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fix(webp): Missing oiio:UnassociatedAlpha on input #5020

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Merged
lgritz merged 1 commit into from
Jan 29, 2026
Merged

fix(webp): Missing oiio:UnassociatedAlpha on input #5020

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5 changes: 4 additions & 1 deletion src/webp.imageio/webpinput.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -214,8 +214,11 @@ WebpInput::open(const std::string& name, ImageSpec& spec,
// Make space for the decoded image
m_decoded_image.reset(new uint8_t[m_spec.image_bytes()]);

if (config.get_int_attribute("oiio:UnassociatedAlpha", 0) == 1)
if (config.get_int_attribute("oiio:UnassociatedAlpha", 0) == 1) {
m_keep_unassociated_alpha = true;
if (m_spec.alpha_channel != -1)
m_spec.attribute("oiio:UnassociatedAlpha", 1);
}

seek_subimage(0, 0);
spec = m_spec;
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6 changes: 6 additions & 0 deletions testsuite/webp/ref/out-webp1.1.txt
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Expand Up @@ -18,3 +18,9 @@ Reading ../oiio-images/webp/4.webp
SHA-1: 8F42E3DCCE6FE15146BA06C440C15B7831F60572
channel list: R, G, B
oiio:ColorSpace: "srgb_rec709_scene"
Reading rgba.webp
rgba.webp : 64 x 64, 4 channel, uint8 webp
SHA-1: 897256B6709E1A4DA9DABA92B6BDE39CCFCCD8C1
channel list: R, G, B, A
oiio:ColorSpace: "srgb_rec709_scene"
oiio:UnassociatedAlpha: 1
3 changes: 3 additions & 0 deletions testsuite/webp/run.py
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Expand Up @@ -11,3 +11,6 @@
# a lossy format and is not stable under the round trip
# command += rw_command (OIIO_TESTSUITE_IMAGEDIR, f,
# extraargs='-attrib compression lossless')

command += oiiotool ("--create 64x64 4 -o rgba.webp")
command += info_command ("rgba.webp", "--iconfig oiio:UnassociatedAlpha 1", safematch=True)
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