I'm colour blind, and if a picture is in black and white, I can't always tell.
A long while back our CRT TV broke, and started displaying everything without colour - I had no idea until my wife pointed it out! It's like my mind just makes up what it doesn't see.
Another example that I always use is grass: if you showed me a cropped image of grass and I didn't know it was grass, I'll tell you "I don't know what colour it is, but I think it's either red, brown or green". But if you point to some grass, I'll always say "it's green!".
We had a bunch of different candies on the table at game night and I gave my friend some M&Ms, he thought they came from a bag of mint flavored M&Ms. He said, "wow I never tried these before, they really taste like mint." We all did a double take, he definitely did not eat mint M&Ms, I don't really remember if we even had mint M&Ms at the table. I believe him when he says he says he tasted mint though, like his brain placeboed the mint into place.
With the grass example, I'm actually not entirely sure! I mean, I obviously know that green is the correct answer, but that knowledge kind of makes me feel like I'm seeing green.
But colour blindness is kind of weird, because for any given thing/colour it's never just "I don't know" - I can narrow it down to a few options, and usually one of them is the correct one; like for a desaturated green, I might think it's grey, green or pink.
I love this description http://www.dspguide.com/InnerLightTheory/frontcov.htm of the front cover of a free ebook on consciousness (there's a link to the book at the bottom of the page. the author isn't a neuroscientist or a philosopher but an electrical engineer, but his theory of consciousness is interesting nonetheless. he also has a free ebook on signal processing http://www.dspguide.com and it's pretty cool). The main theme of the book is that consciousness arises exactly because we don't have a "raw feed" and we can't inspect our inner workings; a being that can will not have the same subjective experience.
> The front cover illustrates the image detected by your right eye as you stand a few feet from the Mona Lisa. The gray filaments are regions where you are totally blind, a result of blood vessels in the retina blocking the detection of light. Likewise, the large rectangular region is where the optic nerve connects with the retina, where humans are also sightless. This is called the blind spot, and is really quite large, about the size of an apple at arm’s length. As long as your eye remains fixed on the center of the painting, these gray regions are totally blocked from your gaze; you perceive nothing about the image in these areas.
> When you first looked at the cover, you probably wondered what the gray spider-like pattern represented. It probably struck you as quite odd, like something out of a bad science fiction movie. It was totally unfamiliar and foreign to your conscious experience. But how could this possibly be? This pattern has been superimposed on your visual field since you first opened your eyes as an infant. Even as you read this paragraph the pattern is present. It should be more familiar to you than anything you have ever seen. How is it possible that our conscious experience knows nothing of these blind areas?
Looking forward to HDR and Image Stablization in Humanity 2.0 coming in 102022.
I read about an experiment where people were shown various black and white drawings over random grayish backgrounds. They then had to estimate the hue of the grayish background - which was tricking because it only has slight amount of red, or blue, etc). The results clearly shows that the black sketch which was overlayed on the gray background skewered peoples perceptions of the color of the background. People could not simply observe the color of the background without their other knowledge skewing their perception.
Yet another example that we don't really get a "raw feed" from out senses. What we perceive has already gone through a lot of "post-processing" by our brain.