System and method for scaling graphic images

• US 5,426,723 A
• Filed: 03/09/1992
• Issued: 06/20/1995
• Est. Priority Date: 03/09/1992
• Status: Expired due to Fees

• Current Assignee: Spacelabs, Inc. (OSI Systems Incorporated)
• Original Assignee: Spacelabs Medical Incorporated (OSI Systems Incorporated)
• Inventors: Horsley, Eric R.
• Primary Examiner(s): JANKUS, ALMIS R
• Application Number:
  US07/848,683
• Time in Patent Office: 1,198 Days
• Field of Search: 395/123-129, 395/133, 395/139, 395/162, 395/164, 358/140
• US Class Current: 345/428
• CPC Class Codes: G06T 3/40 Scaling of whole images or parts thereof, e.g. expanding or contracting

Abstract

A method and system to scale a graphics image from one graphics display resolution to a different graphics display resolution without the need for creating an entire new set of graphics commands. The present invention allows the non-integer scaling of a graphics image and creates an array of virtual pixels that control intensity of the actual pixels within the graphics memory and keep track of the source of intensity contribution for each actual pixel if scaled graphics images overlap an actual pixel. If one of the multiple sources of intensity for a given actual pixel is subsequently erased, the contribution information allows the actual pixel to be erased in a manner that accounts for the direction of the contribution as well as the actual intensity contribution.

Claims

1. A system to scale a graphic image from an existing display having an existing display resolution to a new display having a new display resolution where each display is defined in two components corresponding to vertical and horizontal coordinates of the displays, the system comprising:

means for determining a first old resolution and a second old resolution of the existing display, said first and second old resolutions corresponding to the two components of the existing display;

a graphics memory to store the scaled graphic image, said graphic memory controlling a plurality of pixels on the new display, each of said pixels being defined by a number, N, of intensity control bits that each provide equal control of a total intensity of each of said pixels and provide 1/Nth pixel spatial resolution;

means for determining a first new resolution and a second new resolution of a new display, said first and second new resolutions corresponding to the number, N, of said intensity control bits and the two components of the new display;

scaling means for scaling the graphic image from the existing display resolution to the new display resolution by scaling said first old resolution into said first new resolution and said second old resolution into said second new resolution to generate a scaled graphic image;

a mask for masking at least one of said plurality of pixels to determine an intensity and spatial contribution from each of said intensity control bits; and

means for storing said scaled graphic image in said graphic memory, whereby each pixel in said graphics memory is controlled by said intensity control bits to give intensity control and an appearance of 1/Nth pixel spatial resolution for each pixel.

2. The system of claim 1 wherein said scaling means scales the graphic image by multiplying the first component of the graphic image, expressed in terms of said first old resolution, by said first new resolution and dividing by said first old resolution to determine the first scaled component of the graphic image, expressed in terms of said first new resolution, and by multiplying the second component of the graphic image, expressed in terms of said second old resolution, by said second new resolution and dividing by said second old resolution to determine the second scaled component of the graphic image, expressed in terms of said second new resolution.

3. The system of claim 1, further including storage means for storing precalculated scale factors for each point of the existing display, expressed in terms of said first old resolution and for each point of the existing display, expressed in terms of said second old resolution in a look-up table, whereby said scaling means addresses a storage location in said storage means corresponding to one of said points and reads the contents of said storage location to determine the scaled pixel location on the new graphics display, expressed in terms of said first or said second new resolution.

4. The system of claim 1, further including means for scrolling to move the entire scaled graphics image in one direction corresponding to either the first component or the second component of the new graphics display by shifting the contents of said graphics memory one virtual pixel location in the direction that the graphic image is to be scrolled.

5. The system of claim 1, wherein said means for determining said first new resolution and said second new resolution queries the new display to determine the resolution of the new display in terms of the two components.

6. A system to scale a graphic image from an existing display an existing display resolution to a new display having a new display resolution where each display is defined in two components corresponding to vertical and horizontal coordinates of the displays, the system comprising:

means for determining a first old resolution and a second old resolution of the existing display, said first and second old resolutions corresponding to the two components of the existing display;

a graphics memory to store the scaled graphic image, said graphic memory controlling a plurality of pixels on the new display, each of said pixels being defined by four intensity control bits that each control one-quarter of a total intensity of each of said pixels and provide one-quarter pixel resolution;

means for determining a first new resolution and a second new resolution of a new display, said first and second new resolutions corresponding to the number of said intensity control bits and the two components of the new display;

scaling means for scaling the graphic image from the existing display resolution to the new display resolution by scaling said first old resolution into said first new resolution and said second old resolution into said second new resolution to generate a scaled graphic image;

a mask for masking at least one of said plurality of pixels to determine an intensity and spatial contribution from each of said intensity control bits; and

means for storing said scaled graphic image in said graphic memory, whereby each pixel in said memory is controlled by said intensity control bits to provide intensity control and an appearance of one-quarter pixel spatial resolution for each pixel.

