In an apparatus for coding digital video data in the form of blocks thereof dynamic range information is generated from maximum and minimum values of the digital video data representing plural picture elements in each block, the minimum value is substracted from each of the digital data to generate modified digital video data, the modified digital video data is encoded with a fixed digitized bit number less than that of the original digital video data, and the encoded data and an additional code for each block are transmitted, with such additional code being formed of at least two of the maximum and minimum values for the respective block and a signal corresponding to the dynamic range information for each block.
A method of coding a digital video signal is characterized by forming a block by grouping together a specific number of pixels from an input digital video signal, setting a quantizing level consisting of a number of levels less than a number of levels determined by a data word length of pixel in every block, quantizing, coding and transmitting the plural pieces of pixel data in each block, and transmitting by coding by combining together at least two pieces of side information necessary for determining the quantizing level in each block.
An apparatus for concealing error data of pixel data in a digital image signal. The apparatus includes a deframing circuit for detecting errors every predetermined unit to generate a first error flag in high order bit planes including at least the most significant bit plane of bit planes of pixel data in a received digital image signal and for forming a second error flag representing the presence or absence of an error in each of the bits forming the pixel data every pixel data in the high order bit planes on the basis of the first error flag. The apparatus further includes an error correcting device for calculating a plurality of possible data values of the pixel data and for selecting one data value from among the plurality of possible data values, taking the correlation between the pixel data and surrounding pixel data into consideration, on the basis of the second error flag representing the presence or absence of an error in each of the bits forming the pixel data when the pixel data has an error.
An image signal encoding apparatus for encoding an image signal in which image of one picture plane consisting of a plurality of pixel data are divided into a plurality of blocks each consisting of a predetermined number of pixel data. For each of the blocks, a pair of reference value data regarding the maximum and minimum values of the levels of the pixel data constructing the block are formed. On the basis of the formed reference value data, encoded date is formed by encoding each of the pixel data of the block. Decoded data is formed by decoding the encoded data formed on the basis of the reference value data. By comparing each of the pixel data of the block with the decoded data, errors are detected. The reference value data are corrected in accordance with the result of the detection. Thus, the encoding errors are reduced and it is possible to perform the encoding with less deterioration in picture quality of the image signal.
Digital video signals are divided in blocks, maximum and minimum values of each block are extracted, and a frequency distribution of one frame period of a dynamic range in each block is detected. The coding condition is determined by the frequency distribution and a predetermined N kinds of characteristic tables, and by determining only one characteristic table, the signal obtained by subtracting the minimum value of each block from the digital video signals of each block is coded in variable length according to the dynamic range of each block. The characteristic table shows the relationship of the distortion or the number of quantization bits between the original signal and decoded signal after coding and decoding with respect to the dynamic range of digital video signal in each block, and the picture quality of decoded image is set as a parameter.
An image information transmission apparatus of this invention encodes and transmits image information. An image information signal of one frame consisting of a plurality of pixel data is divided into a plurality of blocks each consisting of a predetermined number of pixel data. At least two reference value data associated with a dynamic range of levels of the pixel data constituting each of the divided blocks, and distribution state data associated with a distribution state thereof are formed. Each pixel data constituting the block is encoded on the basis of the formed reference value data and the formed distribution state data to obtain encoded data. A transmission data series is formed and transmitted using the formed reference value data, the formed distribution state data, and the encoded data as transmission units. Therefore, the image information signal can be highly effectively transmitted with minimum image quality degradation caused by encoding.
