While doing some photography compositing work, I've noticed that if you get any image through Blender's Image node, the final compositing suffers a noticeable degradation in quality. There is really no 3D rendering here whatsoever, it's just the image in pluged to the compositing out. Seems to have something to do with color management. Maybe I am wrong to assume Image node should give a 1:1 result, but I would like to know if there is a fix to this.
Both the before and after are screenshots of the real .png, as size was too heavy to upload. The original picture is a high res png with 16 color depth, but it pretty much happens the same with any image.