Techniques for displaying complex characters
First Claim
Patent Images
1. A method for rendering an image of a complex character for display on a monitor, wherein the image is formed of a plurality of pixels arranged in rows and columns and is represented by a raw character bitmap, comprising:
- filtering the raw character bitmap to form a filtered character bitmap performing a first type scaling operation on the filtered bitmap to form a first scaled bitmap;
determining a scalefactor based upon the first scaled bitmap and a target bitmap, wherein the target bitmap is suitable for storage in a memory device coupled to the monitor; and
further recursively scaling the first scaled bitmap using a second type scaling operation to form the target bitmap based upon the scalefactor.
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Abstract
Systems and methods for rendering a complex character suitable for display on a monitor are provided. A raw character bitmap representing the complex character is filtered to form a filtered bitmap so as to reduce the effects of monitor flicker and enhance image contrast. The filtered bitmap is then scaled down to a target bitmap using a bilinear scaling operation followed by recursive cubic scaling operations. The target bitmap is suitably sized for storage in a memory device coupled to the monitor.
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Citations
20 Claims
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1. A method for rendering an image of a complex character for display on a monitor, wherein the image is formed of a plurality of pixels arranged in rows and columns and is represented by a raw character bitmap, comprising:
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filtering the raw character bitmap to form a filtered character bitmap performing a first type scaling operation on the filtered bitmap to form a first scaled bitmap;
determining a scalefactor based upon the first scaled bitmap and a target bitmap, wherein the target bitmap is suitable for storage in a memory device coupled to the monitor; and
further recursively scaling the first scaled bitmap using a second type scaling operation to form the target bitmap based upon the scalefactor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
multiplying the raw bitmap with a gaussian filter having a gaussian kernal to form a multiplied bitmap; and
dividing the multiplied bitmap by a reduced kernal divisor to form the filtered bitmap, wherein the dividing by the reduced divisor increases the contrast between the darkest pixel and the brightest pixel of the filtered bitmap.
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5. A method as recited in claim 4, wherein the reduced kernal divisor is the sum of the kernal reduced by a contrast enhancement factor, wherein the sum of the kernal is the summation of the elements of the kernal.
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6. A method as recited in claim 5, wherein the kernal is a 5×
- 5 gaussian kernal.
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7. A method as recited in claim 1, wherein the monitor is coupled to a television system suitable for receiving television signals.
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8. A method as recited in claim 7, wherein the television system is coupled to a set top box arranged to retrieve a requested document from a host computer, wherein the requested document includes the raw character bitmap.
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9. A method as recited in claim 8, wherein the set top box includes a cache memory suitable for storing the target bitmap.
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10. A method as recited in claim 9, wherein the cache memory is a Read Only Memory device arranged to store a plurality of provided target bitmaps each corresponding to a particular complex character.
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11. An apparatus for rendering an image of a complex character for display on a monitor, wherein the image is formed of a plurality of pixels arranged in rows and columns, and wherein the complex character is represented by a raw character bitmap, comprising:
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a filtering unit that receives the raw character bitmap and performs a selected filtering operation to form a filtered character bitmap;
a decimator unit coupled to the filtering unit that receives the filtered character bitmap and performs a series of multiple type scaling operations on the received filtered character bitmap to form a target bitmap, wherein the target bitmap is representative of a selected font size corresponding to the displayed image; and
a memory device coupled to the decimator unit arranged to store the target bitmap, wherein when a complex character corresponding to a selected one of the target bitmaps is to be displayed on the television monitor, the selected bitmap is passed to a frame buffer unit coupled to cache memory device. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
multiplying the raw character bitmap with a gaussian filter having a kernal to form a multiplied bitmap; and
dividing the multiplied bitmap by a reduced kernal divisor to form the filtered bitmap such that the contrast between the darkest pixel and the brightest pixel of the filtered bitmap is enhanced.
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13. A method as recited in claim 12, wherein the reduced kernal divisor is the sum of the kernal reduced by a contrast enhancement factor, wherein the sum of the kernal is the summation of the elements of the kernal.
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14. A method as recited in claim 13, wherein the kernal is a 5×
- 5 gaussian kernal.
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15. An apparatus as recited in claim 11, wherein the performs a series of multiple type scaling operations on the received filtered character bitmap to form a target bitmap comprises:
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performing a first type scaling operation on the filtered character bitmap to form a first scaled character bitmap;
determining a scalefactor based upon the first scaled character bitmap and the target bitmap; and
further recursively scaling the first scaled bitmap using a second type scaling operation to form the target bitmap, wherein the recursion is based upon the scalefactor.
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16. An apparatus as recited in claim 15, wherein the first type scaling operation is a bilinear scaling operation and wherein the second type scaling operation is a cubic scaling operation.
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17. An apparatus as recited in claim 16, wherein the apparatus is a set top box coupled to a television arranged to retrieve a selected document from a host computer connected thereto.
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18. An apparatus as recited in claim 17, wherein the host computer is part of a computer network.
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19. An apparatus as recited in claim 18, wherein the computer network is the Internet and the requested document is an HTML document.
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20. A set top box as recited in claim 11, wherein the memory device is a Read Only Memory device arranged to store the target bitmaps corresponding to the complex characters.
Specification