Hacktoberfest 2026：メンテナが10月に向けて印を付けた、オープンで初心者向けの issue。 Hacktoberfest の issue を見る

ImageSharp 4.1.3 misclassifies linear RGB ICC profiles as sRGB

オープン
  • 何か問題がありますか？
#3,216 コメント 0 件 リアクション 0 件 担当者 0 名 GitHub で見る

メンテナーはふだん 1 日以内に返信

まだ誰も着手していません。

評価

難易度
4/5
見積もり時間
3〜5日
初心者へのやさしさ
25/100
issue の種類
バグ
明瞭さ
おおむね明確
活発さ
活発
技術スタック
csharp
領域
backend

調査の方向性

The suspected cause is IsCanonicalSrgbMatrixTrc() in src/ImageSharp/Metadata/Profiles/ICC/IccProfile.SRGB.cs, which compares the red, green and blue curves but not whether they are the sRGB transfer function. Start with the reproduction ZIP linked in the issue and run it in both DEBUG and RELEASE to see the four failing assertions. Done means linear gamma=1 profiles are not classed as sRGB, Convert produces the expected pixel values, and Compact keeps the profile.

索引モデルが issue の本文から書いたものです。

説明

needs triage
Prerequisites
  • I have written a descriptive issue title
  • I have verified that I am running the latest version of ImageSharp
  • I have verified if the problem exist in both DEBUG and RELEASE mode
  • I have searched open and closed issues to ensure it has not already been reported
ImageSharp version

4.1.3

Other ImageSharp packages and versions

None

Environment (Operating system, version and so on)

Ubuntu WSL2, Linux x64, .NET SDK 10.0.112

.NET Framework version

.NET 10.0.12

Description

ImageSharp 4.1.3 incorrectly classifies certain linear RGB ICC profiles as canonical sRGB.

When decoding JPEG or PNG images containing a linear RGB ICC profile with sRGB primaries and gamma=1, ColorProfileHandling.Convert removes the ICC profile without converting the pixel values to sRGB.

PNG:
Actual RGB: [32,64,128]
Expected sRGB: [99,137,188]

JPEG:
Actual RGB: [40,80,120]
Expected sRGB: [110,152,182]

The expected values were independently verified using Little CMS 2.17.

ColorProfileHandling.Compact also incorrectly removes the non-sRGB ICC profile while leaving the RGB values unchanged.

The defect occurs immediately after Image.Load returns, before orientation correction, metadata removal or output encoding.

The issue reproduces identically in both DEBUG and RELEASE configurations with .NET 10.

Suspected cause:
The IsCanonicalSrgbMatrixTrc() method checks that the red, green and blue tone reproduction curves match, but does not verify that they implement the actual sRGB transfer function. Therefore, identical linear gamma=1 curves may be incorrectly classified as canonical sRGB.

Source:
https://github.com/SixLabors/ImageSharp/blob/v4.1.3/src/ImageSharp/Metadata/Profiles/ICC/IccProfile.SRGB.cs

Impact:
This defect can cause incorrect photographic colors when an ICC profile is removed without performing the necessary color transformation.

Could the maintainers confirm this issue and advise whether a fix or officially supported workaround is available for ImageSharp 4.1.x?

Steps to Reproduce

Steps to reproduce:

  1. Use SixLabors.ImageSharp 4.1.3 with .NET 10 on Linux x64 (Ubuntu WSL2).

  2. Extract the attached reproduction ZIP into a clean directory and follow its README instructions. Use a valid Six Labors license stored outside the project.

  3. Restore the locked NuGet dependencies and compile the reproduction project.

  4. Run the reproduction in both DEBUG and RELEASE configurations.

  5. The supplied synthetic JPEG and PNG images contain an ICC v4.3 RGB profile with sRGB primaries and linear gamma=1 transfer curves.

  6. Load the images using Image.Load with ColorProfileHandling.Convert, Compact and Preserve.

  7. Inspect the RGB pixel values and ICC profile immediately after decoding.

  8. Compare the results against the expected sRGB values independently verified using Little CMS 2.17.

Expected versus actual results:

PNG Convert:
Expected RGB: [99,137,188]
Actual RGB: [32,64,128]
ICC: Absent in both cases.

JPEG Convert:
Expected RGB: [110,152,182]
Actual RGB: [40,80,120]
ICC: Absent in both cases.

PNG Compact:
Expected RGB: [32,64,128]
Actual RGB: [32,64,128]
Expected ICC: Present
Actual ICC: Absent

JPEG Compact:
Expected RGB: [40,80,120]
Actual RGB: [40,80,120]
Expected ICC: Present
Actual ICC: Absent

Verification:

The defect reproduces identically in DEBUG and RELEASE.

Two Preserve control assertions pass.
Four assertions fail.
Exit code 1 is intentional because the tests detect the defect.

The problem occurs immediately after Image.Load returns, before orientation correction, metadata removal or PNG encoding.

The attached ZIP contains the minimal .NET 10 project, synthetic JPEG/PNG/ICC fixtures, instructions, expected results and SHA-256 hashes.

No license credentials, customer images or proprietary code are included.

Images

imagesharp-4.1.3-linear-icc-repro.zip

主要言語
C#
スター
8k
フォーク
904
平均マージ
15時間 39分
マージ済み PR（30日）
12

環境構築

はじめの一歩

  1. issue を最後まで読み、次にプロジェクトのコントリビューションガイドを読みます。
  2. 着手することを issue にコメントします — 二人が同じ作業をするのを防げます。
  3. リポジトリをフォークし、ブランチを切って変更します。
  4. issue 番号を参照したプルリクエストを送ります。

SixLabors/ImageSharp のほかの issue

SixLabors/ImageSharp の issue をすべて見る

似ている issue

C# の issue をもっと見る

新しい issue をメールで受け取る

初心者向けの GitHub issue を短くまとめたダイジェスト。