Ask HN: Why does this image look 3D?

Re:Ask HN: Why does this image look 3D? by apolloartemis on Wednesday April 20, 2022 @04:06PM (#31102264)

I’m just speculating so someone else might know better. What I think is going on is that if your monitor shows especially short-wavelength blues, since this image uses pure #0000FF blue, it’s possible that the blue is so pure and short-wavelength that the lens of your eye doesn’t focus those pixels quite right, and it ends up at a different focal plane than the other colors, especially the pure red which is very long-wavelength.

The iPhone might use less extreme wavelengths for the colors, or use LEDs that are less spectrally-pure.

Edit: like the user named Someone commented below, it looks like this phenomenon has a name - chromostereopsis.

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Re:Ask HN: Why does this image look 3D? by barrystaes on Wednesday April 20, 2022 @05:06PM (#31103002)

I dont think the blue wavelength is it, but a cool fact: humans can only see blue in true focus when under water! This is why you dont want blue text for signage. Backgrounds on traffic signs are ok if the text on it has high contrast and its a reflective material.

Refraction for blue from lens to air is not aligned like red and green are.

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