Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1 | CHANGE LOG for Independent JPEG Group's JPEG software |
| 2 | |
| 3 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 4 | Version 6 2-Aug-95 |
| 5 | ------------------- |
| 6 | |
| 7 | Progressive JPEG support: library can read and write full progressive JPEG |
| 8 | files. A "buffered image" mode supports incremental decoding for on-the-fly |
| 9 | display of progressive images. Simply recompiling an existing IJG-v5-based |
| 10 | decoder with v6 should allow it to read progressive files, though of course |
| 11 | without any special progressive display. |
| 12 | |
| 13 | New "jpegtran" application performs lossless transcoding between different |
| 14 | JPEG formats; primarily, it can be used to convert baseline to progressive |
| 15 | JPEG and vice versa. In support of jpegtran, the library now allows lossless |
| 16 | reading and writing of JPEG files as DCT coefficient arrays. This ability |
| 17 | may be of use in other applications. |
| 18 | |
| 19 | Notes for programmers: |
| 20 | * We changed jpeg_start_decompress() to be able to suspend; this makes all |
| 21 | decoding modes available to suspending-input applications. However, |
| 22 | existing applications that use suspending input will need to be changed |
| 23 | to check the return value from jpeg_start_decompress(). You don't need to |
| 24 | do anything if you don't use a suspending data source. |
| 25 | * We changed the interface to the virtual array routines: access_virt_array |
| 26 | routines now take a count of the number of rows to access this time. The |
| 27 | last parameter to request_virt_array routines is now interpreted as the |
| 28 | maximum number of rows that may be accessed at once, but not necessarily |
| 29 | the height of every access. |
| 30 | |
| 31 | |
Thomas G. Lane | a8b67c4 | 1995-03-15 00:00:00 +0000 | [diff] [blame] | 32 | Version 5b 15-Mar-95 |
| 33 | --------------------- |
| 34 | |
| 35 | Correct bugs with grayscale images having v_samp_factor > 1. |
| 36 | |
| 37 | jpeg_write_raw_data() now supports output suspension. |
| 38 | |
| 39 | Correct bugs in "configure" script for case of compiling in |
| 40 | a directory other than the one containing the source files. |
| 41 | |
| 42 | Repair bug in jquant1.c: sometimes didn't use as many colors as it could. |
| 43 | |
| 44 | Borland C makefile and jconfig file work under either MS-DOS or OS/2. |
| 45 | |
| 46 | Miscellaneous improvements to documentation. |
| 47 | |
| 48 | |
Thomas G. Lane | 9ba2f5e | 1994-12-07 00:00:00 +0000 | [diff] [blame] | 49 | Version 5a 7-Dec-94 |
| 50 | -------------------- |
| 51 | |
| 52 | Changed color conversion roundoff behavior so that grayscale values are |
| 53 | represented exactly. (This causes test image files to change.) |
| 54 | |
| 55 | Make ordered dither use 16x16 instead of 4x4 pattern for a small quality |
| 56 | improvement. |
| 57 | |
| 58 | New configure script based on latest GNU Autoconf. |
| 59 | Fix configure script to handle CFLAGS correctly. |
| 60 | Rename *.auto files to *.cfg, so that configure script still works if |
| 61 | file names have been truncated for DOS. |
| 62 | |
| 63 | Fix bug in rdbmp.c: didn't allow for extra data between header and image. |
| 64 | |
| 65 | Modify rdppm.c/wrppm.c to handle 2-byte raw PPM/PGM formats for 12-bit data. |
| 66 | |
| 67 | Fix several bugs in rdrle.c. |
| 68 | |
| 69 | NEED_SHORT_EXTERNAL_NAMES option was broken. |
| 70 | |
| 71 | Revise jerror.h/jerror.c for more flexibility in message table. |
| 72 | |
| 73 | Repair oversight in jmemname.c NO_MKTEMP case: file could be there |
| 74 | but unreadable. |
| 75 | |
| 76 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 77 | Version 5 24-Sep-94 |
| 78 | -------------------- |
| 79 | |
| 80 | Version 5 represents a nearly complete redesign and rewrite of the IJG |
| 81 | software. Major user-visible changes include: |
| 82 | * Automatic configuration simplifies installation for most Unix systems. |
| 83 | * A range of speed vs. image quality tradeoffs are supported. |
| 84 | This includes resizing of an image during decompression: scaling down |
| 85 | by a factor of 1/2, 1/4, or 1/8 is handled very efficiently. |
| 86 | * New programs rdjpgcom and wrjpgcom allow insertion and extraction |
| 87 | of text comments in a JPEG file. |
| 88 | |
| 89 | The application programmer's interface to the library has changed completely. |
| 90 | Notable improvements include: |
| 91 | * We have eliminated the use of callback routines for handling the |
| 92 | uncompressed image data. The application now sees the library as a |
| 93 | set of routines that it calls to read or write image data on a |
| 94 | scanline-by-scanline basis. |
| 95 | * The application image data is represented in a conventional interleaved- |
| 96 | pixel format, rather than as a separate array for each color channel. |
| 97 | This can save a copying step in many programs. |
| 98 | * The handling of compressed data has been cleaned up: the application can |
| 99 | supply routines to source or sink the compressed data. It is possible to |
| 100 | suspend processing on source/sink buffer overrun, although this is not |
| 101 | supported in all operating modes. |
| 102 | * All static state has been eliminated from the library, so that multiple |
| 103 | instances of compression or decompression can be active concurrently. |
| 104 | * JPEG abbreviated datastream formats are supported, ie, quantization and |
| 105 | Huffman tables can be stored separately from the image data. |
| 106 | * And not only that, but the documentation of the library has improved |
| 107 | considerably! |
| 108 | |
| 109 | |
| 110 | The last widely used release before the version 5 rewrite was version 4A of |
| 111 | 18-Feb-93. Change logs before that point have been discarded, since they |
| 112 | are not of much interest after the rewrite. |