I always thought it was related to my (deuteranopia) colour blindness too, but actually I managed to see these ones using the technique they describe, bringing

I always thought it was related to my (deuteranopia) colour blindness too, but actually I managed to see these ones using the technique they describe, bringing the images close to my face until they overlap, then move them further away). I've never had any of these work for me in the past, but this one has made it click and I can now see others.