| 摘要 |
<p>PURPOSE:To realize high compression efficiency and high S/N even for images photographed with low illuminance. CONSTITUTION:An orthogonal transformation circuit 20 executes orthogonal transformation such as DCT, for example, to photographed images to be stored in a memory 18. A system control circuit 40 investigates the state of the photographed images and controls the characteristic of a quantizer circuit 22 according to the coefficients of a DC component and a high frequency component outputted from the orthogonal transformation circuit 20. Concretely, when the DC component is small and the high frequency component is large, the characteristic of the quantizer circuit 22 is changed so that the coefficient of the high frequency component higher than a certain level can be reduced or turned to zero.</p> |
