Verify.ImageSharp

Extends Verify to allow verification of documents via ImageSharp.

See Milestones for release notes.

Sponsors

Entity Framework Extensions

Entity Framework Extensions is a major sponsor and is proud to contribute to the development this project.

Developed using JetBrains IDEs

NuGet

• https://nuget.org/packages/Verify.ImageSharp

Usage

[ModuleInitializer]
public static void Init() =>
    VerifyImageSharp.Initialize();

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Verify a file

[Test]
public Task VerifyImageFile() =>
    VerifyFile("sample.jpg");

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[Test]
public Task VerifyImageFileWithCustomEncoder() =>
    VerifyFile("sample.jpg")
        .EncodeAsPng();

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Two files are produced

Info file:

Samples.VerifyImageFile.verified.txt

{
  Width: 1599,
  Height: 1066,
  HorizontalResolution: 1.0,
  VerticalResolution: 1.0
}

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Image file:

Samples.VerifyImageFile.verified.jpg

Verify an SixLabors.ImageSharp.Image

An instance if an SixLabors.ImageSharp.Image can be verified using the following:

[Test]
public Task VerifyImage()
{
    var image = new Image<Rgba32>(11, 11)
    {
        [5, 5] = Rgba32.ParseHex("#0000FF")
    };
    return Verify(image);
}

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SSIM Image Comparison

By default, image comparison is byte-exact. To tolerate minor rendering differences (anti-aliasing, font hinting, subpixel rendering), enable SSIM (Structural Similarity Index) comparison by passing a threshold to Initialize:

[ModuleInitializer]
public static void Init() =>
    VerifyImageSharp.Initialize(ssimThreshold: 0.999);

SSIM returns a value between 0.0 (completely different) and 1.0 (identical). Images with an SSIM at or above the threshold are considered equal. Recommended thresholds:

• 0.999 — tolerates anti-aliasing and subpixel rendering differences
• 0.995 — tolerates minor font/layout shifts across OS versions
• 0.99 — tolerates moderate rendering variation

Per-test threshold

Override the global threshold for a specific test:

[Test]
public Task VerifyImageWithSsimThreshold()
{
    var image = new Image<Rgba32>(11, 11)
    {
        [5, 5] = Rgba32.ParseHex("#0000FF")
    };
    return Verify(image)
        .SsimThreshold(0.95);
}

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Direct SSIM calculation

The SsimComparer class can also be used directly to get the raw SSIM value:

double ssim = SsimComparer.Calculate(receivedStream, verifiedStream);

File Samples

http://file-examples.com/

Icon

Swirl designed by BÖCK, RU from The Noun Project.