Lines Matching full:jpeg
1 IJG JPEG LIBRARY: SYSTEM ARCHITECTURE
4 This file is part of the Independent JPEG Group's software.
8 This file provides an overview of the architecture of the IJG JPEG software;
13 We assume that the reader is already somewhat familiar with the JPEG standard.
14 The README file includes references for learning about JPEG. The file
19 In this document, JPEG-specific terminology follows the JPEG standard:
38 * A subroutine library for JPEG compression and decompression.
40 JFIF JPEG files to and from several other image formats.
45 We desire the library to be capable of supporting all JPEG baseline, extended
49 The library does not support the lossless (spatial) JPEG process. Lossless
50 JPEG shares little or no code with lossy JPEG, and would normally be used
52 We feel that lossless JPEG is better handled by a separate library.
54 Within these limits, any set of compression parameters allowed by the JPEG
63 For legal reasons, JPEG arithmetic coding is not currently supported, but
66 By itself, the library handles only interchange JPEG datastreams --- in
68 surrounding code to process interchange or abbreviated JPEG datastreams that
70 library to implement JPEG compression within the TIFF file format.)
73 JPEG standard but is necessary for typical applications of JPEG. These
74 functions preprocess the image before JPEG compression or postprocess it after
78 A wide range of quality vs. speed tradeoffs are possible in JPEG processing,
84 low-quality modes may not meet the JPEG standard's accuracy requirements;
109 the JPEG compressed datastream must ultimately appear on external storage as a
121 the JPEG compressor or decompressor proper, and the preprocessing or
123 image data that the official JPEG spec regards as its input or output: this
137 JPEG proper:
149 JPEG proper:
175 as a preprocessing/postprocessing function, even though the JPEG spec includes
317 Here is a sketch of the logical structure of the JPEG compression library:
336 fill the subsampled-data buffer, and JPEG compression to empty it. There is
345 JPEG color space; also changes the data from pixel-interleaved layout to
363 Huffman-code optimization or emitting a multiscan JPEG file, this
366 even when the JPEG file is noninterleaved.
376 For progressive JPEG, the same DCT blocks are fed to the entropy coder
386 * Marker writing: generates JPEG markers (except for RSTn, which is emitted
389 * Data destination manager: writes the output JPEG datastream to its final
407 customization of the JPEG library. A surrounding application may override
413 The error handler and memory manager are shared by JPEG compression and
419 Here is a sketch of the logical structure of the JPEG decompression library:
434 holds the output of JPEG decompression proper. This controller's primary
443 DCT blocks at the right or bottom edge. When reading a multiscan JPEG
446 progressive JPEG.) The equivalent of one fully interleaved MCU row of
447 subsampled data is processed per call, even when the source JPEG file is
452 For progressive JPEG decoding, the coefficient controller supplies the prior
477 * Colorspace conversion: convert from JPEG color space to output color space,
491 generating 15-bit color (5 bits/primary) from JPEG's 24-bit output.
507 * Marker reading: decodes JPEG markers (except for RSTn).
509 * Data source manager: supplies the input JPEG datastream. The source
526 To support efficient incremental display of progressive JPEG files, the
536 For a progressive JPEG file, the data input processing is allowed to get
546 A full-image coefficient array is only created if the JPEG file has multiple
557 depend on any of the variables that describe the current scan in the JPEG
565 with a progressive JPEG file, nor can it predict the number of output passes
590 simplify correct rounding during downsampling, etc. The JPEG standard's
618 is helpful when dealing with noninterleaved JPEG files.
633 converted to component-wise storage inside the JPEG library. (Applications
634 that want to skip JPEG preprocessing or postprocessing will have to contend
659 quantization a la JPEG Part 3.)
679 In some applications it is desirable to use the JPEG library as an
704 codec's internal state is loaded from permanent storage (in the JPEG object
728 The JPEG marker reader is designed to cope with suspension at an arbitrary
736 The JPEG marker writer currently does *not* cope with suspension. I feel that
741 trailer.) This would not work for writing multi-scan JPEG files, but
747 The JPEG library's memory manager controls allocation and deallocation of
763 * JPOOL_IMAGE lasts until done with image (JPEG datastream)
838 JPEG mode; we may as well make it available for possible other uses.)
858 are known to the rest of the JPEG code):
901 Some JPEG files may use a DNL marker to postpone definition of the image
918 (such as two-pass color quantization or noninterleaved JPEG files) if they
941 Even if one wants piped input, buffering the first scan of the JPEG file needs
