| 摘要 |
<p>PURPOSE:To provide for high quality picture data compression by simple construction by dividing the signal output of the photodetector into plural level ranges and counting the frequency of occurrence of output signals in the domains for predetermined time to find the level that will give the smallest of the number of times the occurrence. CONSTITUTION:The picture data from the photodetector 6 is inputted to a level division circuit 12 after primary processing. The circuit 12 divides the input signals into plural level domains and the counting circuit 14 counts the number of times of occurrence of the signals in the respective domains for a predetermined time duration. A discrimination level setting circuit 15 divides the signal output of the element 6 into plural level groups by comparing the magnitude of the results of counting of the circuit 14 and finding the level that gives the smallest frequency value. The maximum value of the difference of signal outputs within the level groups is detected in a level setting circuit 52 for setting the quantization range for each level group. Sample hold circuits 17, 18 are in operation only for input signals corresponding to the respective level groups. An encoding circuit 25 sets the quantization level range for the output while a multiplexing circuit 27 inserts an identification code to the encoder output to output the resulting signal.</p> |
