how to address the issue of distortion (PNG 32BIT with alpha)

miker · ‎2026-01-19

I use the touchGFX to design a UI interface and have a serial issue for the distortion ,the format of picture is PNG with alpha ,color depth is 32 bit ; Even if i set the parameter on the touchGFX designer as RGB565,no either, alpha is true or ARGB888, no either, alpha is true , the real display effect with the 2.8 inch TFT LCD is not so good as following picture that i have no idea to improve this issue,

by the way, the whole frame of LCD window is good to be displaied with R,G,B,white, black;

JohanAstrup · ‎2026-01-20

Hello @miker.

Could you please elaborate on your hardware setup? E.g. which MCU and display interface do you use?
Does the issue also occur when you run the simulator?

Best regards,
Johan

miker · ‎2026-01-20

the hardware setup as follows: STM32L431RCT6 + QSPI FLASH(W25Q128) + SPI interface LCD, the touchGFX designer setup is that RGB565 16BIT and image setting as RGB565 + Dither algorithm (stucki) + Alpha Dither (true);

but the result is that it still have some pixels is distortion for the edge of picture

JohanAstrup · ‎2026-01-23

Did you check how it looks when running in the simulator?

This is a problem for all images, right? And all images are stored in external flash?
If so, could you try placing one image in internal flash to see if that resolves the issue for that specific image?

Best regards,
Johan