Package: file Version: 1:5.39-3 Severity: normal Dear Maintainer,
Currently file behavior is as follow (on the gunzip'ed attached file): Input files: % file black*.j* black.j2k: JPEG 2000 codestream black_jfif.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, baseline, precision 8, 512x512, components 1 black.jp2: JPEG 2000 Part 1 (JP2) black_noAPP0.jpg: JPEG image data, baseline, precision 8, 512x512, components 1 leads to the following mime-type behavior: % file --mime-type black*.j* black.j2k: application/octet-stream black_jfif.jpg: image/jpeg black.jp2: image/jp2 black_noAPP0.jpg: image/jpeg One can verify that removing the APP0 marker entirely does not affect file --mime-type behavior. The mime-type reported is image/jpeg. One can noticed that in the case of multiple components there could be an issue since no color space information would be carried in one such file (no APP0). Consider now the behavior for JPEG 2000 codestream. file --mime-type returns "application/octet-stream". This can clearly be improved. JPEG 2000 codestream while not mainstream can be found encapsulated in PDF 1.7 document. It would make sense for `file` to report in one such case: % file --mime-type black.j2k black.j2k: image/jp2 The online documentation: * https://www.iana.org/assignments/media-types/image/jp2 states: [...] Magic number(s): 12 byte string: X'0000 000C 6A50 2020 0D0A 870A' (for all JPEG-2000 family files) [...] The above is quite clear for black.jp2, but the interpretation should not be too strict. And indeed mime-type for black.j2k should also be 'image/jp2'. Thanks for consideration -- System Information: Debian Release: 11.1 APT prefers stable-updates APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable-debug'), (500, 'proposed-updates-debug'), (500, 'stable') Architecture: amd64 (x86_64) Foreign Architectures: i386 Kernel: Linux 5.14.0-0.bpo.2-amd64 (SMP w/8 CPU threads) Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages file depends on: ii libc6 2.31-13+deb11u2 ii libmagic1 1:5.39-3 file recommends no packages. file suggests no packages. -- no debconf information
black.j2k.gz
Description: application/gzip
black_jfif.jpg.gz
Description: application/gzip
black.jp2.gz
Description: application/gzip
black_noAPP0.jpg.gz
Description: application/gzip
