| 摘要 |
PURPOSE:To optimize a data quantity obtained by compressing/encoding image data and to optimally decode encoded data by selectively switching plural kinds of variable length encoding tables obtained statistically in advance in accordance with the data quantity. CONSTITUTION:Three kind of variable length encoding tables (40b, 41b and 42b for brightness and 40c, 41c and 42c for color difference) are in a control part 4 and connected in parallel. The both data of brightness and color difference are sumed by data number counting part 40d, 41d and 42d and inputted to a selection part 45. The number of a variable length encoding part being the smallest value among the three kinds thereof, is sent to a switching control part 44. At the time of sending a next image, the control part 44 switches the variable length encoding part by using this number. This operation is executed for each time of sending one image to optimally control the data quantity to be transmitted by using the data quantity of the picture sent just before. A table selecting number is incorporated in a data frame by a frame forming part 46 and outputted as encoded data. At the time of decoding, the incorporated number is deciphered and decoded by using 1 the selected variable length encoding table. |
