A question about image byte order

ESPHome
1

Hello all,

I recently met a problem and I don't understand it very well. Hope someone can help to explain.

In a few different ESPHome components, they all have this configuration variable: byte_order.

  1. Display>MIPI SPI Display Driver:
    byte_order (Optional): The byte order of the display buffer. Options are big_endian (default) and little_endian. This affects the byte order for the buffer when using 16 bit color depth. The default is appropriate for the majority of displays.

  2. Image:
    byte_order (Optional, string): For RGB565 images, the pixels are converted to 16 bit values. By default these will be stored in little endian byte order (LSB first), but you can override this by setting byte_order to big_endian. Options are little_endian (default) and big_endian. Not applicable to other image formats. Images used in displays and LVGL are expected to be in little endian format.

  3. Online_Image:
    byte_order (Optional, string): For RGB565 images, the pixels are converted to 16 bit values. By default these will be stored in big endian byte order (MSB first), but you can override this by setting byte_order to little_endian. Options are big_endian (default) and little_endian. Not applicable to other image formats.

They are about same thing as I understand, but they have different default value. I am using all these three components in my configuration, and I am also using LVGL.
My question is: shall I unify this byte order in all these components? If yes, which one should I use? big_endian or little_endian?
Thank you in advance!

2

The mipi_spi byte order (or LVGL bye order) relates to the order of bytes stored in the display buffer, which is not necessarily the same as byte order in images.

3

So I keep the byte_order in Mini SPI as default, and define the byte_order in Image and Online_image to little_endian. Is this correct?

4

Just leave it all at the defaults. The online image docs incorrectly state that the default is big endian, it was changed to little endian.