| 摘要 |
PURPOSE:To execute AE inexpensively by executing the AE by utilizing the DC component of a picture obtained in the course of picture compression processing. CONSTITUTION:After passing through a lens 1, a CCD 2, and an image pickup processing part 3, the output of an A/D converter 4 is stored in a frame memory 17 by one picture portion. The two-dimensional discrete cosine transformation of 8X8 picture element information is executed from the memory 17 by a DCT part 18. A 8X8 matrix F(U, V) corresponds to the transformation coefficients of the U/2N- times lower frequency and the V/2N-times lower frequency of the highest frequency included in the picture, and Y00 corresponds to the coefficient of the DC component, and it is the mean value of 8X8 picture elements. A microcomputer 9 integrates the coefficient Y00, and if a result is within the range of a prescribed level, it decides the AE to be completed, and displays it on a display part 11. If the result is out of the range, it controls an iris or shutter opening time, and optimizes the input quantity of light of the CCD 2. The output of the DCT is inputted to an SQ linear encoder 19, and is converted into a one-dimensional predictive code, and the coefficients other than Y00 are zigzag-scanned, and after being variable-length-encoded, an encoded output 6 is obtained through a VLC fixed Hoffman encoder 20. |
