Patent TW-347634-B (TW)
Title: Apparatus and method for uniformly two-dimensional scaling of a digital image (addition one)
Inventor: SHYU RONG-FUH
IPC: H04N1/41
Filed: 1996-10-17
Granted: 1998-12-11
Abstract: An apparatus for processing an original digital image to obtain a uniformly scaled desired digital image, the apparatus including a frame memory for storing the original digital image therein, the original digital image having a number (N) of successive original scan lines and a number (N^) of successive original pixel data per original scan line, the apparatus further including a vertical scaling unit for scaling the original digital image in a vertical direction to obtain a number (M) of successive desired scan lines, and a horizontal scaling unit for scaling the desired scan lines from the vertical scaling unit in a horizontal direction to obtain a number (M^) of successive desired pixel data per scan line, the number (M) being greater than the number (N), the number (M^) being greater than the number (N^), the apparatus being characterized in that: the vertical scaling unit includes: a line memory connected to the frame memory for storing an (n+1)th one of the original scan lines from the frame memory therein; a line buffer connected to the line memory for storing an (n)th one of the original scan lines therein; a first linear interpolator connected to the line memory and the line buffer; and a vertical scaling controller connected to the frame memory, the line buffer and the first linear interpolator, the vertical scaling controller controlling the storage of the original scan lines in the line memory and the line buffer, the vertical scaling controller further controlling the first linear interpolator to perform a linear interpolation of the (n)th and (n+1)th ones of the original scan lines from the line memory and the line buffer to produce a residual interpolated scan line inserted therebetween when division of (M-N) by (N-1) results in a remainder (S) and when (n) is a minimum number which meets a condition (n+1)*(S)≧(N), in which (s) ranges from 1 to (S); and the horizontal scaling unit includes: a dot register connected to the first linear interpolator for storing an (n^+1)th one of the pixel data of one of the scan lines from the first linear interpolator therein; a dot buffer connected to the dot register for storing an (n^)th one of the pixel data of said one of the scan lines therein; a second linear interpolator connected to the dot register and the dot buffer; and a horizontal scaling controller connected to the line memory, the line buffer, the dot buffer and the second linear interpolator, the horizontal scaling controller controlling the storage of the pixel data in the dot register and the dot buffer, the horizontal scaling controller further controlling the second linear interpolator to perform a linear interpolation of the (n^)th and (n^+1)th ones of the pixel data from the dot register and the dot buffer to produce a residual interpolated pixel data inserted therebetween when division of (M^-N^) by (N^-1) results in a remainder (S^) and when (n^) is a minimum number which meets a condition (n^+1)*(S^)≧(s^)*(N^), in which (s^) ranges from 1 to (S^); whereby the output of the second linear interpolator can be provided directly to an output device.