All 16,777,216 RGB colors in one image with no repeat pixels

[۩]

From here: Images with all colors

 

[obliguhl]

even better

 

[Ufostrahlen]

"All 16,777,216 RGB colors in one image with no repeat pixels". Should apply for this white rectangular as well: ◼

(okay, it's a unicode character, not an image - just imagine I've posted a white 1x1 px image.)

 

[steppa]

And all CMYK colors in one book.