Bug#1107145: Attempting to export an 8 bit linear image results in a 16 bit linear file instead

[Michael Deegan]

Package: gimp
Version: 3.0.2-3.1
Severity: normal

When exporting TIFFs from the attached (32 bit linear float) image after
fiddling with the pixel format, I noticed that the 8 bit linear integer
image is twice the size it's supposed to be, because it's actually 16 bit:

    r_6010912-6010991-raw_stacked-linear-float32.tiff TIFF 640x360 640x360+0+0 32-bit sRGB 2.64045MiB 0.000u 0:00.000
    r_6010912-6010991-raw_stacked-linear-int16.tiff TIFF 640x360 640x360+0+0 16-bit sRGB 1.32209MiB 0.000u 0:00.000
    r_6010912-6010991-raw_stacked-linear-int8.tiff TIFF 640x360 640x360+0+0 16-bit sRGB 1.32209MiB 0.000u 0:00.000
    r_6010912-6010991-raw_stacked-nonlinear-float32.tiff TIFF 640x360 640x360+0+0 32-bit sRGB 2.64045MiB 0.000u 0:00.000
    r_6010912-6010991-raw_stacked-nonlinear-int16.tiff TIFF 640x360 640x360+0+0 16-bit sRGB 1.32209MiB 0.000u 0:00.000
    r_6010912-6010991-raw_stacked-nonlinear-int8.tiff TIFF 640x360 640x360+0+0 8-bit sRGB 695108B 0.000u 0:00.000

Expected results: exporting an 8-bit image should result in an 8-bit TIFF.

-- System Information:
Debian Release: 13.0
  APT prefers testing-debug
  APT policy: (500, 'testing-debug'), (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable-debug'), (500, 'testing'), (500, 'stable'), (400, 'unstable-debug'), (400, 'unstable'), (1, 'experimental-debug'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 6.12.22-amd64 (SMP w/12 CPU threads; PREEMPT)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), LANGUAGE=en_AU:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gimp depends on:
ii  gimp-data            3.0.2-3.1
ii  gir1.2-gimp-3.0      3.0.2-3.1
ii  graphviz             2.42.4-3
ii  libaa1               1.4p5-51.1+b1
ii  libappstream-glib8   0.8.3-1
ii  libarchive13t64      3.7.4-3
ii  libasound2t64        1.2.14-1
ii  libbabl-0.1-0        1:0.1.112-1
ii  libbz2-1.0           1.0.8-6
ii  libc6                2.41-8
ii  libcairo2            1.18.4-1+b1
ii  libcfitsio10t64      4.6.2-2
ii  libfontconfig1       2.15.0-2.3
ii  libfreetype6         2.13.3+dfsg-1
ii  libgcc-s1            14.2.0-19
ii  libgdk-pixbuf-2.0-0  2.42.12+dfsg-2
ii  libgegl-0.4-0t64     1:0.4.58-2
ii  libgexiv2-2          0.14.3-1+b1
ii  libgimp-3.0-0        3.0.2-3.1
ii  libglib2.0-0t64      2.84.1-2
ii  libgomp1             14.2.0-19
ii  libgs10              10.05.1~dfsg-1
ii  libgtk-3-0t64        3.24.49-3
ii  libgudev-1.0-0       238-6
ii  libharfbuzz0b        10.2.0-1+b1
ii  libheif1             1.19.8-1
ii  libjpeg62-turbo      1:2.1.5-4
ii  libjson-glib-1.0-0   1.10.6+ds-2
ii  libjxl0.11           0.11.1-4
ii  liblcms2-2           2.16-2
ii  liblzma5             5.8.1-1
ii  libmypaint-1.5-1     1.6.0-4
ii  libopenexr-3-1-30    3.1.13-2
ii  libopenjp2-7         2.5.3-2
ii  libpango-1.0-0       1.56.3-1
ii  libpangocairo-1.0-0  1.56.3-1
ii  libpangoft2-1.0-0    1.56.3-1
ii  libpng16-16t64       1.6.48-1
ii  libpoppler-glib8t64  25.03.0-4
ii  librsvg2-2           2.60.0+dfsg-1
ii  librsvg2-common      2.60.0+dfsg-1
ii  libstdc++6           14.2.0-19
ii  libtiff6             4.7.0-3
ii  libwebp7             1.5.0-0.1
ii  libwebpdemux2        1.5.0-0.1
ii  libwebpmux3          1.5.0-0.1
ii  libwmf-0.2-7         0.2.13-1.1+b3
ii  libwmflite-0.2-7     0.2.13-1.1+b3
ii  libx11-6             2:1.8.12-1
ii  libxcursor1          1:1.2.3-1
ii  libxext6             2:1.3.4-1+b3
ii  libxfixes3           1:6.0.0-2+b4
ii  libxmu6              2:1.1.3-3+b4
ii  libxpm4              1:3.5.17-1+b3
ii  python3-gi           3.50.0-4+b1
ii  xdg-utils            1.2.1-2
ii  zlib1g               1:1.3.dfsg+really1.3.1-1+b1

Versions of packages gimp recommends:
ii  ghostscript  10.05.1~dfsg-1

Versions of packages gimp suggests:
ii  gimp-data-extras          1:2.0.4-0.2
ii  gimp-help-en [gimp-help]  3.0.0-4
ii  gvfs-backends             1.57.2-2
ii  python3                   3.13.3-1

-- debconf-show failed

-MD

-- 
-----------------------------------------------------------------------------
Michael Deegan               Hugaholic              https://www.deegan.id.au/
------------------------  Jung, zr jbeel?  ----------------------------------
-------------- next part --------------
A non-text attachment was scrubbed...
Name: r_6010912-6010991-raw_stacked.xcf
Type: image/x-xcf
Size: 2116932 bytes
Desc: not available
URL: <http://alioth-lists.debian.net/pipermail/pkg-gnome-maintainers/attachments/20250602/3beb7e63/attachment-0001.bin>