TextureMapper bilinear interpolation issue for RGB565

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Hi all,

We use TextureMapper bilinear interpolation to rotate the image, but in RGB565 mode, dirty spots will appear on the border of the image.

This problem will appear in version 4.15, but not in 4.12.3.

Any suggestion to avoid the issue?

TouchGFX

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JasonNiBest answer

Associate

Hi Romain,

We found that TouchGFX v4.16.0 and changelog showed that this bug has been fixed.

We confirm that the issue in this version has been resolved.

V4.16.0 Changelog

Bugfixes in TouchGFX Core:

Fixed the border of images drawn in bilinear mode by the texture mapper.

Thanks for your help.

Best Regards,

Jason

Romain DIELEMAN

ST Employee

Hi,

This is interesting. Could you share your image so that I can try to replicate this ?

Are you able to see those dirty spots when running on target ?

/Romain

JasonNiAuthor

Associate

Hi,

Attached is the image of sample.

We can see those dirty spots on the target.

At first we found it on the target side, and then we tried to see if the problem could be reproduced from the simulator.

After seeing this problem in the simulator, I guess it might be caused by the Biliner algorithm.

/Jason

Romain DIELEMAN

ST Employee

Hi,

I believe I was able to replicate it. As you said it seems to be linked to the rendering algorithm. The "nearest-neighbor" algorithm just makes the animation worse when rotating. Would using another image be ok for your project ? Instead of using a narrowing hand, a rectangular one could potentially prevent this issue.

What board are you using by the way ?

/Romain

JasonNiAuthor

Associate

Hi,

I tried another image and I have the same problem. I have modified the image size to be square, but there will still be noise on the border.

Our workaround is to use the "Nearest-neighbor" algorithm, but the image quality may not be fine. I hope you can help report this issue and see if the next version can resolve this issue.

Our custom board uses the STM32F746.

/Jason