Patent ID: 7293180

Claim:
An apparatus for encryptically processing digital video data, followed by an encoding procedure to the processed digital video data with orthogonal transform to produce a coded video signal, the apparatus comprising: a representative-value calculator to obtain a representative value of luminance data of a plurality of pixels of the digital video data for each of pixel blocks having a predetermined number of pixels, each pixel block corresponding to a unit of data subjected to the encoding procedure, as a quantized integer for each pixel block by using a specific function with the stored luminance data as a parameter; a data rewriter to determine whether the quantized integer of the representative value for each pixel block is a multiple of a preset integer N of two or larger, and, if not, rewrite the stored luminance data with a specific requirement giving the least range of change in gradation so that the quantized integer becomes a multiple of the integer N, whereas the stored luminance data remain unchanged if the quantized integer is a multiple of the integer N, thus encryptically processing the digital video data; and an encoder to encode the encryptically processed digital video data with orthogonal transform to produce a coded video signal.