7. The system of claim 6 wherein said scaling means scales the graphic image by multiplying the first component of the graphic image, expressed in terms of said first old resolution, by said first new resolution and dividing by said first old resolution to determine the first scaled component of the graphic image, expressed in terms of said first new resolution, and by multiplying the second component of the graphic image, expressed in terms of said second old resolution, by said second new resolution and dividing by said second old resolution to determine the second scaled component of the graphic image, expressed in terms of said second new resolution.

8. The system of claim 6, further including means for scrolling to move the entire scaled graphics image in one direction corresponding to either the first component or the second component of the new graphics display by shifting the contents of said graphics memory one virtual pixel location in the direction that the graphic image is to be scrolled.

9. The system of claim 6, further including storage means for storing precalculated scale factors for each point of the existing display, expressed in terms of said first old resolution and for each point of the existing display expressed in terms of said second old resolution in a look-up table, whereby said scaling means addresses a storage location in said storage means corresponding to one of said points and reads the contents of said storage location to determine the scaled pixel location on the new graphics display, expressed in terms of said first or said second new resolution.

10. The system of claim 9, wherein said means for determining said first new resolution and said second new resolution queries the new display to determine the resolution of the new display in terms of the two components.

11. A system to scale a graphics image from an existing display having an existing display resolution to a new display having a new display resolution where each display is defined in two components corresponding to vertical and horizontal coordinates of the displays, the system comprising:

a first storage location containing first and second old resolution values defining the existing display resolution of the two components of the existing display;

a second storage location containing first and second new resolution values defining the new display resolution of the two components of the new display;

a graphics input unit containing the graphics image defined in terms of said old resolution values;

a central processor, electrically coupled to said graphics input unit to control the flow of data from said graphics input unit;

a scaler, electrically coupled to said central processor to receive and convert the graphics image from an old resolution corresponding to said old resolution values to a new resolution corresponding to said new resolution values thereby generating a scaled graphic image;

a graphics memory electrically coupled to said central processor to receive said scaled graphic image, said graphics memory controlling a plurality of pixels on the new display, each of said pixels being defined by a number, N, of intensity control bits that each provide equal control of a total intensity of each of said pixels and provide 1/Nth pixel spatial resolution; and

a graphics mask generator, electrically coupled to said central processor and said graphics memory to create mask patterns indicative of an intensity level and spatial resolution of said pixels, whereby each of said pixels in said graphics memory is controlled by said intensity control bits to give intensity control and an appearance of 1/Nth pixel spatial resolution for each pixel.

12. The system of claim 11 wherein said scaler scales the graphic image by multiplying the first component value of each pixel of the existing display of the graphic image, expressed in terms of said first old resolution, by said first new resolution and dividing by said first old resolution to determine the first scaled component value of each of said pixels of the new display of the graphic image, expressed in terms of said first new resolution, and by multiplying the second component value of each pixel of the existing display of the graphic image, expressed in terms of said second old resolution, by said second new resolution and dividing by said second old resolution to determine the second scaled component value of each of said pixels of the new display of the graphic image, expressed in terms of said second new resolution.

13. The system of claim 11 wherein said memory contains a look-up table for storing precalculated scale factors for each point of the existing display, expressed in terms of said first old resolution and for each point of the existing display, expressed in terms of said second old resolution, whereby said scaler addresses a storage location in said look-up table corresponding to one of said points and reads the contents of said storage location to determine the scaled pixel location on the new graphics display, expressed in terms of said first or said second new resolution.

