An image data processing apparatus

Claim 2

An image data compressing apparatus comprising: an orthogonally transforming means [111] for obtaining a coefficient matrix comprising N rows and N columns of transform coefficients by two-dimensionally orthogonally transforming continuous-tone image data in block units each having NXN picture elements; a quantizing means [121] for quantizing respective elements of a coefficient matrix obtained by said orthogonally transforming means [111] by corresponding quantization thresholds and for outputting quantized coefficients, being the results of quantizing respective elements of said coefficient matrix, in a predetermined sequence; a selecting means [131] for sequentially receiving quantized coefficients obtained by said quantizing means [121] for selecting significant coefficients having non-zero values from among said quantized coefficients, and for sequentially outputting said significant coefficients; a counting means [132] for sequentially receiving said quantized coefficients, and for counting the number of successive inputs of insignificant coefficients having the zero value, and for outputting counting results as insignificant coefficient succession lengths upon each receipt of the corresponding one of said significant coefficients; a first storing means [141] for sequentially storing data pairs, each of said data pairs comprising one of said significant coefficients obtained by said selecting means [131] and the corresponding one of said insignificant coefficient succession lengths obtained by said counting means [132]; and a coding means [150] for outputting codes respectively corresponding to said data pairs read out from said first storing means, each of said data pairs each comprising one of said significant coefficients and said corresponding one of said insignificant coefficient succession lengths.

Claim 3

The image data compressing apparatus according to claim 2, wherein: said selecting means [131] operates in parallel with said counting means [132].

Claim 4

The image data compressing apparatus according to claim 2, wherein said coding means [150] comprises: a coefficient converting means [151] for converting parts corresponding to significant coefficients of data pairs stored in said first storing means [141] into appropriate coefficient codes; a succession length converting means [152] for converting parts corresponding to insignificant coefficient succession lengths of said data pairs into appropriate succession length codes; and a code generating means [153] for generating a code corresponding to a pair comprising a coefficient code obtained by said coefficient converting means [151] and a succession length code obtained by said succession length converting means [152].

Claim 5

The image data compressing apparatus according to claim 2, wherein: said first storing means [141] has a memory capacity for storing data pairs corresponding to two (2) blocks of said image data; and said coding means [151] codes the already stored data pairs in parallel with operations for generating and storing data pairs by said quantizing means [121], said selecting means [131] and said counting means [132].

Claim 6

An image data compressing apparatus comprising: an orthogonally transforming means [211] for obtaining a coefficient matrix comprising N rows and N columns of transform coefficients by two-dimensionally orthogonally transforming continuous-tone image data in block units each having NXN picture elements; a quantizing means [221] for quantizing respective elements of a coefficient matrix obtained by said orthogonally transforming means [211] by corresponding quantization thresholds and for outputting quantized coefficients, being the results of quantizing respective elements of said coefficient matrix, in a predetermined sequence; a converting means [231] for converting a series of quantized coefficients outputted from said quantizing means [221] into serial quantized coefficients comprising significant coefficients having non-zero values each paired with the corresponding one of insignificant coefficient succession lengths indicating the numbers of successive insignificant coefficients having the zero value; a generating means [241] for generating a predetermined termination signal; an attaching means [251] for outputting serial quantized coefficients obtained by said converting means [231] by attaching a termination signal generated by said generating means [241] to the tail end of said serial quantized coefficients; a coding means [261] for outputting codes respectively corresponding to significant coefficients each paired with said corresponding one of insignificant coefficient succession lengths included in serial quantized coefficients outputted from said attaching means [251]; and an instructing means [271] for instructing said coding means [261] of a termination of a process for coding a block upon detecting said termination signal during a receipt of said serial quantized coefficients.

Claim 7

The image data compressing apparatus according to claim 6, wherein: said generating means [241] comprises a first generating means [242] for generating a predetermined first termination signal, a second generating means [243] for generating a different second termination signal, and a selecting means [244] for selectively outputting, as a termination signal, either said first termination signal or said second termination signal, depending on whether or not a quantized coefficient outputted last from said quantizing means [221] is an insignificant coefficient; and said instructing means [271] comprises a judging means [272] for judging whether said termination signal is a first termination signal or a second termination signal, and instructs said coding means [261] of a termination of coding for a block according to the judging result of said judging means [272].

Claim 8

An image data reconstructing apparatus for reconstructing image data based on input codes created by coding coefficient codes and succession length codes converted from significant coefficients and insignificant coefficient succession lengths produced from among quantized coefficients obtained by quantizing the result of two-dimensionally orthogonally transforming image data in block units each comprising NXN picture elements, said image data reconstructing apparatus comprising: a decoding means [161] for decoding said input codes to said coefficient codes and succession length codes; a coefficient code reverting means [162] for reverting coefficient codes obtained by said decoding means [161] into corresponding significant coefficients; a succession length code reverting means [163] for reverting succession length codes obtained by said decoding means [161] into corresponding insignificant coefficient succession length; a second storing means [142] for storing, as a data pair, a pair composed of a significant coefficient obtained by said coefficient code reverting means [162] and an insignificant coefficient succession length obtained by said succession length code reverting means [163]; a dequantizing means [171] for obtaining appropriate transform coefficients by dequantizing significant coefficients based on significant coefficients and insignificant coefficient succession lengths expressed as data pairs read out from said second storing means [142] and for outputting said transform coefficients as corresponding elements of a coefficient matrix having N rows and N columns; and an inverse orthogonally transforming means [181] for two-dimensionally inverse-orthogonally transforming a coefficient matrix obtained by said dequantizing means [171] and for outputting the transforming result as image data.

Claim 9

The image data reconstructing apparatus according to claim 8, wherein: said coefficient code reverting means [162] operates in parallel with said succession length code reverting means [163].

Claim 10

The image data reconstructing apparatus according to claim 8, wherein: said second storing means [142] has a memory capacity for storing data pairs for two (2) blocks of said image data; and said dequantizing means [171] dequantizes the already stored data pair in parallel with operations for generating and storing data pairs by said decoding means [161], said coefficient code reverting means [162] and said succession length code reverting means [163].