Sure, it wouldn’t be black. If it was a pure red (absolutely no other colours, just pure 100% red) then it wouldn’t have a colour to a dog. It would have a shade, and it certainly wouldn’t be absolutely pitch black but close enough. If, however, it’s not a pure red then it would appear yellow or blue as in the picture you posted.
No, because the dog would know that if someone says “red” they probably mean “black” or some shade of black, and “green” would mean “white” or some shade of white.
That doesn’t make sense. They don’t interpret the hue as we do, but they still see different brightness, red wouldn’t be just black.
Here’s a dog vision simulation
Sure, it wouldn’t be black. If it was a pure red (absolutely no other colours, just pure 100% red) then it wouldn’t have a colour to a dog. It would have a shade, and it certainly wouldn’t be absolutely pitch black but close enough. If, however, it’s not a pure red then it would appear yellow or blue as in the picture you posted.
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No, because the dog would know that if someone says “red” they probably mean “black” or some shade of black, and “green” would mean “white” or some shade of white.