005] Since it is necessary to write an image multiplied by S into the display memory in units of n (=4) pixels, Xd must be a multiple of n (=4). That is, Xs×S=Xd=4·N (1) must hold true. For this reason, it is not possible to set an arbitrary magnification as S (=m/16), and there is a problem in that the magnification at which equation (1) is satisfied is limited.

From the above, it is an object of the present invention to store n in the display memory.
An object of the present invention is to provide a scaling method for an image drawing device that can set an arbitrary magnification even when writing pixel by pixel.

[0007]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. 11 is an input memory for storing an image IMGi input from an image generating device such as a scanner; 12 is a scale;
A display memory that stores a ringed display image and has a display area 12a and a non-display area (work area) 12b. A magnification conversion section 14 writes in pixel units (for example, 4 pixel units), and 14 is an image processing section that writes the image of the non-display area 12b into the display area 12a using software.

[0008]

[Operation] The magnification conversion unit 13 determines whether the number of pixels obtained by multiplying the number of pixels in the horizontal direction (■+■) of the image IMGi stored in the input memory 11 by S is an integral multiple of n, and determines whether the number of pixels is an integral multiple of n. In this case, the first sub-image SIMa whose size is an integer multiple of n when multiplied by S at maximum, and the remaining second sub-image SI
An image SIMa' obtained by dividing the first sub-image SIMa into Mb and multiplying the first sub-image SIMa by S is written in the display area 12a of the display memory 12 in units of n pixels, and the second sub-image SIMb has a horizontal pixel count of α. By adding a dummy image DMI, S・(■+α) is made to be an integral multiple of n,
The composite image of the second sub-image and the dummy image is multiplied by S and n
It is written in the non-display area 12b of the display memory 12 pixel by pixel, and then the image processing unit 14 software displays only the image (shaded area) obtained by multiplying the second sub-image written in the non-display area 12b by S. All the images written and scaled at the corresponding positions in the area 12a are stored in the display area 12a and displayed on the display screen.

[0009] In this way, the first sub-image SIMa is the largest possible size that can be scaled, and the remaining second sub-image SIMb is divided, and the first sub-image is multiplied by S and displayed in the display area. - The second sub-image is written at high speed by the hardware and drawn immediately, and a dummy image is added to the second sub-image to make it scalable. Since the second sub-image is written to the display area in a practical manner, when writing n pixels at a time to the display area, any magnification can be set without changing the hardware or increasing the circuit scale. In addition, the first sub-image can be drawn at high speed, and the processing time can be shortened compared to performing all scaling processing using software.・Copying) can be realized.

0010

【Example】

Overall configuration FIG. 2 is a configuration diagram of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. In the figure, 11 is an input memory that stores images input from an image generating device such as a scanner, and 12 is a display memory that stores scaled images. It has a display area (work area) 12b.

13 converts the input image into S(=m
/16) and stores it in the display memory 12 in units of n pixels (for example, 4
It is a magnification converter that writes in pixel units.
It is composed of software (software). Reference numeral 14 denotes an image processing unit that controls the entire system and also performs processing of writing the image of the non-display area 12b into the display area 12a using software.
5 is a parallel/serial conversion unit (P/
S), 16 is a CRT.

Scaling control FIG. 3 is a flow chart of scaling control, and FIG. 4 is an explanatory diagram of scaling control. In FIG. 4, IMGi is an input image stored in the input memory 11, and IMGd is an input image displayed on a CRT The display image to be displayed, S (=m/16), is the magnification. still,
Number of pixels in the horizontal direction of input image IMGi Xs (=■+■)
is 352, and the magnification S (=m/16) is 25/16 (m=2
5).

When the magnification converter 13 receives the magnification S, the horizontal pixel number Xs of the input image IMGi, the storage position of the input image in the input memory 11, etc. from the image processor 14, the magnification converter 13 converts the input image IMGi in the horizontal direction. Number of pixels Xs (■+■
Display image IMG obtained by multiplying =352) by S (=25/16)
It is determined whether the number of pixels in the horizontal direction Xd (=550) of d is an integer multiple of n (=4), in other words, the number of pixels Xs (■+■=352) of the input image IMGi can be scaled. The number of pixels is determined (step 101, see FIG. 4(a)).

If it is an integral multiple of n, the input image IMGi is multiplied by S and written into the display area 12a of the display memory 12 in units of n (=4) pixels, and the scaling process is completed (step 102).

