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 | 489583f | 1996-02-07 00:00:00 +0000 | [diff] [blame^] | 4 | Version 6a 7-Feb-96 |
| 5 | -------------------- |
| 6 | |
| 7 | Library initialization sequence modified to detect version mismatches |
| 8 | and struct field packing mismatches between library and calling application. |
| 9 | This change requires applications to be recompiled, but does not require |
| 10 | any application source code change. |
| 11 | |
| 12 | All routine declarations changed to the style "GLOBAL(type) name ...", |
| 13 | that is, GLOBAL, LOCAL, METHODDEF, EXTERN are now macros taking the |
| 14 | routine's return type as an argument. This makes it possible to add |
| 15 | Microsoft-style linkage keywords to all the routines by changing just |
| 16 | these macros. Note that any application code that was using these macros |
| 17 | will have to be changed. |
| 18 | |
| 19 | DCT coefficient quantization tables are now stored in normal array order |
| 20 | rather than zigzag order. Application code that calls jpeg_add_quant_table, |
| 21 | or otherwise manipulates quantization tables directly, will need to be |
| 22 | changed. If you need to make such code work with either older or newer |
| 23 | versions of the library, a test like "#if JPEG_LIB_VERSION >= 61" is |
| 24 | recommended. |
| 25 | |
| 26 | djpeg's trace capability now dumps DQT tables in natural order, not zigzag |
| 27 | order. This allows the trace output to be made into a "-qtables" file |
| 28 | more easily. |
| 29 | |
| 30 | New system-dependent memory manager module for use on Apple Macintosh. |
| 31 | |
| 32 | Fix bug in cjpeg's -smooth option: last one or two scanlines would be |
| 33 | duplicates of the prior line unless the image height mod 16 was 1 or 2. |
| 34 | |
| 35 | Repair minor problems in VMS, BCC, MC6 makefiles. |
| 36 | |
| 37 | New configure script based on latest GNU Autoconf. |
| 38 | |
| 39 | Correct the list of include files needed by MetroWerks C for ccommand(). |
| 40 | |
| 41 | Numerous small documentation updates. |
| 42 | |
| 43 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 44 | Version 6 2-Aug-95 |
| 45 | ------------------- |
| 46 | |
| 47 | Progressive JPEG support: library can read and write full progressive JPEG |
| 48 | files. A "buffered image" mode supports incremental decoding for on-the-fly |
| 49 | display of progressive images. Simply recompiling an existing IJG-v5-based |
| 50 | decoder with v6 should allow it to read progressive files, though of course |
| 51 | without any special progressive display. |
| 52 | |
| 53 | New "jpegtran" application performs lossless transcoding between different |
| 54 | JPEG formats; primarily, it can be used to convert baseline to progressive |
| 55 | JPEG and vice versa. In support of jpegtran, the library now allows lossless |
| 56 | reading and writing of JPEG files as DCT coefficient arrays. This ability |
| 57 | may be of use in other applications. |
| 58 | |
| 59 | Notes for programmers: |
| 60 | * We changed jpeg_start_decompress() to be able to suspend; this makes all |
| 61 | decoding modes available to suspending-input applications. However, |
| 62 | existing applications that use suspending input will need to be changed |
| 63 | to check the return value from jpeg_start_decompress(). You don't need to |
| 64 | do anything if you don't use a suspending data source. |
| 65 | * We changed the interface to the virtual array routines: access_virt_array |
| 66 | routines now take a count of the number of rows to access this time. The |
| 67 | last parameter to request_virt_array routines is now interpreted as the |
| 68 | maximum number of rows that may be accessed at once, but not necessarily |
| 69 | the height of every access. |
| 70 | |
| 71 | |
Thomas G. Lane | a8b67c4 | 1995-03-15 00:00:00 +0000 | [diff] [blame] | 72 | Version 5b 15-Mar-95 |
| 73 | --------------------- |
| 74 | |
