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Simple conversion of Tiff file to PNG or JPG generates a strange result, even, at certain times, it is in 3D perspective #2679
Description
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
DEBUGandRELEASEmode - I have searched open and closed issues to ensure it has not already been reported
ImageSharp version
3.1.2
Other ImageSharp packages and versions
No
Environment (Operating system, version and so on)
Linux / Windows
.NET Framework version
.NET 6
Description
I have attached the images that are generating this behavior
Steps to Reproduce
O problema ocorreu em uma imagem específica, segue código mínimo para reprodução:
using (var inImg = File.OpenRead("Image_025.tif"))
using (var outImg = File.Create("Image_025.png"))
using (var imagem = Image.Load(inImg))
{
imagem?.Save(outImg, new PngEncoder());
}
Activity
brianpopow commentedon Mar 6, 2024
The expected decoded image
Image_021.tiffshould look like this:It actually looks like this from the main branch:
The tiffinfo is:
So this is a jpeg compressed tiff image. The image decodes correctly, if we set the ycbcrSubSampling to 1, 1 instead of 2, 2, since this is already handled by the jpeg decoding part.
I am not 100% sure if we always can assume ycbcrSubSampling to 1, 1 with tiff compressed jpeg's. @JimBobSquarePants any thoughts?
JimBobSquarePants commentedon Mar 6, 2024
Does the tag specifically state the subsampling is 2, 2?
https://www.awaresystems.be/imaging/tiff/tifftags/ycbcrsubsampling.html
brianpopow commentedon Mar 7, 2024
Yes YCbCrSubSampling is [2, 2] here in the example image
Image_021.tiffas can be seen in the tiffinfo section above.JimBobSquarePants commentedon Mar 11, 2024
I had another dig through our Tiff code (I really do not enjoy how complicated it is to follow) and it appears to me that our jpeg scan decoder is already handling the deinterleaving so we can treat the subsampling as [1, 1] when using the jpeg decoder.
brianpopow commentedon Mar 11, 2024
Ok, thanks for confirming. I think what makes it so complicated is the myriads of possible combinations of compressions, pixelformats and colorspaces. When ever I think now we finally covered all possible combinations someone comes up with a new tiff variant.
I will try to make a fix for that. @yuridiniz Is it ok, if we use your testimage in a unit-test?
shapeh commentedon Apr 16, 2024
TIFF stands for Thousands of Incompatible File Formats!
Not helpful but couldn't help myself ;)
Always set YcbcrSubSampling to 1:1 for TiffCompression.Jpeg, fixes is…
brianpopow commentedon Aug 24, 2024
Since #2789 was merged, I will close this now as completed
Backport #2679 for v3. See #2994