GB2330287A - Background matching for graphics objects - Google Patents
Background matching for graphics objects Download PDFInfo
- Publication number
- GB2330287A GB2330287A GB9721701A GB9721701A GB2330287A GB 2330287 A GB2330287 A GB 2330287A GB 9721701 A GB9721701 A GB 9721701A GB 9721701 A GB9721701 A GB 9721701A GB 2330287 A GB2330287 A GB 2330287A
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- United Kingdom
- Prior art keywords
- image object
- background
- master image
- background area
- area
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T11/00—2D [Two Dimensional] image generation
- G06T11/001—Texturing; Colouring; Generation of texture or colour
Abstract
In a computer graphics system (11) in which image objects (8) derived from master image objects (2) are displayed over a background (4), the master image objects (2) are rendered, such as by anti-aliasing to make the boundary (6) between the image object (8) and the background less visible. When the background (4) is changed, then the objects require re-creating. Together with the rendered image object data, a copy of the master file data (38, 42) together with any rendering parameters (34) for controlling the rendering process is stored. Accordingly, when the background is changed, rendered image objects that require a corresponding change are identified and then the master image data and rendering parameters access to carry out the necessary changes without user intervention.
Description
BACKGROUND MATCHING FOR GRAPHICS OBJECTS
This invention relates to graphics display systems. More particularly, this invention relates to such systems operating with display specifying data that includes areas of graphics with a user defined background appearance and over which graphics objects are displayed.
An example of such a system is an internet web page for which a user can specify a background over which graphics objects, such as buttons, can be displayed.
In order to enhance the appearance of such arrangements, it is known, for example, to perforrn anti-aliasing of a graphic object to produce a rendered image object in which the border between rendered image object and the background is made less visible.
An analogous situation is when the image object to be displayed over the background itself includes a background portion. An example of such an object would be a GIF image or JPEG image having a non-transparent background portion. Where it is required that the background of the GIF or JPEG blends into the web page background so as to make it appear there is no obvious join or border between the GIF or JPEG background and the web page background, then the background portion then needs to be changed to match the background of the web page.
Using the above anti-aliasing techniques and background portion matching, a skilled web page designer is able to produce high quality results. A problem that occurs with the above systems is when the web page designer decides to change the appearance of the background over which the rendered image objects are being displayed. As part of the initial design, or a redesign, the background appearance may be changed several times. In order to properly assess what the final changed result will look like, it then becomes necessary to re-create all of the image objects that were previously rendered over a different background in order that they now match the new background. This is a lengthy, skilled and time consuming operation.
Viewed from one aspect the present invention provides a method of generating display specifying data including data defining an area of graphics for display on a display device, said method comprising the steps of:
selecting at least one background area for display within said area of graphics, said background area having at least one user defined background appearance parameter;
selecting at least one master image object for display over said background area within said area of graphics;
rendering said master image object against said background area to generate a rendered image object modified from said master image object in dependence upon said user defined background appearance parameter so as to make a boundary between said rendered image object and said background area less visible when displayed on said display device; and
storing data defining said background area, said user defined background appearance parameter, said rendered image object and said master image object within said display specifying data; wherein
in response to a change in said user defined background appearance parameter to a changed user defined background appearance parameter:
(i) identifying within said display specifying data any rendered image objects
overlying said background area;
(ii) identifying a master image object for an overlying rendered image object;
and
(iii) rendering said master image object against said background area to
generate a changed rendered image object modified from said master image
object in dependence upon said changed user defined background appearance
parameter so as to make a boundary between said changed rendered image
object and said background area less visible when displayed on said display
device.
The present invention overcomes the above problem by storing the master image object (i.e. unrendered image object) as well as the rendered image object within the display specifying data. Accordingly, when the background is changed, the master image object is available and a search can be made for rendered image objects that are affected by the changed background and then those image objects rerendered using stored master image object and the new background so as to again make the boundary between the two less visible. The invention changes the task of altering the background appearance from one that might typically take several hours with the prior art systems into one that can be accomplished in only a few seconds or minutes and one that can be accomplished by users with no graphics design experience or no expertise in the use of graphics design tools.
The rendering of the image objects over the background can take several different forms. However, a particularly useful form of rendering that can benefit from the present invention is one in which step of rendering includes anti-aliasing said master image object against said background area.