14. A method for scaling a graphic image from an existing display having an existing display resolution to a new display having a new display resolution where each display is defined in two components corresponding to vertical and horizontal coordinates of the displays, the method comprising the steps of:

(a) determining a first old resolution value of the existing display, said first old resolution value corresponding to a first one of the two components of the existing display;

(b) determining a second old resolution value of the existing display, said second old resolution value corresponding to a second one of the two components of the existing display;

(c) determining a first new resolution value of the new display, said first new resolution value corresponding to a number of intensity control bits for each of a plurality of pixels in a graphics memory and a first one of the two components of the new display;

(d) determining a second new resolution value of the new display, said second new resolution value corresponding to said number of intensity control bits and a second one of the two components of the new display;

(e) scaling the graphic image from an old resolution corresponding to said first and second old resolution values to a new resolution corresponding to said first and second new resolution values, thereby generating a scaled graphic image;

(f) masking said scaled graphic image to determine an intensity and spatial contribution from the graphic image for each of said plurality of pixels; and

(g) storing said scaled graphic image in said graphics memory containing said number of intensity control bits for each of said plurality of pixels, whereby each pixel in said graphics memory is controlled by said intensity control bits to provide intensity control and create the appearance of spatial control for each pixel.

15. The method of claim 14, further including the steps of precalculating and storing scale factors for each point of the existing display, expressed in terms of said first old resolution value and for each point of the existing display, expressed in terms of said second old resolution value in a look-up table, whereby said step of scaling is accomplished by addressing a storage location in said look-up table corresponding to one of said points and reads the contents of said look-up table to determine the scaled pixel location on the new display, expressed in terms of said first or said second new resolution values.

16. The method of claim 14 wherein said step of scaling further includes the steps of:

calculating first and second coordinates for each of the corners of an unscaled graphic rectangle that represents a portion of an unscaled graphic image, said first and second coordinates corresponding to said first and second components expressed in terms of said first and said second old resolution values;

scaling from said first old resolution value to said first new resolution value by multiplying said first coordinate by said first new resolution value and dividing by said first old resolution value for each corner of said unscaled rectangle; and

scaling from said second old resolution value to said second new resolution value by multiplying said second coordinate by said second new resolution value and dividing by said second old resolution value for each corner of said unscaled rectangle.

17. The method of claim 16 wherein the steps of calculating coordinates and scaling said first and second old resolutions to said first and second resolutions further includes the steps of calculating said first and second coordinates for opposite corners of said unscaled rectangle and scales said first and second old resolutions to said first and second new resolutions only for said opposite corners of said unscaled rectangle.

18. A method for scaling a graphic image from an existing display having an existing display resolution to a new display having a new display resolution where each display is defined in two components corresponding to vertical and horizontal coordinates of the displays, the method comprising the steps of:

(a) determining a first old resolution of the existing display, said first old resolution corresponding to a first one of the two components of the existing display;

(b) determining a second old resolution of the existing display, said second old resolution corresponding to a second one of the two components of the existing display;

(c) determining a first new resolution of the new display, said first new resolution corresponding to four intensity control bits for each of a plurality of pixels in a graphics memory and a first one of the two components of the new display;

(d) determining a second new resolution of the new display, said second new resolution corresponding to said four intensity control bits and a second one of the two components of the new display;

(e) calculating first and second coordinates for each corner of an unscaled graphic rectangle that represents a portion of an unscaled graphic image, said first and second coordinates corresponding to said first and second components expressed in terms of said first and said second old resolutions;

(f) scaling from said first old resolution to said first new resolution by multiplying said first coordinate by said first new resolution and dividing by said first old resolution for each of said corners of said unscaled rectangle;

(g) scaling from said second old resolution to said second new resolution by multiplying said second coordinate by said second new resolution and dividing by said second old resolution for each of said corners of said unscaled rectangle thereby generating a scaled graphic image;

(h) masking said scaled graphic image to determine an intensity contribution from each of said intensity control bits; and

(i) storing said scaled graphic image in said graphics memory containing said number of intensity control bit for each of said plurality of pixels, whereby each pixel in said graphics memory is controlled by said intensity control bits to provide intensity control and create the appearance of spatial control for each pixel.

19. The method of claim 18 wherein the steps e-g of calculating coordinates and scaling said first and second old resolutions to said first and second resolutions further includes the steps of calculating said first and second coordinates for opposite corners of said unsealed rectangle and scales said first and second old resolutions to said first and second new resolutions only for said opposite corners of said unsealed rectangle.

20. The method of claim 18, further including the steps of precalculating and storing scale factors for each point of the existing display, expressed in terms of said first old resolution and for each point of the existing display, expressed in terms of said second old resolution in a look-up table, whereby said steps f-g of scaling is accomplished by addressing a storage location in said look-up table corresponding to one of said points and reads the contents of said look-up table to determine the scaled pixel location on the new graphics display, expressed in terms of said first or said second new resolution.