| 75 | Correct bugs with grayscale images having v_samp_factor > 1. |
| 76 | |
| 77 | jpeg_write_raw_data() now supports output suspension. |
| 78 | |
| 79 | Correct bugs in "configure" script for case of compiling in |
| 80 | a directory other than the one containing the source files. |
| 81 | |
| 82 | Repair bug in jquant1.c: sometimes didn't use as many colors as it could. |
| 83 | |
| 84 | Borland C makefile and jconfig file work under either MS-DOS or OS/2. |
| 85 | |
| 86 | Miscellaneous improvements to documentation. |
| 87 | |
| 88 | |
Thomas G. Lane | 9ba2f5e | 1994-12-07 00:00:00 +0000 | [diff] [blame] | 89 | Version 5a 7-Dec-94 |
| 90 | -------------------- |
| 91 | |
| 92 | Changed color conversion roundoff behavior so that grayscale values are |
| 93 | represented exactly. (This causes test image files to change.) |
| 94 | |
| 95 | Make ordered dither use 16x16 instead of 4x4 pattern for a small quality |
| 96 | improvement. |
| 97 | |
| 98 | New configure script based on latest GNU Autoconf. |
| 99 | Fix configure script to handle CFLAGS correctly. |
| 100 | Rename *.auto files to *.cfg, so that configure script still works if |
| 101 | file names have been truncated for DOS. |
| 102 | |
| 103 | Fix bug in rdbmp.c: didn't allow for extra data between header and image. |
| 104 | |
| 105 | Modify rdppm.c/wrppm.c to handle 2-byte raw PPM/PGM formats for 12-bit data. |
| 106 | |
| 107 | Fix several bugs in rdrle.c. |
| 108 | |
| 109 | NEED_SHORT_EXTERNAL_NAMES option was broken. |
| 110 | |
| 111 | Revise jerror.h/jerror.c for more flexibility in message table. |
| 112 | |
| 113 | Repair oversight in jmemname.c NO_MKTEMP case: file could be there |
| 114 | but unreadable. |
| 115 | |
| 116 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 117 | Version 5 24-Sep-94 |
| 118 | -------------------- |
| 119 | |
| 120 | Version 5 represents a nearly complete redesign and rewrite of the IJG |
| 121 | software. Major user-visible changes include: |
| 122 | * Automatic configuration simplifies installation for most Unix systems. |
| 123 | * A range of speed vs. image quality tradeoffs are supported. |
| 124 | This includes resizing of an image during decompression: scaling down |
| 125 | by a factor of 1/2, 1/4, or 1/8 is handled very efficiently. |
| 126 | * New programs rdjpgcom and wrjpgcom allow insertion and extraction |
| 127 | of text comments in a JPEG file. |
| 128 | |
| 129 | The application programmer's interface to the library has changed completely. |
| 130 | Notable improvements include: |
| 131 | * We have eliminated the use of callback routines for handling the |
| 132 | uncompressed image data. The application now sees the library as a |
| 133 | set of routines that it calls to read or write image data on a |
| 134 | scanline-by-scanline basis. |
| 135 | * The application image data is represented in a conventional interleaved- |
| 136 | pixel format, rather than as a separate array for each color channel. |
| 137 | This can save a copying step in many programs. |
| 138 | * The handling of compressed data has been cleaned up: the application can |
| 139 | supply routines to source or sink the compressed data. It is possible to |
| 140 | suspend processing on source/sink buffer overrun, although this is not |
| 141 | supported in all operating modes. |
| 142 | * All static state has been eliminated from the library, so that multiple |
| 143 | instances of compression or decompression can be active concurrently. |
| 144 | * JPEG abbreviated datastream formats are supported, ie, quantization and |
| 145 | Huffman tables can be stored separately from the image data. |
| 146 | * And not only that, but the documentation of the library has improved |
| 147 | considerably! |
| 148 | |
| 149 | |
| 150 | The last widely used release before the version 5 rewrite was version 4A of |
| 151 | 18-Feb-93. Change logs before that point have been discarded, since they |
| 152 | are not of much interest after the rewrite. |