JXL->JXL processing (to remove alpha channel) drops color profile #8022
Description
ImageMagick version
7.1.1-44
Operating system
Linux
Operating system, version and so on
Fedora 41 x86_64
Description
The Fedora 42 background images are going to be distributed in JXL format instead of the traditional PNG. Due to the limitations of the GNOME background system's timed-transition image blending, it's necessary that background images be stripped of their alpha channel before installation. We've been accomplishing that with a magick -alpha off command, which works fine on PNG images.
It works fairly well on JXL images as well (with an added -quality 100), but the output image no longer carries the same color profile as the input image.
Steps to Reproduce
1. Unzip and examine the original file:
$ unzip f42-01-day.zip
Archive: f42-01-day.zip
inflating: f42-01-day.jxl
$ identify -verbose f42-01-day.jxl
Image:
Filename: f42-01-day.jxl
Permissions: rw-r--r--
Format: JXL (JPEG XL (ISO/IEC 18181))
Mime type: image/jxl
Class: DirectClass
Geometry: 4032x3024+0+0
Units: Undefined
Colorspace: sRGB
Type: TrueColorAlpha
Base type: Undefined
Endianness: Undefined
Depth: 8-bit
Channels: 4.0
Channel depth:
Red: 8-bit
Green: 8-bit
Blue: 8-bit
Alpha: 1-bit
Channel statistics:
Pixels: 12192768
Red:
min: 12 (0.0470588)
max: 214 (0.839216)
mean: 126.731 (0.496982)
median: 133 (0.521569)
standard deviation: 43.3644 (0.170056)
kurtosis: -0.324868
skewness: 0.0404497
entropy: 0.749915
Green:
min: 5 (0.0196078)
max: 224 (0.878431)
mean: 137.296 (0.538416)
median: 142 (0.556863)
standard deviation: 47.5222 (0.186362)
kurtosis: -0.608794
skewness: -0.11526
entropy: 0.76154
Blue:
min: 5 (0.0196078)
max: 221 (0.866667)
mean: 105.595 (0.414096)
median: 90 (0.352941)
standard deviation: 54.5139 (0.21378)
kurtosis: -0.439243
skewness: 0.766023
entropy: 0.752578
Alpha:
min: 255 (1)
max: 255 (1)
mean: 255 (1)
median: 255 (1)
standard deviation: 0 (0)
kurtosis: 0
skewness: 0
entropy: 0
Image statistics:
Overall:
min: 5 (0.0196078)
max: 255 (1)
mean: 156.155 (0.612374)
median: 155 (0.607843)
standard deviation: 36.3501 (0.14255)
kurtosis: -0.343226
skewness: 0.172803
entropy: 0.566008
Rendering intent: Perceptual
Gamma: 0.454545
Chromaticity:
red primary: (0.64,0.33,0.03)
green primary: (0.3,0.6,0.1)
blue primary: (0.15,0.06,0.79)
white point: (0.3127,0.329,0.3583)
Matte color: grey74
Background color: white
Border color: srgb(223,223,223)
Transparent color: black
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 4032x3024+0+0
Dispose: Undefined
Iterations: 0
Compression: Undefined
Orientation: TopLeft
Profiles:
Profile-icc: 9080 bytes
Properties:
date:create: 2025-03-11T23:48:07+00:00
date:modify: 2025-03-11T08:05:06+00:00
date:timestamp: 2025-03-11T23:48:55+00:00
icc:copyright: Copyright 2015, Elle Stone (website: http://ninedegreesbelow.com/; email: [email protected]). This ICC profile is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License (https://creativecommons.org/licenses/by-sa/3.0/legalcode).
icc:description: sRGB-elle-V2-srgbtrc.icc
mime:type: image/jxl
signature: 6a090391cc3d126be6a5807503aeef4cfddce0c527120cbf76252cdaa7e4ddbd
Artifacts:
verbose: true
Tainted: False
Filesize: 1.93684MiB
Number pixels: 12.1928M
Pixel cache type: Memory
Pixels per second: 13.1612MP
User time: 2.440u
Elapsed time: 0:01.926
Version: ImageMagick 7.1.1-44 Q16-HDRI x86_64 22688 https://imagemagick.orgThe original image contains a 9k color profile, sRGB-elle-V2-srgbtrc.icc.
