GB2243061A

GB2243061A - Image creation system

Info

Publication number: GB2243061A
Application number: GB9008272A
Authority: GB
Inventors: Peter Evans
Original assignee: AFE DISPLAYS Ltd
Current assignee: AFE DISPLAYS Ltd
Priority date: 1990-04-11
Filing date: 1990-04-11
Publication date: 1991-10-16
Anticipated expiration: 2010-04-11
Also published as: GB9008272D0; GB2243061B

Abstract

An image creation for creating a smoothed image made up of a plurality of lines and columns of pixels, comprises a processor (10) responsive to a signal from an upstream CPU (11) to write into a first mapped memory (12) pixel information relating to an image (I), each pixel in the first memory (12) being processed together with adjacent pixels in either the line (14-17) or column (20-24) direction to produce a modified pixel which is stored in a second mapped memory (30) the processing of each modified pixel and the adjacent pixels being repeated but in either the column (20'-24') or line (14'-17') direction respectively, to produce a further modified pixel. The second mapped memory contains a row and column smoothed version (Fig 5) of the input image (Fig 2). <IMAGE>

Description

Title: "Image creation system" Descri#tion of Invention This invention relates to a method of operating an image creation system.

A technique known as "antialiasing" is known for improving the appearance of an image such as a straight line on a screen such as a visual display unit (VDU) which presents the image as a plurality of lines and columns of pixels.

In one such method, when a processor writes onto the screen image information from a memory, the processor performs calculations so that pixels adjacent pixels through which the straight line passes, are "coloured in" to a degree depending on how far from the actual line the adjacent pixel is, and then "fills in" the adjacent pixels as appropriate.

In another known method, each pixel point of information in the memory means is considered in turn along with each of its surrounding pixels in both surrounding lines and columns, to achieve an average value which is then displayed on the screen.

According to the invention we provide a method of operating an image creation system for creating an image made up of a plurality of lines and columns of pixels, the system comprising processor means responsive to a signal from an upstream central processing unit (CPU) to write into a first memory means information relating to an image, the image information being stored in the first memory means as a plurality of pixel points of information, each having a corresponding line and column pixel position in the image to be displayed on a screen, the method comprising the steps of processing each pixel point of information in the first memory means together with pixel points of information relating to adjacent pixels in either the line or column of pixels of the image to produce modified information relating to the image, storing the modified information in a second memory means as a plurality of pixel points of modified information each having a corresponding line and column position in the image and processing each pixel point of modified information in the second memory means together with pixel points of modified information relating to adjacent pixels in either the column or line of pixels of the image respectively, to produce further modified information relating to the image.

In a preferred embodiment, each pixel point of information in the first memory means is processed together with the pixel points of information relating to the pixels on either side in the line of the image containing the corresponding pixel to produce the modified information and each pixel point of modified information in the second memory means is processed together with the pixel points of modified information relating to the pixels on either side in the column of the image containing the corresponding pixel to produce the further modified information.

The further modified information may be used to display a representation of the original image on the screen such as a VDU where the image is displayed by a set matrix of lines and columns of pixels.

Using the method of the present invention, antialiasing can be achieved much faster than with known methods.

For a monochrome image creation system each pixel point of information in the first memory means may comprise a luminescence value. The processing means may average the luminescence value of each pixel point of information with the luminescence values of the pixel points of information corresponding to next adjacent pixels to it in the line or column of the image to produce a modified luminescence value which is stored in the second memory means, and the processing means may then average the modified luminescence value of each pixel point of modified information in the second memory means with the luminescence values of the pixels points of modified information correspond to next adjacent pixels to it in the column or line respectively, to produce a further modified luminescence value for each pixel point.

For a colour image creation system where each pixel point of information in the first memory means comprises bits of information relating to at least red, green and blue colour information, the processing means may be arranged to average the individual bits of information with the corresponding bits of information of the next adjacent pixels in the respective line or column of the image to produce modified values of the bits of information which are stored in the second memory means as pixel points of modified information and the processing means may then average the individual modified bits of information of each pixel point of modified information with the corresponding bits of information of the next adjacent pixels in the respective column or line of the image to produce further modified values of the individual bits of information.

