0
$\begingroup$

Wen pairing two or more colors together, some "clash" or cause a effect visually where the two colors meet. To me it appears to be a black line between the colors or shading when in fact there is not. I grey scaled the picture to confirm. In dogs, they would just see different shades of grey and this effect would not affect them. So, what is this that which make this effect in the brain?

enter image description here

enter image description here

Improve this question
$\endgroup$
4
  • $\begingroup$ Could you explain what you mean by "clash"? I don't see any real difference between the colored image and the grayscale one. Maybe it's something specific to YOUR brain - or maybe I'm the odd one :-) $\endgroup$
    – jamesqf
    Jul 10, 2021 at 16:41
  • 1
    $\begingroup$ @jamesqf there is an optical illusion of a very thin black line between the red and the blue sections in the top image. There is less contrast between the two gray tones in the bottom image, so this illusion doesn't appear as evident (at least to me). Do you know if you have some version of color blindness? $\endgroup$
    – MattDMo
    Jul 10, 2021 at 19:51
  • 1
    $\begingroup$ @MattDMo: No, I don't have color blindness, and I see that "illusion" on the gray scale image as well, though not as strongly. If it is an illusion, and not an artifact of whatever created the image, But I haven't tried blowing up either image myself. I would suspect, from having done some work with computer feature recognition, that it's an artifact of higher processing levels segmenting the image into recognicable features, but I don't actually know. $\endgroup$
    – jamesqf
    Jul 11, 2021 at 16:17
  • $\begingroup$ @jamesqf it is indeed an artifact i.stack.imgur.com/3E7PO.png $\endgroup$
    – rotaredom
    Jul 13, 2021 at 14:37

1 Answer 1

Reset to default
1
$\begingroup$

Magnify your image.

I just put it in GIMP and it is clear that there are several pixels in the red and the blue near the border which are a darker color than those adjacent - the drawing program must be responsible.

Lateral geniculate nucleus

That said, differences of red and green hue are handled more in the parvocellular layers of the LGN, while grayscale differences are handled more in the magnocellular layers, with blue cones contributing to the koniocellular layers the most. In your images, all three are involved. There are some individual differences reported between these regions and their timing of activation in regard to dyslexia - it's a hot topic, and these variations seem to be the explanation for that perplexing condition. I'm not going to point to any specific paper because I'm not sure how to interpret the "clashing", but there's some interesting reading there!

Improve this answer
$\endgroup$
5
  • $\begingroup$ Your first paragraph about magnification is not, I think, relevant. What you are observing is something called “anti-aliasing, which is a way in which a smooth, rather than a jagged, border is produced (in the brain). The visual effects need not be generated by computer — they were and are a staple of certain printed publications for centuries. $\endgroup$
    – David
    Jul 11, 2021 at 18:35
  • $\begingroup$ @David: I can't say that I've ever noticed them in print images, but are you sure the ones you see aren't an artifact of the inks mixing at the border? $\endgroup$
    – jamesqf
    Jul 12, 2021 at 6:36
  • $\begingroup$ Actually my comment is not quite right. In high quality printed images a smooth interface between two inks of different colours occurs because the individual dots of ink are so small. On a computer screen there is a limit (traditionally 72 dots per inch, now generally 120 dpi or higher, but still enough to give a visible jagged edge between two adjacent colours. This is called aliasing. Computer programs can trick the eye into seeing a smooth edge by making a transition between the colours of the pixels at the interface — anti-aliasing. cont. $\endgroup$
    – David
    Jul 12, 2021 at 7:14
  • $\begingroup$ cont. Looking closely at the example and generating one of my own in Photoshop with the same colours I notice that the anti-aliasing in the example is different from that produced automatically by Photoshop in having darker colours at the interface. As you say, it must have been produced by the program that generated the image, although quite why I am not sure. Perhaps a compression effect. Highly compressed jpegs can do this, although the image is currently in png format. I could add a composite illustration to your answer if you don't object. $\endgroup$
    – David
    Jul 12, 2021 at 7:20
  • $\begingroup$ cont. Got it wrong again. It's not a jpeg compression artifact, which is different, but a sharpening artifact. It's the way that Photoshop's "unsharp mask" filter produces its effect. I can reproduce its generation in a series of images. So as far as I can see the question is concerned, the poster is seeing what is actually there, so it is not an optical illusion. The general area of how these image manipulations trick the brain is interesting enough, but not particularly new or subject to detailed biological analysis. They just know how to do it. $\endgroup$
    – David
    Jul 12, 2021 at 8:17

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .