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 | |
| 4 | Version 5 24-Sep-94 |
| 5 | -------------------- |
| 6 | |
| 7 | Version 5 represents a nearly complete redesign and rewrite of the IJG |
| 8 | software. Major user-visible changes include: |
| 9 | * Automatic configuration simplifies installation for most Unix systems. |
| 10 | * A range of speed vs. image quality tradeoffs are supported. |
| 11 | This includes resizing of an image during decompression: scaling down |
| 12 | by a factor of 1/2, 1/4, or 1/8 is handled very efficiently. |
| 13 | * New programs rdjpgcom and wrjpgcom allow insertion and extraction |
| 14 | of text comments in a JPEG file. |
| 15 | |
| 16 | The application programmer's interface to the library has changed completely. |
| 17 | Notable improvements include: |
| 18 | * We have eliminated the use of callback routines for handling the |
| 19 | uncompressed image data. The application now sees the library as a |
| 20 | set of routines that it calls to read or write image data on a |
| 21 | scanline-by-scanline basis. |
| 22 | * The application image data is represented in a conventional interleaved- |
| 23 | pixel format, rather than as a separate array for each color channel. |
| 24 | This can save a copying step in many programs. |
| 25 | * The handling of compressed data has been cleaned up: the application can |
| 26 | supply routines to source or sink the compressed data. It is possible to |
| 27 | suspend processing on source/sink buffer overrun, although this is not |
| 28 | supported in all operating modes. |
| 29 | * All static state has been eliminated from the library, so that multiple |
| 30 | instances of compression or decompression can be active concurrently. |
| 31 | * JPEG abbreviated datastream formats are supported, ie, quantization and |
| 32 | Huffman tables can be stored separately from the image data. |
| 33 | * And not only that, but the documentation of the library has improved |
| 34 | considerably! |
| 35 | |
| 36 | |
| 37 | The last widely used release before the version 5 rewrite was version 4A of |
| 38 | 18-Feb-93. Change logs before that point have been discarded, since they |
| 39 | are not of much interest after the rewrite. |