JPEG Gui icon without Touch GFX on stm32h7

[MMARI.1]

hi,

I am currently using BMP + rgb565 LTDC display for GUI icon creation without Touch GFX ( Everything is on "" C"" only and Manual preparation icon using hex converter ).

Already known one is ! for a small size ,BMP is OK but large size BMP icon  will increase the size and processing time  .

   

Above Picture size is 6.30KB in BMP                                                

Above Picture size is 2.03KB in JPEG      

Visually i could not see any difference  BMP and JPEG in my laptop   .

Now i am using internal memory for small icon  (Now working with stm32h723zgt6 and plan to upgrade to stm32u5 series )

Please clarify my doubts. 

0. Can i use Hardware Inbuilt JPEG decoder for JPEG  GUI icon creation with rgb565 format  ? . 

1. Do you think i can achieve best frame rate by  Hardware Inbuilt JPEG decoder ?.

2. Either i will get same picture quality like BMP in Hardware Inbuilt JPEG decoder ?

[Osman SOYKURT]

Hello @MMARI.1 ,

As far as I know, not the entire STM32U5 series has the JPEG codec, but only on STM32U5Fx/5Gx devices (check AN5766 - section 3.16).

0- Yes you can use the JPEG codec but the decoder does not output directly in RGB565 format; you will need to implement an additional conversion step to obtain RGB565 data.

1- I don't think the the YCbCr to RGB conversion is hardware accelerated and therefore must be performed by the software. This has to be considered if you want to achieve a high framerate.

2- I expect the quality to be more or less similar for small images (the color palette is also smaller), but it's definitely lower quality than BMP if you have big images and lot of colors (like if your image uses gradients)

[Osman SOYKURT]

Hello @MMARI.1 ,

Do you need any further help on this topic? 

[unsigned_char_array]

Is the image static(compiled) or dynamic (loaded from external interface, such as SD-card)?
If so you can use other compression methods. In software or in hardware.

BMP can be saved in 565-format using gimp:

3338 bytes

3338 bytes

[MMARI.1]

hi,

https://github.com/STMicroelectronics/STM32CubeU5/blob/main/Projects/STM32U5G9J-DK2/Examples/JPEG/JPEG_DecodingFromFLASH_DMA/Src/main.c 

from the above example my understanding is i can bring directly data from internal flash to display(LTDC) by using JPEG decoder . Please share your technical ideas me further