An alternative situation in which the present invention may be used is one in which said master image object includes a background portion and said step of rendering modifies said background portion to match said background area.
An example of a master image object with a background portion needing to be modified would be a JPEG or GIF image with a non-transparent background, such as a round button within a rectangular image.
The rendering undertaken to make the boundary between the rendered image object and the background less visible is itself a process that is subject to user specifiable parameters. The user (graphics designer) will typically adjust these parameters to improve the quality of the final result or to ensure the image data is as small as possible, e.g. by specifying the colour reduction method of a GIF or the quality setting of a JPEG image. In this circumstance it is desirable to provide embodiments in which said steps of rendering are dependent upon at least one rendering parameter, said step of storing stores said rendering parameter, and said step of identifying identifies said rendering parameter for use in generating said changed rendered image object.
In this way, the rendering parameters specified by a user for an object are also stored within the display specifying data and thus may be reapplied when that same object is to be re-rendered due to a background change. This improves the quality of the final result without requiring the parameters to be re-specified.
Whilst it will be appreciated that the rendered image object may take a number of forms, the present invention is particularly suited to embodiments in which said rendered image object and said changed rendered image object are one of a GIF image or a JPEG image.
The display specifying data could take many forms, but the invention is particularly suited to embodiments in which said display specifying data include an xml file or a html file.
Such an html file includes text data and references to image objects to be used on a web page. The image objects are downloaded separately but are then displayed over the same background as the text. The image objects are typically rendered against the background and so when the background changes the image objects need to be changed. At least preferred embodiments of the invention allow a web page authoring tool to be provided that can generate the necessary html file and associated image objects in a manner such that if the background is changed, the html file can be searched for influenced image objects and then those image objects re-rendered with reference to their master copies.
Systems for conveniently generating display specifying data with which the present invention is concerned also advantageously include a library set of master image objects.
The rendering parameters referred to above using which a user may fine-tune the rendering being performed advantageously include data specifying at least one of number of colours used, a transparent background portion flag, an interlaced or noninterlaced flag, a dithering technique and a compression setting.
Viewed from another aspect the present invention provides data processing apparatus for generating display specifying data including data defining an area of graphics for display on a display device, said apparatus comprising:
a background selector for selecting at least one background area for display within said area of graphics, said background area having at least one user defined background appearance parameter;
a master image selector for selecting at least one master image object for display over said background area within said area of graphics;
a renderer for rendering said master image object against said background area to generate a rendered image object modified from said master image object in dependence upon said user defined background appearance parameter so as to make a boundary between said rendered image object and said background area less visible when displayed on said display device; and
a storage device for storing data defining said background area, said user defined background appearance parameter, said rendered image object and said master image object within said display specifying data; wherein
in response to a change in said user defined background appearance parameter to a changed user defined background appearance parameter, said renderer:
(i) identifies within said display specifying data any rendered image objects
overlying said background area;
(ii) identifies a master image object for an overlying rendered image object;
and
(iii) renders said master image object against said background area to generate
a changed rendered image object modified from said master image object in
dependence upon said changed user defined background appearance parameter
so as to make a boundary between said changed rendered image object and
said background area less visible when displayed on said display device.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 schematically illustrates anti-aliasing over a changing background;
Figure 2 schematically illustrates image object having a background portion that needs to be matched to an overall background;
Figure 3 illustrates a computer using which the present invention may be embodied;
Figure 4 illustrates the relationship between rendered images and master images; and
Figure 5 is a flow diagram illustrating the re-rendering process.
Figure 1 shows an object that requires anti-aliasing against a background.
Anti-aliasing is a known technique used to make the boundary between objects or an object in a background less visible and in particular removing the jagged edge produced by pixels imperfectly following a curve. Anti-aliasing computer programs for rendering an object over a background can be found in commercial graphics and publishing software packages.
Moving from left to right in Figure 1, the first graph shows the variation of intensity with position for an object that has not be anti-aliased. The effect this produces on a 2-D object is that a jagged edge between the object and the background.
The next graph shows a smoothed transition between the object and the background that is typically produced with anti-aliasing algorithm. Such anti-aliasing produces a visually much more acceptable result.
