Lines Matching refs:JPEG
1 IJG JPEG LIBRARY: SYSTEM ARCHITECTURE
3 This file was part of the Independent JPEG Group's software:
10 This file provides an overview of the architecture of the IJG JPEG software;
15 We assume that the reader is already somewhat familiar with the JPEG standard.
16 The README.ijg file includes references for learning about JPEG. The file
21 In this document, JPEG-specific terminology follows the JPEG standard:
40 * A subroutine library for JPEG compression and decompression.
42 JFIF JPEG files to and from several other image formats.
47 We desire the library to be capable of supporting all JPEG baseline, extended
51 The library does not support the lossless (spatial) JPEG process. Lossless
52 JPEG shares little or no code with lossy JPEG, and would normally be used
54 We feel that lossless JPEG is better handled by a separate library.
56 Within these limits, any set of compression parameters allowed by the JPEG
65 By itself, the library handles only interchange JPEG datastreams --- in
67 surrounding code to process interchange or abbreviated JPEG datastreams that
69 library to implement JPEG compression within the TIFF file format.)
72 JPEG standard but is necessary for typical applications of JPEG. These
73 functions preprocess the image before JPEG compression or postprocess it after
77 A wide range of quality vs. speed tradeoffs are possible in JPEG processing,
83 low-quality modes may not meet the JPEG standard's accuracy requirements;
90 the JPEG compressor or decompressor proper, and the preprocessing or
106 JPEG proper:
118 JPEG proper:
286 Here is a sketch of the logical structure of the JPEG compression library:
305 fill the subsampled-data buffer, and JPEG compression to empty it. There is
314 JPEG color space; also changes the data from pixel-interleaved layout to
332 Huffman-code optimization or emitting a multiscan JPEG file, this
335 even when the JPEG file is noninterleaved.
345 For progressive JPEG, the same DCT blocks are fed to the entropy coder
355 * Marker writing: generates JPEG markers (except for RSTn, which is emitted
358 * Data destination manager: writes the output JPEG datastream to its final
377 customization of the JPEG library. A surrounding application may override
383 The error handler and memory manager are shared by JPEG compression and
389 Here is a sketch of the logical structure of the JPEG decompression library:
404 holds the output of JPEG decompression proper. This controller's primary
413 DCT blocks at the right or bottom edge. When reading a multiscan JPEG
416 progressive JPEG.) The equivalent of one fully interleaved MCU row of
417 subsampled data is processed per call, even when the source JPEG file is
422 For progressive JPEG decoding, the coefficient controller supplies the prior
447 * Colorspace conversion: convert from JPEG color space to output color space,
461 generating 15-bit color (5 bits/primary) from JPEG's 24-bit output.
477 * Marker reading: decodes JPEG markers (except for RSTn).
479 * Data source manager: supplies the input JPEG datastream. The source
496 To support efficient incremental display of progressive JPEG files, the
506 For a progressive JPEG file, the data input processing is allowed to get
516 A full-image coefficient array is only created if the JPEG file has multiple
527 depend on any of the variables that describe the current scan in the JPEG
535 with a progressive JPEG file, nor can it predict the number of output passes
556 simplify correct rounding during downsampling, etc. The JPEG standard's
583 is helpful when dealing with noninterleaved JPEG files.
598 converted to component-wise storage inside the JPEG library. (Applications
599 that want to skip JPEG preprocessing or postprocessing will have to contend
624 quantization a la JPEG Part 3.)
633 In some applications it is desirable to use the JPEG library as an
658 codec's internal state is loaded from permanent storage (in the JPEG object
682 The JPEG marker reader is designed to cope with suspension at an arbitrary
690 The JPEG marker writer currently does *not* cope with suspension.
696 JPEG files, but we simply do not intend to support that capability with
702 The JPEG library's memory manager controls allocation and deallocation of
718 * JPOOL_IMAGE lasts until done with image (JPEG datastream)
792 JPEG mode; we may as well make it available for possible other uses.)
812 are known to the rest of the JPEG code):
853 Some JPEG files may use a DNL marker to postpone definition of the image
870 (such as two-pass color quantization or noninterleaved JPEG files) if they
893 Even if one wants piped input, buffering the first scan of the JPEG file needs