The invention will now be described with reference to the accompanying diagrams in which FIGURE 1 is a diagram illustrating an image creation system which can be operated in accordance with the invention, FIGURE 2 is a diagram of part of a screen displaying an image without antialiasing.

FIGURE 3 is a diagrammatic representation of part of a first memory means storing pixel point information, FIGURE 4 is a view similar to figure 3 but of a second memory means containing pixel points of modified information and, FIGURE 5 is a diagram of part of a screen on which is displayed an image created by a method in accordance with the invention.

Referring to the drawings, an image creation system comprises a processing means 10 which is arranged to receive a signal from an upstream CPU 11. The processor 10 then writes into a first memory means 12 information relating to an image which is contained in the input signal from the CPU 11, and which may later, be displayed in a modified form on a screen 13.

A practical screen such as a VDU would display the image as a set matrix of lines and columns of pixels. In an example, a screen would have up to 900 lines of pixels or more, arranged in e,g. 512 columns.

As shown, the input signal comprises information to enable a straight thin line image I to be displayed.

However, it will be appreciated that if this information were fed from the memory 12 direct to the screen 13, a clear image would not be produced because of the nature of the screen 12 which can only display an image as a defined matrix of pixels arranged in lines and columns so that at best, a simple black line would appear unclear, e.g. as indicated in figure 2 which shows only 144 pixels of the entire screen 13, which in the example described, could contain about 460,800 pixels.

For a colour imaging system, the image would be even more unclear.

Systems are known which seek to improve the appearance of the image on the screen by a technique known as antialiasing.

The system in accordance with the invention is operated using a second, temporary, memory means 30, which is provided to enable the processor 10 to process the information in the first memory 12 without obliterating the information in memory means 12, to enable a representation of the image line I to be displayed on the screen 13.

Referring to figure 3, it can be seen that the memory 12 can be represented as a plurality of lines 1417 and columns 20-24 which define a plurality of pixel points into which information can be written by the processor 10, each pixel point having a corresponding pixel in the image to be created. In the method in accordance with the invention, each pixel point of information is subsequently processed by the processor 10 to provide modified information which is then temporarily stored in the second memory means 30.

By way of example, for a monochrome system, each pixel point in memory 12 would contain a luminescence value which would be information to enable the screen 13 to display the corresponding pixels as a degree of blackness.

The processor 10 will average the luminescence of each pixel point within memory 12, with the luminescence values of the adjacent pixel points to either side in the same line.

In the example illustrated, the luminescence value of pixel point at line 15 column 22, will be averaged with the luminescence values of the pixel points in line 15 in columns 21 and 23 which correspond to the next adjacent pixels in the same line of the image. The modified luminescence value relating to the pixel point at line 15 column 22, will then be temporarily stored in the second memory means 30, preferably at a corresponding line and column position e.g. as indicated at position 15',22' indicated in figure 4.

When all of the pixel points of memory 13 have been thus processed and the corresponding pixel points of memory means 30 contain the modified information for all the pixel points, the processor 10 can then further process the pixel points of modified information of memory 30.

Considering the pixel point indicated at line 15' column 22', the modified luminescence value of the pixel point will be averaged with the modified luminescence values of the next adjacent pixel points in column 22', at lines 14' and 16' which correspond to the next adjacent pixels in the same column of the image to achieve a further modified luminescence value. This further modified luminescence value may be fed directly to screen 13, or stored in a still further memory, or otherwise further processed as desired.

This is repeated for all the pixel points of modified information in memory 30 and the result for image line I will be as indicated in figure 5. It will be noted that the outer pixels are not included because information is not available for the pixels in the lines and columns beyond the 144 pixel storage sites considered by way of example.

