Restoration of Color Halftone Image by Using Fast Inverse Half Toning Algorithm

A fast inverse half toning algorithm is used for error diffused halftones. Halftones and other binary images are difficult to process cause several degradations. Jarvis´s halftoning operator is used to obtain sharper halftone image. Color image of 24-bit BMP formats splits image into 8- bit R-G-B planes. Degradation is greatly reduced if the halftone is inverse halftone (converted to gray scale) before scaling, or other processing. At each pixel, the proposed algorithm applies a separable 7 times 7 FIR filter. The filter passes in vertical and horizontal direction separately and computes vertical and horizontal edge strengths from local gradients. It requires entirely local operations and storage of 7 rows. We compare our algorithm with previously reported approaches to show that it delivers comparable subjective quality at a fraction of the computation and memory usage.