ImageSharp sometimes add gray rectangle at the bottom right

[laitauchocolat]

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

3.1.0

Other ImageSharp packages and versions

3.0.1

Environment (Operating system, version and so on)

Windows 11

.NET Framework version

.NET 6

Description

On some picture, ImageSharp will add a gray rectangle at the bottom right,
Original:
Final:

Steps to Reproduce

Download sample projet c#
Replace fb.jpg with the original picture:

try it with version 3.0.1, (no gray square)
erease debug + obj and install the latest version 3.1.2 and execute, (gray square)

Images

No response

[JimBobSquarePants]

@br3aker would it be possible for you to have a look at this? I thought we’d fixed it previously.

[omuleanu]

I got the same thing net8.0

I save it like this:

using var fstream = file.OpenReadStream(); // file is IFormFile (asp.net core)

var img = Image.Load(fstream);
await img.SaveAsync(filePath, new JpegEncoder { Quality = 50 });

cropping the bottom part helps avoid the problem

[JimBobSquarePants]

Does the issue happen on decode or encode?

I got the same thing net8.0

What do you mean by this? Same version different target framework?

[omuleanu]

@JimBobSquarePants
version 3.1.2
net8.0
the image with the gray square is the result of img.SaveAsync(filePath, new JpegEncoder { Quality = 50 });
I assume this is encode.

[JimBobSquarePants]

OK. Can you please encode the image as Png and let me know whether the result is the same?

[omuleanu]

using await img.SaveAsPngAsync(Path.ChangeExtension(filePath, "png")); I also get the gray square,
I'm also doing a clone and resize to 300x300 and that one also has the square.

[JimBobSquarePants]

Decoder then. Will need to figure out the commit that broke it.

[br3aker]

Hm, that's strange. I'll take a look this weekend.

[JimBobSquarePants]

Thanks @br3aker it was likely something around this. https://github.com/SixLabors/ImageSharp/pull/2516/files#diff-2ffe67fdac3f8753169905e125b8ddb27ec966025580e775f7b07e4c6f2c8d0dR215

[br3aker]

Thanks @br3aker it was likely something around this. #2516 (files)

That's actually it but fix is rather complex if we don't want to break existing logic with that fast 'DOS images'. Working on it atm.

[JimBobSquarePants]

@br3aker I kid you not I was JUST this second writing a comment to see if you wanted me to have a look. 🤪

Thanks for helping out. Much appreciated!

[phoebusryan]

This also happens in Version 2.1.6. It's not an Version 3-Issue

[hightechie]

This also happens in Version 2.1.6. It's not an Version 3-Issue

I upgraded from 2.1.3 to 2.1.7 due to CVE-2024-27929 and am seeing the gray rectangle on certain images also.

[JimBobSquarePants]

The same code is in both v2 and v3. Trust @br3aker in his analysis, he knows more about that decoder than anyone on the planet.