Image transformation method and device
First Claim
1. An image transformation method for transforming a rectangular source image formed by pixels in a two-axis coordinate system to a destination image formed by pixels disposed on scan lines, comprising the steps of:
- (a) mapping vertices of said source image onto vertices of said destination image by a coordinate transformation;
(b) finding intersections of scan lines with edges of said destination image and mapping these intersections onto edges of said source image;
(c) mapping scan lines in said destination image onto said source image, and assigning to pixels on said scan lines the values of corresponding pixels in said source image; and
(d) displaying said destination image by scanning according to said scan lines.
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Abstract
A rectangular source image formed by pixels in a two-axis coordinate system is transformed to a destination image by mapping vertices of the source image onto vertices of the destination image, then mapping edges of the destination image onto edges of the source image, mapping scan lines in the destination image onto the source image, and assigning to pixels on these scan lines the values of corresponding pixels in the source image. DDA algorithms are employed for the edge mapping and scan line mapping steps. This method enables arbitrary affine transformations, including combinations of a rotation with an enlargement or reduction, to be executed without introducing image defects.
54 Citations
19 Claims
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1. An image transformation method for transforming a rectangular source image formed by pixels in a two-axis coordinate system to a destination image formed by pixels disposed on scan lines, comprising the steps of:
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(a) mapping vertices of said source image onto vertices of said destination image by a coordinate transformation; (b) finding intersections of scan lines with edges of said destination image and mapping these intersections onto edges of said source image; (c) mapping scan lines in said destination image onto said source image, and assigning to pixels on said scan lines the values of corresponding pixels in said source image; and (d) displaying said destination image by scanning according to said scan lines. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An image transformation method for transforming a rectangular source image formed by pixels in a two-axis coordinate system to a destination image formed by pixels disposed on scan lines, comprising the steps of:
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(a) mapping vertices of said source image onto vertices of said destination image, said mapping vertices of said source image step including the substeps of; (a1) receiving parameters describing one or more affine transformations; (a2) combining said parameters to generate a product transformation; and (a3) applying said product transformation to said vertices of said source image; (b) finding intersections of scan lines with edges of said destination image and mapping these intersections onto edges of said source image; (c) mapping scan lines in said destination image onto said source image, and assigning to pixels on said scan lines the values of corresponding pixels in said source image; and (d) displaying said destination image by scanning according to said scan lines. - View Dependent Claims (11, 12, 13, 14)
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10. An image transformation device for transforming a rectangular source image formed by pixels in a two-axis coordinate system to a destination image formed by pixels disposed on scan lines, comprising:
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a source image memory for storing said source image; a destination image memory for storing said destination image; affine transformation means for performing an affine transformation on vertices of said source image to generate vertices of said destination image; edge mapping means for mapping pixels on edges of said destination image to pixels on edges of said source image; scan line mapping means for mapping pixels on scan lines in said destination image to pixels in said source image; controller means for controlling said affine transformation means, said edge mapping means, and said scan line mapping means, and for transferring values of pixels from said source image memory to said destination image memory as indicated by said scan line mapping means; a data bus for interconnecting said source image memory, said destination image memory, and said controller means; and display means for displaying images stored in said destination image memory. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification