Compression method for aviation weather products
First Claim
1. A method for compressing graphical image data comprising a plurality of pixels for display, wherein the pixels comprise background pixels for depicting the image background and data pixels having at least one different color than the background pixels for conveying information based on the data pixel color, said method comprising:
- (a) scanning the pixels line by line;
(b) assigning a first instruction to a plurality of successive pixels depicting the image background, wherein the first instruction indicates the number of successive background pixels; and
(c) assigning a second instruction to a plurality of successive data pixels, wherein the second instruction indicates the number of successive data pixels.
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Abstract
An imagery compression algorithm is disclosed for transmitting imagery data to an aircraft over a relatively narrow bandwidth channel. The imagery data is first trimmed to include only images required by the aircraft during flight. The image is also de-cluttered by removing geographical boundary lines and isolated pixels that likely do not represent relevant weather imagery data. The compression scheme provides a plurality of instructions for compressing the image data. The first instruction depicts the number of multiple image lines that contain no imagery data, i.e., they indicate only the background display color. Two instructions identify short background color segments and long background segments, wherein the division between short and long segments is a predetermined value. Each of the data or color pixels is individually encoded with a fourth instructions characterizing the number of successive data pixels followed by a bit sequence indicating the color of each individual data pixel.
37 Citations
20 Claims
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1. A method for compressing graphical image data comprising a plurality of pixels for display, wherein the pixels comprise background pixels for depicting the image background and data pixels having at least one different color than the background pixels for conveying information based on the data pixel color, said method comprising:
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(a) scanning the pixels line by line;
(b) assigning a first instruction to a plurality of successive pixels depicting the image background, wherein the first instruction indicates the number of successive background pixels; and
(c) assigning a second instruction to a plurality of successive data pixels, wherein the second instruction indicates the number of successive data pixels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for forming a bit stream representing a compressed graphical weather image representing precipitation intensity over a geographical area, wherein the graphical weather image comprises a plurality of pixels for display, and wherein the plurality of pixels comprise background pixels all of a background color for depicting the image background and data pixels each having one of a plurality different colors, and wherein the data pixel color represents the precipitation intensity, said method comprising:
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(a) deleting background and data pixels from predetermined areas of the image;
(b) scanning the pixels line by line;
(c) identifying data pixel segments within a line of pixels, wherein a data pixel segment comprises a plurality of successive data pixels, and wherein if there are less than a predetermined number of data pixels within the data pixel segment, changing the color of each data pixel within the data pixel segment to the background color;
(d) assigning a first instruction representing the number of successive lines composed entirely of background pixels;
(e) determining the number of successive background pixels in a line;
(f) assigning a second instruction representing the number of successive background pixels in a line;
(g) assigning a third instruction representing the number of successive data pixels in a line, wherein the third instruction comprises a first field representing the number successive data pixels and a second field representing the color of each successive data pixel; and
(h) concatenating the first, second and third instructions to form the bit stream. - View Dependent Claims (14, 15, 16)
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17. A method of reconstructing a graphical weather image from a bit stream, wherein display parameters for a plurality of pixels are derived from the bit stream and drive a visual display, wherein the graphical weather image represents precipitation intensity over a geographical area, and wherein the graphical weather image comprises a plurality of pixels comprising background pixels of a background color for depicting the image background and data pixels each having one of a plurality different colors, and wherein the data pixel color represents the precipitation intensity, and wherein the said method comprises:
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(a) identifying within the bit stream a first instruction representing the number of successive lines composed entirely of background pixels;
(b) producing a first number of pixels with a background display parameter, wherein the first number of pixels equals the number of pixels in the number of successive lines determined at the step (a);
(c) identifying within the bit stream a second instruction representing the number of successive background pixels in a display line;
(d) producing a second number of pixels with a background display parameter, wherein the second number of pixels equals the number of successive background pixels determined at the step (c);
(e) identifying a third instruction in the bit stream representing the number of successive data pixels in a line, wherein the third instruction comprises a first field representing the number of successive data pixels and a second field representing the color of each successive data pixel;
(f) producing a third number of pixels with a color display parameter, wherein the third number of pixels equals the value in the first field, and wherein the color display parameter for each one of the third number of pixels includes the color as set forth in the second field; and
(g) inputting the display parameters for the first, the second and the third number of pixels to the display for forming the visual image thereon.
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18. A system for providing a graphical weather image to an aircraft, wherein the graphical weather image comprises a plurality of pixels, and wherein each one of the plurality of pixels further comprises a plurality of bits for controlling a display to display the graphical weather image, and wherein the graphical weather image comprises a background color and a plurality of information colors, wherein each one of the plurality of information colors denotes a precipitation intensity, said system comprising:
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a data compressor for receiving data bits representing the pixels comprising the graphical weather image and for producing a compressed data bit stream by compressing the data bits according to the number of successive pixels of the background color and the number of successive pixels of the information color;
a carrier signal;
a modulator for modulating the carrier signal with the compressed bit stream;
a transmitter for transmitting the modulated carrier signal;
a receiver in the aircraft for receiving the modulated carrier signal;
a demodulator responsive to the received modulated carrier signal for recovering the compressed bit stream;
a data decompressor for decompressing the recovered compressed bit stream for producing the recovered data bits representing the pixels comprising the graphical weather image, by determining the number of successive pixels of the background color and the number of successive pixels of the information color; and
a display responsive to the recovered data bits for displaying the pixels comprising the graphical weather image. - View Dependent Claims (19, 20)
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Specification