Image format for display on Waveshare epaper

Hi all,
I’ve started working with 2.9" waveshare epaper using esphome. It works just great.

I’m trying to add images and they are displayed as a black box. I tried using images from some of the examples here on the forums, and they display correct, so it is probably an image format issue. I’m using a png file, using only two colors. I’m attaching an example.

Any idea what format should the images be, and how to convert them?


Well, found the answer. Don’t use transparent png file.