BS ISO IEC 18477-6 pdf download

BS ISO IEC 18477-6 pdf download.Information technology — Scalable compression and coding of continuous-tone still images
3 Terms and definitions, abbreviated terms, and symbols
3.1 Terms and definitions For the purposes of this document, the following definitions apply. 3.1.1 AC coefficient any DCT coefficient for which the frequency is not zero in at least one dimension 3.1.2 ASCII encoding encoding of text characters and text strings according to ISO/IEC 10646-1 3.1.3 base decoding path process of decoding legacy codestream and refinement data to the base image, jointly with all further steps until residual data is added to the values obtained from the residual codestream 3.1.4 base image collection of sample values obtained by entropy decoding the DCT coefficients of the legacy codestream and the refinement codestream, and inversely DCT transforming them jointly 3.1.5 binary decision choice between two alternatives 3.1.6 bitstream partially encoded or decoded sequence of bits comprising an entropy-coded segment 3.1.7 block 8 × 8 array of samples or an 8 × 8 array of DCT coefficient values of one component 3.1.8 box structured collection of data describing the image or the image decoding process embedded into one or multiple APP 11 marker segments Note 1 to entry: See ISO/IEC 18477-3:2015, Annex B for the definition of boxes. 3.1.9 byte group of 8 bits 3.1.10 coder embodiment of a coding process 3.1.11 coding encoding or decoding 3.1.12 coding model procedure used to convert input data into symbols to be coded 3.1.13 (coding) process general term for referring to an encoding process, a decoding process, or both 3.1.14 compression reduction in the number of bits used to represent source image data 3.1.15 component two-dimensional array of samples having the same designation in the output or display device Note 1 to entry: An image typically consists of several components, e.g. red, green, and blue. 3.1.16 continuous-tone image image whose components have more than one bit per sample 3.1.17 DC coefficient DCT coefficient for which the frequency is zero in both dimensions 3.1.18 decoder embodiment of a decoding process 3.1.19 decoding process process which takes as its input compressed image data and outputs a continuous-tone image 3.1.20 dequantization inverse procedure to quantization by which the decoder recovers a representation of the DCT coefficients 3.1.21 discrete cosine transform DCT either the forward discrete cosine transform or the inverse discrete cosine transform 3.1.22 downsampling procedure by which the spatial resolution of a component is reduced 3.1.23 encoder embodiment of an encoding process 3.1.24 encoding process process which takes as its input a continuous-tone image and outputs compressed image data 3.1.25 entropy-coded (data) segment independently decodable sequence of entropy encoded bytes of compressed image data 3.1.26 entropy decoder embodiment of an entropy decoding procedure 3.1.27 entropy decoding lossless procedure which recovers the sequence of symbols from the sequence of bits produced by the entropy encoder 3.1.28 entropy encoder embodiment of an entropy encoding procedure 3.1.29 entropy encoding lossless procedure which converts a sequence of input symbols into a sequence of bits such that the average number of bits per symbol approaches the entropy of the input symbols 3.1.30 grayscale image continuous-tone image that has only one component 3.1.31 high dynamic range image or image data comprised of more than eight bits per sample 3.1.32 Huffman decoder embodiment of a Huffman decoding procedure 3.1.33 Huffman decoding entropy decoding procedure which recovers the symbol from each variable length code produced by the Huffman encoder 3.1.34 Huffman encoder embodiment of a Huffman encoding procedure 3.1.35 Huffman encoding entropy encoding procedure which assigns a variable length code to each input symbol 3.1.36 intermediate dynamic range image or image data comprised of more than eight bits per sample 3.1.37 joint photographic experts group JPEG informal name of the committee which created this part of ISO/IEC 18477 Note 1 to entry: The “joint” comes from the ITU-T and ISO/IEC collaboration.