The next graph shows the effect when the background is changed for an image that has been anti-aliased to a different background. In this case, a jagged edge reappears around the object. The appearance may actually be worse than if the object was simply in the form of the master image.
The final graph indicates the result when the object is re-rendered against the changed background. This again produces a more acceptable visual appearance.
Figure 2 illustrates another situation in which a master image object 2 must be rendered against a background area 4 in order to make the boundary 6 between the image object and the background area 4 less visible. The master image object in this case is a rectangular GIF file with a non-transparent background, or a JPEG image containing a round button object that is desired to be rendered over the background area 4. The rendered image object 8 is achieved by matching the background portion of the master image object 2 to the appearance of the background area 4. If the appearance of the background area 4 is then changed, the boundary 10 between the rendered image object and the background area again becomes highly visible. This is overcome by re-rendering the image object against the changed background area 4 to produce a changed rendered image object 12.
A further example of the use of the invention is the case in which a GIF with a transparent background overlies a background area that changes. In this case the change in background will automatically show through the background portion of the
GIF, but the non-transparent portion of the GIF will not be anti-aliased correctly for the new background. In this case, the system references the master image object and recreates a new image object with the non-transparent portion anti-aliased against the new background.
Figure 3 illustrates a computer 11, such as a personal computer which can be used to implement the present invention. It will be appreciated that alternative arrangements such as client/server would be possible, e.g. a server computer on the internet storing all the image data and controlled and managed by a web-browser client.
In this example, the computer 11 includes a central processing unit 13, a random access memory 14, a hard disc storage device 16, a disc controller 18, a modem 20 for connection to a telephone line 22, a display monitor 24, a display driver 26, a loud speaker 28 and a sound card 30. The user can input data and commands to the computer 11 via the keyboard 32 or the mouse 34.
A computer 11 such as that illustrated operates by executing program files stored on the disc storage device 16 to manipulate data corresponding to the display specifying data referred to above and then using this, for example, to drive the display monitor 24 via the display driver 26. The display specifying data is stored within the disc storage device 16 or temporarily within the random access memory 14.
Data to be manipulated, or program files for manipulating data, could also be downloaded from the internet via the modem 20. It would also be possible for the computer 11 to act as a client connected to a server computer (not shown) that would in fact perform the manipulation of the display specifying data and would store the display specifying data. This server could also be host for the web site being generated.
Figure 4 shows the stored data mapping the relationship between rendered images and master images. Data is specified identifying each rendered image 32.
Associated with each rendered image is rendering information 34 and a pointer 36 to a master file 38. The rendering information specifies parameters used by the rendering algorithms to generate those rendered images such as a number of colours used, a transparent background portion flag, an interlaced or non-interlaced flag and a dithering technique specifier.
It will be seen that more than one rendered image 40 can in fact be generated from a single master image 42. In this case only a single copy of the master image file need be stored. The rendering parameters for each rendered image can be different.
Figure 5 is a flow diagram illustrating the re-rendering process. At step 44 a user specifies a change in the background colour of a web page. At step 46, the computer 11 searches for the html file corresponding to the changed page or pages.
At step 48, the computer searches for image statements or end of file markers. At stage 50, if an end of file marker is found, then the process terminates. If image statements are found, rather than an end of file marker, then reference is made to the data illustrated in Figure 4 at step 52 of Figure 5. If the image object found is included within this data, then the master file for that image object is identified at step 54. The rendering information for that image object is also recovered at step 56.
The master file, the rendering information and the new background are then passed to a rendering system at step 58. The rendering system can be in the form of an antialiasing algorithm of one of the known types or an algorithm that changes the background portion of the image object to match the new background area. This rerendering takes place at step 60. The processing them returns to scan for the next image statement or the end of file statement.
It will be appreciated that the example algorithm described with reference to
Figure 3 is just one example of an algorithm that can implement the invention, e.g. rather than scanning the html file for the effected images, a table pointing to all the effected images could be used.
