| 摘要 |
The types of pixels of an image made up of a plurality of pixels arranged in a main scanning direction and a sub-scanning direction are distinguished. The image is divided into a plurality of blocks each substantially larger than a visually distinguishable size, properties of the images in the blocks representing the probability that the image is a binary image are detected, probability that the image in each block is a binary image is determined on the basis of the detected properties of the image in the block, and the blocks are divided into a binary image block, a tone image block, and an indeterminate image block according to the probability that the image is a binary image. The pixels in the blocks which are determined to be a binary image block are all determined to be pixels of a binary image while the pixels in the blocks which are determined to be a tone image block are all determined to be pixels of a tone image. Then a pixel-by-pixel determination is carried out on the blocks, which are determined to be an indeterminate image block by the block-by-block determination, in which properties of each of the pixels in each of the indeterminate blocks representing the probability that the pixel is of a binary image are detected, and whether the pixel is a pixel of a binary image is determined on the basis of the detected properties.
|
