[STR Closed w/o Resolution] Link: http://www.fltk.org/str.php?L2193 Version: 1.1.9 Fix Version: Will Not Fix
Michael Sweet wrote: > Fix Version: Will Not Fix Are you sure? > According to the JPEG File Interchange Format (JFIF) spec, JFIF files (what > are provided as .jpg or .jpeg) MUST begin with an APPn chunk. See: > > http://www.w3.org/Graphics/JPEG/jfif3.pdf I read this so that JFIF is a special case (subset) of the JPEG specification. > Specifically: > > The syntax of a JFIF file conforms to the syntax for interchange > format defined in Annex B of ISO DIS 10918-1. In addition, a JFIF .....................................................^^^^^^^^^^^^ > file uses APP0 marker segments and constrains certain parameters in .........................................^^^^^^^^^^ > the frame header as defined below. > > So, a file starting with a JPEG comment block does not conform to the JFIF > spec and cannot be auto-detected as a JPEG file. If we do only support the JFIF *subset* ... Should we? >From the same PDF file: "The JPEG File Interchange Format is entirely compatible with the standard JPEG interchange format; the only additional requirement is the mandatory presence of the APP0 marker right after the SOI marker." <End of citation.> "The only additional requirement" means for me that this is a requirement only for JFIF, but not for JPEG itself. If the intention in the original code was to test for JFIF, then it should have checked for exactly four bytes and the APP0 marker in the fourth byte (and maybe the following "JFIF\0" as well) and not a range. If there are no other reasons, then IMHO the proposed patch would be okay, and I suggest to use it for FLTK 1.1 and 1.3. And, BTW, it works, and I can load the example JPEG file ;-) Link: http://www.fltk.org/str.php?L2193 Version: 1.1.9 Fix Version: Will Not Fix _______________________________________________ fltk-bugs mailing list [email protected] http://lists.easysw.com/mailman/listinfo/fltk-bugs
