ENCODER, DECODER, RECORDING MEDIUM, ENCODING METHOD, AND DECODING METHOD

摘要

To compress images using transition information of adjacent pixels, index transition patterns of two adjacent pixels in the horizontal scanning direction of an image are computed and arranged in order of appearance frequency, then patterns within the upper four appearance frequencies are selected to create a reference table. Then, with reference to the created reference table, image data are encoded. When decoding the encoded data, at first data from both the reference table and the color look-up table is inputted and stored in the table 50 and the color look-up table 53. After this, the first data of the subsequent input data is supplied to both the color look-up table 53 and the delay circuit 51 by changing over the connection of the switch 52. Subsequent data is supplied to the table 50. The table 50 decodes the data to original image data with reference to the data and the output from the delay circuit 51. The color look-up table 53 then converts the decoded data to R, G, and B signals and output the signals.