HamX Old Blender Image Format

I have learned about a new Blender image format from old Blender Versions called HamX. Apparently, it’s described as “Blender’s own self-developed 8 bits RLE (Run Length Encoded bitmap) format; it creates extremely compact files that can be displayed quickly. To be used only for previsualization of animations.” I am not sure how to save or view HamX images. Does anyone know how to deal with these HamX images? Thanks!
image

Current blender versions use openexr, https://www.openexr.com/
I guess its compatible and you could use an exr-viewer.