Claims (11)
- CLAIMS 1. A method of generating display specifying data including data defining an area of graphics for display on a display device, said method comprising the steps of: selecting at least one background area for display within said area of graphics, said background area having at least one user defined background appearance parameter; selecting at least one master image object for display over said background area within said area of graphics; rendering said master image object against said background area to generate a rendered image object modified from said master image object in dependence upon said user defined background appearance parameter so as to make a boundary between said rendered image object and said background area less visible when displayed on said display device; and storing data defining said background area, said user defined background appearance parameter, said rendered image object and said master image object within said display specifying data; wherein in response to a change in said user defined background appearance parameter to a changed user defined background appearance parameter: (i) identifying within said display specifying data any rendered image objects overlying said background area; (ii) identifying a master image object for an overlying rendered image object; and (iii) rendering said master image object against said background area to generate a changed rendered image object modified from said master image object in dependence upon said changed user defined background appearance parameter so as to make a boundary between said changed rendered image object and said background area less visible when displayed on said display device.
- 2. A method of generating display specifying data as claimed in claim 1, wherein said step of rendering includes anti-aliasing said master image object against said background area.
- 3. A method of generating display specifying data as claimed in any one of claims 1 and 2, wherein said master image object includes a background portion and said step of rendering modifies said background portion to match said background area.
- 4. A method of generating display specifying data as claimed in any one of claims 1, 2 and 3, wherein said steps of rendering are dependent upon at least one rendering parameter, said step of storing stores said rendering parameter, and said step of identifying identifies said rendering parameter for use in generating said changed rendered image object.
- 5. A method of generating display specifying data as claimed in any one of the preceding claims, wherein said rendered image object and said changed rendered image object are one of a GIF image or a JPEG image.
- 6. A method of generating display specifying data as claimed in any one of the preceding claims, wherein said display specifying data include an xml file or a html file.
- 7. A method of generating display specifying data as claimed in any one of the preceding claims, wherein said master image object is selected from a library set of master image objects.
- 8. A method of generating display specifying data as claimed in claim 4, wherein said at least one rendering parameter includes data specifying at least one of number of colours used, a transparent background portion flag, an interlaced or non-interlaced flag, a dithering technique and a compression setting.
- 9. A data processing apparatus for generating display specifying data including data defining an area of graphics for display on a display device, said apparatus comprising: a background selector for selecting at least one background area for display within said area of graphics, said background area having at least one user defined background appearance parameter; a master image selector for selecting at least one master image object for display over said background area within said area of graphics; a renderer for rendering said master image object against said background area to generate a rendered image object modified from said master image object in dependence upon said user defined background appearance parameter so as to make a boundary between said rendered image object and said background area less visible when displayed on said display device; and a storage device for storing data defining said background area, said user defined background appearance parameter, said rendered image object and said master image object within said display specifying data; wherein in response to a change in said user defined background appearance parameter to a changed user defined background appearance parameter, said renderer: (i) identifies within said display specifying data any rendered image objects overlying said background area; (ii) identifies a master image object for an overlying rendered image object; and (iii) renders said master image object against said background area to generate a changed rendered image object modified from said master image object in dependence upon said changed user defined background appearance parameter so as to make a boundary between said changed rendered image object and said background area less visible when displayed on said display device.
- 10. A method of generating display specifying substantially as hereinbefore described with reference to the accompanying drawings.
- 11. A data processing apparatus for generating display specifying data substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9721701A GB2330287B (en) | 1997-10-13 | 1997-10-13 | Background matching for graphics objects |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9721701A GB2330287B (en) | 1997-10-13 | 1997-10-13 | Background matching for graphics objects |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9721701D0 GB9721701D0 (en) | 1997-12-10 |
| GB2330287A true GB2330287A (en) | 1999-04-14 |
| GB2330287B GB2330287B (en) | 2002-03-20 |
Family
ID=10820488
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9721701A Expired - Fee Related GB2330287B (en) | 1997-10-13 | 1997-10-13 | Background matching for graphics objects |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2330287B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1248250A1 (en) * | 2001-04-04 | 2002-10-09 | Sun Microsystems, Inc. | Optimized data access for drawing operations |
-
1997
- 1997-10-13 GB GB9721701A patent/GB2330287B/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1248250A1 (en) * | 2001-04-04 | 2002-10-09 | Sun Microsystems, Inc. | Optimized data access for drawing operations |
| US7463271B2 (en) | 2001-04-04 | 2008-12-09 | Sun Microsystems, Inc. | Optimized access for drawing operations |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9721701D0 (en) | 1997-12-10 |
| GB2330287B (en) | 2002-03-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20021013 |