Bug 19515 - SetColorMatrix gives incorrect result
Summary: SetColorMatrix gives incorrect result
Status: NEW
Alias: None
Product: Class Libraries
Classification: Mono
Component: System.Drawing ()
Version: 3.2.x
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2014-05-04 08:42 UTC by Erik Schierboom
Modified: 2014-05-04 08:42 UTC (History)
1 user (show)

Tags:
Is this bug a regression?: ---
Last known good build:


Attachments
The input file for the Gist to test with (24.94 KB, image/jpeg)
2014-05-04 08:42 UTC, Erik Schierboom
Details


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Related Links:
Status:
NEW

Description Erik Schierboom 2014-05-04 08:42:48 UTC
Created attachment 6727 [details]
The input file for the Gist to test with

I believe I have found a bug in the System.Drawing.Imaging namespace. The bug occurs when trying to apply an image transformation using a ColorMatrix instance. After applying the transformation, the resulting image is incorrect. When running the same code on the Microsoft .NET framework, the images turn out correctly.

The code to reproduce this problem can be found below (the input.jpg image has been added as an attachment):


var brightnessFactor = -0.05f;

var image = Image.FromFile("input.jpg");

var colorMatrix = new ColorMatrix(
								new float[][]
											{
												new float[] { 1, 0, 0, 0, 0 }, 
												new float[] { 0, 1, 0, 0, 0 },
												new float[] { 0, 0, 1, 0, 0 },
												new float[] { 0, 0, 0, 1, 0 },
												new float[] { brightnessFactor, brightnessFactor, brightnessFactor, 0, 1 }
										  });


using (var graphics = Graphics.FromImage(image))
{
	using (var imageAttributes = new ImageAttributes())
	{
		imageAttributes.SetColorMatrix(colorMatrix);

		graphics.DrawImage(image, new Rectangle(0, 0, image.Width, image.Height), 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, imageAttributes);

	}
}

// Saving the images results in incorrect images being output on Mono, for any chosen image format
image.Save("output.jpg", ImageFormat.Jpeg);
image.Save("output.png", ImageFormat.Png);
image.Save("output.bmp", ImageFormat.Bmp);

You can also find the code here in a Gist: https://gist.github.com/ErikSchierboom/99cbec38a537d6e65c32

That this code does not execute on Mono is best shown through the following images: 

* The original input.jpg image: http://i.imgur.com/TCY7kl7.jpg
* The output.jpg image when running on the Microsoft .NET Framework: http://i.imgur.com/AFvIHqR.jpg
* The output.jpg image when running on Mono: http://i.imgur.com/czowWrE.jpg

I am running the latest stable release of Mono and 3.4.0 on Unix.