2. Process the image using ImageMagick to remove alpha channel
$ magick f42-01-day.jxl -quality 100 -alpha off f42-01-day_noalpha.jxl3. Examine the output file
$ identify -verbose f42-01-day_noalpha.jxl
Image:
Filename: f42-01-day_noalpha.jxl
Permissions: rw-r--r--
Format: JXL (JPEG XL (ISO/IEC 18181))
Mime type: image/jxl
Class: DirectClass
Geometry: 4032x3024+0+0
Units: Undefined
Colorspace: sRGB
Type: TrueColor
Base type: Undefined
Endianness: Undefined
Depth: 8-bit
Channels: 3.0
Channel depth:
Red: 8-bit
Green: 8-bit
Blue: 8-bit
Channel statistics:
Pixels: 12192768
Red:
min: 12 (0.0470588)
max: 214 (0.839216)
mean: 126.731 (0.496982)
median: 133 (0.521569)
standard deviation: 43.3644 (0.170056)
kurtosis: -0.324868
skewness: 0.0404497
entropy: 0.749915
Green:
min: 5 (0.0196078)
max: 224 (0.878431)
mean: 137.296 (0.538416)
median: 142 (0.556863)
standard deviation: 47.5222 (0.186362)
kurtosis: -0.608794
skewness: -0.11526
entropy: 0.76154
Blue:
min: 5 (0.0196078)
max: 221 (0.866667)
mean: 105.595 (0.414096)
median: 90 (0.352941)
standard deviation: 54.5139 (0.21378)
kurtosis: -0.439243
skewness: 0.766023
entropy: 0.752578
Image statistics:
Overall:
min: 5 (0.0196078)
max: 224 (0.878431)
mean: 123.207 (0.483165)
median: 121.667 (0.477124)
standard deviation: 48.4668 (0.190066)
kurtosis: -0.457635
skewness: 0.230404
entropy: 0.754678
Rendering intent: Relative
Gamma: 0.454545
Chromaticity:
red primary: (0.64,0.33,0.03)
green primary: (0.3,0.6,0.1)
blue primary: (0.15,0.06,0.79)
white point: (0.3127,0.329,0.3583)
Matte color: grey74
Background color: white
Border color: srgb(223,223,223)
Transparent color: black
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 4032x3024+0+0
Dispose: Undefined
Iterations: 0
Compression: Undefined
Orientation: TopLeft
Profiles:
Profile-icc: 536 bytes
Properties:
date:create: 2025-03-11T23:50:54+00:00
date:modify: 2025-03-11T23:50:54+00:00
date:timestamp: 2025-03-11T23:51:34+00:00
icc:copyright: CC0
icc:description: RGB_D65_SRG_Rel_SRG
mime:type: image/jxl
signature: bb19320a637ffbb342d9fcf381ea825659dbf8c10ac02fd768311252f2a68c33
Artifacts:
verbose: true
Tainted: False
Filesize: 1.9296MiB
Number pixels: 12.1928M
Pixel cache type: Memory
Pixels per second: 14.5702MP
User time: 2.270u
Elapsed time: 0:01.836
Version: ImageMagick 7.1.1-44 Q16-HDRI x86_64 22688 https://imagemagick.orgThe image no longer has an alpha channel (that's good!), but has lost the ICC profile and other metadata.
Delegate information:
$ magick -list format|grep jxl
JXL* JXL rw+ JPEG XL (ISO/IEC 18181) (libjxl 0.10.4)Images
Here's the first of the upcoming Fedora 42 background images, in source JXL format (with color profile):