- cover_image: 960x432
- cover_image_mobile: 110x50
- cover_color: Principal color of the image. There are online tools like http://mkweb.bcgsc.ca/color-summarizer/?analyze and https://png-pixel.com/
To crop the images, it's easy to do it with Gimp.
- Image -> Scale image (only the width, keeping the height proportion)
- Image -> Crop to content (Select a rectangle and ajust position and size pixels with panel)
- File -> Export as
- Compress image with online tools: https://compressjpeg.com/es/ https://compresspng.com/
- @todo automatize this process.