Abstract: A picture processing apparatus in which the color appearance of a soft copy image and that of a hard copy picture coincide with each other with high precision despite difference in the optical environment. A first conversion unit 12 is responsive to the optical environmental parameters specifying a picture handled by an input device 3 to convert picture data from the input device 3 corresponding to a picture handled by the input device 3 into index data for color appearance associated with the appearance under the ambient light. A second conversion unit 14 is responsive to the optical environmental parameters specifying the luminance of the ambient light in which to observe the picture handled by the output device 4 to convert the color appearance index data obtained by the first conversion unit 12 so that the color appearance under the ambient light will be coincident with the color appearance under the ambient light under which to view the picture handled by the input device 3.

Abstract: A system and method for determining a black threshold grey value for an image. A histogram is generated corresponding to possible grey values of the image and a first grey value having a peak frequency associated with a black distribution is determined from the histogram. A second grey value having a peak frequency equal to one quarter of the peak frequency associated with the first grey value, a third grey value having a peak frequency equal to 5/8 of the peak frequency associated with the first grey value, a fourth grey value located on a negative slope-side of the first grey value having a peak frequency equal to one quarter of the peak frequency associated with the first grey value, and a fifth grey value having a minimum peak frequency associated with the histogram are also determined. A black threshold grey value for the image is calculated from the first, second, third, fourth, and fifth grey values.

Abstract: An apparatus for deciding DCT block classes in a DVCR includes a scanning section for scanning AC coefficients among coefficients of respective DCT blocks, an absolute-value getting section for taking absolute values of the AC coefficients, a maximum value detecting section for obtaining the maximum values of respective DCT blocks from outputs of the absolute-value getting section, a minimum value detecting section for obtaining the minimum values from the maximum values of the DCT blocks obtained by the maximum value detecting section, and a deciding section for comparing outputs of the minimum value detecting section as threshold values with outputs of maximum value detecting section to decide the classes with respect to the DCT blocks.