However, as shown in FIG. 4, Xd is n (=4
), the maximum size is S(=25
/16) Divide into the first sub-image SIMa, which becomes an integral multiple of n (=4) when multiplied, and the remaining second sub-image SIMb (step 103). Note that the first sub-image SIMa
If the number of pixels in the horizontal direction is ■, then from equation (1),
■×(m/16)=4・N (N is any integer)
...(2) holds true. In order for equation (2) to hold true, if ■/16 is an integer, the value of each side of equation (2) must be 4.
So that it is an integer multiple of the least common multiple (=100) of and m,
It is sufficient to determine ■ which is smaller than Xs.

Therefore, in the case of the example, the least common multiple is 10
Since it is 0, ■×(25/16)=100・N'(N' is any integer) ... (3) holds, and from equation (3), ■=64・N'≦352 ... ( 4) is obtained,
The maximum ■ that satisfies equation (4) is 320. Therefore, the number of pixels in the horizontal direction of the second sub-image SIMb is 32 (=352-320).

[0017] See FIG. 4(a) above.

Next, the first sub-image SIMa is converted to S(=2
5/16) Number of pixels in the horizontal direction multiplied by S・■ (=50
0) is written in the display area (screen area) 12a of the display memory 12 in units of n (=4) pixels (steps 104 to 105, see FIG. 4(b)). Due to the above,
Thereafter, the images SIMa' are sequentially read out, parallel-to-serial converted, and displayed on the CRT 16, so that the scaled image of the first sub-image can be immediately viewed.

Thereafter, by adding a dummy image DMI with α horizontal pixel count (see (c) in FIG. 4) to the second sub-image SIMb, S・(■+α) becomes n(=4 )
In other words, the number α of pixels in the horizontal direction of the dummy image DMI, which is the number of pixels that can be scaled, is determined (step 106). In the case of the example, 32
It is sufficient to find the minimum α that satisfies +α=64·N', which results in α=32.

Once α is determined, the composite image of the second sub-image SIMb and the dummy image DMI is multiplied by S (=25/16) and the non-display area (work area) of the display memory 12 is ) 12b (steps 107-108, Figure 4
(c)).

[0021] When writing to the non-display area 12b is completed,
The image processing unit 14 uses software to write only the image SIMb', which is obtained by multiplying the second sub-image written in the non-display area 12b by S, at the corresponding position in the display area 12a (step 1).
09, see Figure 4(d)).

As described above, the scaled display image I
Display area 1 for all MGd (=SIMa'+SIMb')
This means that it is stored in 2a. Thereafter, the scaled display images SIMd are sequentially read out from the display area 12a, subjected to parallel-to-serial conversion, and displayed on the CRT 16.

The present invention has been explained above using examples, but
The present invention can be modified in various ways according to the gist of the present invention as described in the claims, and the present invention does not exclude these modifications.

[0024]

As described above, according to the present invention, the first sub-image is divided into the maximum scaleable first sub-image and the remaining second sub-image, and the first sub-image is displayed multiplied by S. Write to the area at high speed using hardware and draw immediately.
For the second sub-image, a dummy image is added to make it scalable, and hardware writes it to the non-display area at high speed, and then software writes the second sub-image to the display area. Since it is configured to write n pixels into the display area, any magnification can be set without changing the hardware or increasing the circuit scale. Images can be drawn at high speed, and the processing time can be shortened compared to when all scaling processing is done using software, making it possible to edit natural images (move and copy with scaling). can.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is a flowchart of scaling control.

FIG. 4 is an explanatory diagram of scaling control.

FIG. 5 is an explanatory diagram of magnification restriction.

[Explanation of symbols]

11...Input memory 12...Display memory 12a...display area 12b... Hidden area (work area) 13...Magnification conversion section 14...Image processing section

Claims (1)

[Claims] 1. An image scaling method for an image drawing device, which stores an image in an input memory, multiplies the image by S, writes it in a display area of a display memory in units of n pixels, and reads the image from the display area and displays it. In , it is determined whether the number of pixels obtained by multiplying the number of pixels in a predetermined direction of the image stored in the input memory by S is an integer multiple of n, and if it is not an integer multiple of n, when multiplied by S, it becomes an integer multiple of n. The image is divided into the first sub-image with the largest size and the remaining second sub-image, the first sub-image is multiplied by S and written in the display area of the display memory in units of n pixels, and the second By adding a dummy image to the sub-image, the second sub-image and the dummy image are multiplied by S, and the non-display area of the display memory is multiplied by S. 1. An image scaling method for an image drawing device, characterized in that an image obtained by multiplying a second sub-image written in a non-display area by S is written at a corresponding position in a display area.