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EP0774855A2
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A method and system for performing perspective projection conversion
Assignee: Xerox Corp
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Filing: 1996-11-14
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Granted: —
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Expires: 2016-11-14
Abstract
Abstract A system and process prints a high resolution image on a high addressable image output terminal by converting an image at one resolution to an image having a lower resolution in a fast-scan direction and a higher resolution in a pixel depth direction. The converted image is then processed and binarized prior to being printed on a high addressable printer. The system or process utilizes a conversion circuit which includes a two-bit per pixel packing circuit, a scanline buffer circuit, a logic circuit, and a look-up table. The conversion circuit initially converts the image into an image having a lower resolution in the fast-scan direction and a higher pixel depth resolution. Thereafter, the image is further converted to an image having a lower resolution in the slow-scan direction and a higher pixel depth resolution. This conversion of a high resolution image to a lower resolution is carried without any substantial lost to the image content data.
Inventors
- 👤 Thomas I. Yeh
- 👤 Francis K. Tse
- 👤 George W. Lahue
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 15:36
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40075
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
76 words
A method for converting a high resolution binary image to a gray scale low resolution image, comprising the step of: (a) converting a first image having a first fast-scan resolution and a first pixel depth resolution to a second image having a second fast-scan resolution and a second pixel depth resolution, the second fast-scan resolution being lower than the first fast-scan resolution and the first pixel depth resolution being lower than the second pixel depth resolution.
Claim 2
Independent Claim
61 words
A method for converting a high resolution image having information content to a low resolution image having information content, comprising the steps of: (a) converting a first image having high fast-scan and slow-scan resolutions to a second image having lower fast and slow-scan resolutions; and (b) preserving substantially all of the information content of the first image in the second image.
Claim 3
Dependent Claim
102 words
The method as claimed in claim 1 or 2, wherein said step (a) comprises converting (A) a three pixel by three pixel area of the first image having a resolution of 1800x1800x1 to the second image having a resolution of 600x600x8, (B) a two pixel by two pixel area of the first image having a resolution of 1200x1200x1 to the second image having a resolution of 600x600x8, or (C) a three pixel by three pixel area of the first image having a resolution of 900x900x1 to a two pixel by two pixel area of the second image having a resolution of 600x600x8.
Claim 4
Dependent Claim
249 words
The method as claimed in claim 1, 2 or 3, wherein said step (a) comprises (A) the substeps of: (a1) counting a number of ON pixels in a predetermined number of adjacent fast-scan pixels of the first image; (a2) generating a pixel having a pixel depth resolution of two and a value corresponding to the number of ON pixels counted in said substep (a1); (a3) summing a predetermined number of pixels generated in said substep (a2) which are adjacent in a slow-scan direction; and (a4) using the sum to index a look-up table which contains grayscale pixel values, or (B) the substeps of: (a1) generating a pixel having a pixel depth resolution of two from a predetermined number of fast-scan pixels of the first image; (a2) summing a predetermined number of pixels generated in said substep (a1) which are adjacent in a slow-scan direction; and (a3) using the sum to index a look-up table which contains grayscale pixel values, or (C) substeps of: (a1) generating a pixel having a pixel depth resolution of two from a predetermined number of fast-scan pixels of the first image; and (a2) using values of a predetermined number of the generated pixels adjacent in both a fast-scan and slow-scan direction to index a look-up table which contains grayscale pixel values or pixel values corresponding to a fast-scan resolution being lower than the fast-scan resolution of the first image and a pixel depth resolution being higher than the pixel depth resolution of the first image.
Claim 5
Dependent Claim
53 words
The method as claimed in claim 4(B), wherein the predetermined number of adjacent fast-scan pixels is three and the predetermined number of generated pixels in three, or as claimed in claim 4(B) or 4(C) wherein the predetermined number of adjacent fast-scan pixels is two and the predetermined number of generated pixels is two.
Claim 6
Dependent Claim
51 words
The method as claimed in claim 4(B), wherein said substep (a1) generates two pixels having a pixel depth resolution of two from three fast-scan pixels of the first image and said substep (a2) produces two sums by summing two out of three generated pixels which are adjacent in a slow-scan direction.
Claim 7
Dependent Claim
54 words
The method as claimed in claim 4(C), wherein said substep (a1) generates two pixels having a pixel depth resolution of two from three fast-scan pixels of the first image and said substep (a2) uses values of two out of three generated pixels which are adjacent in a slow-scan direction to index the look-up table.
Claim 8
Dependent Claim
24 words
A perspective projection resolution conversion circuit, comprising: a two-bit per pixel packing circuit; a scanline buffer circuit; a logic circuit; and a memory device.
Claim 9
Dependent Claim
68 words
The circuit of claim 8, wherein: the packing circuit is adapted for packing a predetermined of pixels of an original image into a two-bit per pixel; the scanline buffer circuit is adapted for buffering said two-bit per pixels; the logic circuit is adapted for generating an address from the buffered pixels; and the memory device is adapted for storing grayscale pixel values, and preferably includes a look-up table.
Claim 10
Dependent Claim
211 words
The circuit as claimed in claim 8 or 9, wherein said two-bit per pixel packing circuit includes (A) means for converting three pixels of the image having the resolution of 1800x1800x1 to a pixel of an image having a resolution of 600x1800x2; said logic circuit including means for summing three pixels of the image having a resolution of 600x1800x2 to generate an address; said memory device providing a pixel of the image having the resolution of 600x600x8 from the generated address, (B) means for converting two pixels of the image having the resolution of 1200x1200x1 to a pixel of an image having a resolution of 600x1200x2; said logic circuit including means for generating an address from two pixels of the image having the resolution of 600x1200x1; said memory device providing a pixel of the image having the resolution of 600x600x8 from the generated address, or (C) means for converting nine pixels of the image having the resolution of 900x900x1 to four pixels of an image having a resolution of 600x600x4; said logic circuit including means for generating an address from one of the pixels of the image having a resolution of 600x600x4; and said memory device providing a pixel of the image having the resolution of 600x600x8 from the generated address.
References Cited (Backward Citations)
EP0696132A2
Cited
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