From 2eb03b004915688d3fc8e41a9429494a01b57acf Mon Sep 17 00:00:00 2001
From: Lovell Fuller <github@lovell.info>
Date: Sun, 11 Aug 2024 09:44:53 +0100
Subject: [PATCH] Ensure keepIccProfile avoids ICC transform #4186

---
 docs/changelog.md          |   3 +++
 src/pipeline.cc            |   1 +
 test/fixtures/index.js     |   1 +
 test/fixtures/prophoto.png | Bin 0 -> 556 bytes
 test/unit/metadata.js      |  11 +++++++++++
 5 files changed, 16 insertions(+)
 create mode 100644 test/fixtures/prophoto.png

diff --git a/docs/changelog.md b/docs/changelog.md
index aa78725ab..b198fab7c 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -29,6 +29,9 @@ Requires libvips v8.15.2
   [#4172](https://github.com/lovell/sharp/pull/4172)
   [@marcosc90](https://github.com/marcosc90)
 
+* Ensure `keepIccProfile` avoids colour transformation where possible.
+  [#4186](https://github.com/lovell/sharp/issues/4186)
+
 ### v0.33.4 - 16th May 2024
 
 * Remove experimental status from `pipelineColourspace`.
diff --git a/src/pipeline.cc b/src/pipeline.cc
index fafd695ca..ac5ead01e 100644
--- a/src/pipeline.cc
+++ b/src/pipeline.cc
@@ -325,6 +325,7 @@ class PipelineWorker : public Napi::AsyncWorker {
       if ((baton->keepMetadata & VIPS_FOREIGN_KEEP_ICC) && baton->withIccProfile.empty()) {
         // Cache input profile for use with output
         inputProfile = sharp::GetProfile(image);
+        baton->input->ignoreIcc = true;
       }
       char const *processingProfile = image.interpretation() == VIPS_INTERPRETATION_RGB16 ? "p3" : "srgb";
       if (
diff --git a/test/fixtures/index.js b/test/fixtures/index.js
index a791ac7e8..e4b8e266e 100644
--- a/test/fixtures/index.js
+++ b/test/fixtures/index.js
@@ -99,6 +99,7 @@ module.exports = {
   inputPngTrimSpecificColour16bit: getPath('Flag_of_the_Netherlands-16bit.png'), // convert Flag_of_the_Netherlands.png -depth 16 Flag_of_the_Netherlands-16bit.png
   inputPngTrimSpecificColourIncludeAlpha: getPath('Flag_of_the_Netherlands-alpha.png'), // convert Flag_of_the_Netherlands.png -alpha set -background none -channel A -evaluate multiply 0.5 +channel Flag_of_the_Netherlands-alpha.png
   inputPngUint32Limit: getPath('65536-uint32-limit.png'), // https://alexandre.alapetite.fr/doc-alex/large-image/
+  inputPngWithProPhotoProfile: getPath('prophoto.png'),
 
   inputWebP: getPath('4.webp'), // http://www.gstatic.com/webp/gallery/4.webp
   inputWebPWithTransparency: getPath('5_webp_a.webp'), // http://www.gstatic.com/webp/gallery3/5_webp_a.webp
diff --git a/test/fixtures/prophoto.png b/test/fixtures/prophoto.png
new file mode 100644
index 0000000000000000000000000000000000000000..e01fcb02a05ac9a422cf97d89ce52b37ee6b0123
GIT binary patch
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diff --git a/test/unit/metadata.js b/test/unit/metadata.js
index 417871299..83fddf30f 100644
--- a/test/unit/metadata.js
+++ b/test/unit/metadata.js
@@ -601,6 +601,17 @@ describe('Image metadata', function () {
     assert.strictEqual(description, 'Generic RGB Profile');
   });
 
+  it('keep existing ICC profile, avoid colour transform', async () => {
+    const [r, g, b] = await sharp(fixtures.inputPngWithProPhotoProfile)
+      .keepIccProfile()
+      .raw()
+      .toBuffer();
+
+    assert.strictEqual(r, 131);
+    assert.strictEqual(g, 141);
+    assert.strictEqual(b, 192);
+  });
+
   it('keep existing CMYK ICC profile', async () => {
     const data = await sharp(fixtures.inputJpgWithCmykProfile)
       .pipelineColourspace('cmyk')