1. An image coding apparatus, comprising: a plurality of pixel value predicting means for sequentially selecting pixels in image data to be processed as pixels of interest in a predetermined scanning order and generating predicted pixel values of the pixels of interest, each pixel value predicting means generating a predicted pixel value based on a pixel value of a predicting pixel located at a distance from the pixel of interest predetermined for each pixel value predicting means; run-length count means for counting, as a run-length for each pixel value predicting means, the number of times that the pixel values of the sequentially selected pixels of interest successively correspond with the predicted pixel values generated by each pixel value predicting means based on a relationship between the pixels of interest and the predicting pixels; selecting means for selecting any of pixel value predicting means related to a run-length of one pixel or more; and coding means for referring to a predetermined code table with respect to a distance between the pixel of interest and the predicting pixel determined for the selected pixel value predicting means and the run-length related to said selected pixel value predicting means and outputting a resulting code, wherein said code table is defined to include, as a redundant code, a code related to a distance other than the distances between the pixel of interest and the predicting pixels.