For a colour imaging system, each pixel point will contain individual bits of information relating to red, green, and blue colour information at least. In this event, the processor 10 may average the red bit information of every pixel point in memory 12 with the red bit information of the adjacent pixel points corresponding to adjacent pixels of the image in the same line to achieve modified red pixel point information for storing in memory 30, preferably at a corresponding line and column position, to the pixel point in memory 12, and similarly, for the green and blue colours, and any other information stored at each pixel point in memory 12.

Further, processor 10 may process the modified information in memory 30 by averaging the red bit information of each pixel point of modified information with the red bit information of the next adjacent pixel points of information corresponding to adjacent pixels in the same column of the image, to produce further modified information relating to the red bit information, in each pixel point position, and similarly for the modified green and blue colour information, and any other information stored in the memory 30.

Various modifications may be made without departing from the scope of the invention.

In the example described, the processor 10 first processes the pixel points of memory 12 by averaging luminescence value/colour or other bit information in the pixel point with the same information contained in adjacent pixel points of information corresponding to adjacent pixels in the same line of the image. If desired, the processor 10 may first average or otherwise process the pixel point information of memory 12 with regard to pixel point information contained in adjacent pixel points corresponding to adjacent pixels in the same column of the image, in which case, the processor 10 may secondly average or otherwise process the modified information in memory 30 for each pixel point together with the pixel points of modified information in adjacent pixel points corresponding to adjacent pixels in the same line rather than in the same column of the image.

In each case, the speed by which the antialiasing technique can be employed, is improved compared with previous methods.

The features disclosed in the foregoing description or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A method of operating an image creation system for creating an image made up of a plurality of lines and columns of pixels, the system comprising processor means responsive to a signal from an upstream central processing unit (CPU) to write into a first memory means information relating to an image, the image information being stored in the first memory means as a plurality of pixel points of information, each having a corresponding line and column pixel position in the image to be displayed on a screen, the method comprising the steps of processing each pixel point of information in the first memory means together with pixel points of information relating to adjacent pixels in either the line or column of pixels of the image to produce modified information relating to the image, storing the modified information in a second memory means as a plurality of pixel points of modified information each having a corresponding line and column position in the image and processing each pixel point of modified information in the second memory means together with pixel points of modified information relating to adjacent pixels in either the column or line of pixels of the image respectively, to produce further modified information relating to the image.

2. A method according to claim 1 wherein each pixel point of information in the first memory means is processed together with the pixel points of information relating to the pixels on either side in the line of the image containing the corresponding pixel to produce the modified information and each pixel point of modified information in the second memory means is processed together with the pixel points of modified information relating to the pixels on either side in the column of the image containing the corresponding pixel to produce the further modified information.

3. A method according to claim 1 or claim 2 wherein the further modified information is used to display a representation of the original image on the screen.

4. A method according to claim 3 wherein the screen is a VDU where the image is displayed by a set matrix of lines and columns of pixels.

5. A method according to any one of claims 1 to 4 wherein the system is a monochrome image creation system each pixel point of information in the first memory means comprising a luminescence value.

6. A method according to claim 5 wherein the processing means averages the luminescence value of each pixel point of information with the luminescence values of the pixel points of information corresponding to next adjacent pixels to it in the line or column of the image to produce a modified luminescence value which is stored in the second memory means, and the processing means then averages the modified luminescence value of each pixel point of modified information in the second memory means with the luminescence values of the pixels points of modified information correspond to next adjacent pixels to it in the column or line respectively, to produce a further modified luminescence value for each pixel point.

7. A method according to any one of claims 1 to 4 wherein the system is a colour image creation system where each pixel point of information in the first memory means comprises bits of information relating to at least red, green and blue colour information.

8. A method according to claim 7 wherein the processing means is arranged to average the individual bits of information with the corresponding bits of information of the next adjacent pixels in the respective line or column of the image to produce modified values of the bits of information which are stored in the second memory means as pixel points of modified information and the processing means then averaging the individual modified bits of information of each pixel point of modified information with the corresponding bits of information of the next adjacent pixels in the respective column or line of the image to produce further modified values of the individual bits of information.

9. A method of operating an image creation system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

10. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.