There are the CSF curves:
blog.kasson.com
I just posted this link in another response, but it may be useful in discussing color sharpness:
blog.kasson.com
Not entirely, apparently.
Less sensitive, yes - but not as much as once assumed.
No, but there isn't always a significant luma contrast in coloured patterns.
That's why a painting can combine lines drawn with a pen (giving a sharp luminance signal) with quite loose washes of watercolour. This technique is widely used in illustrations to children's books, from Beatrix Potter's "Peter Rabbit" series onward.
It's also why PhotoCD and many video encodings of color work and worked.
I don't have any experience with Foveon images, but I have a lot of experience with Betterlight images, which also capture all three raw color planes at the same location. I think the reason the Betterlight 144MP backs punch so far above their weight is the relative lack of aliasing wrt Bayer-CFA images, not sharpness.
It depends what you mean by "sharp". Clearly, outlining an edge will sharpen it.
Here's a visual demo of how the eye responds to chroma changes at varying spatial frequency.
The rules of European heraldry specify which colors or 'tinctures' in arms can be directly adjacent and which ones need a dividing line between them. The tinctures are divided into colours, which are dark, and metals which are light. No colour can be placed next to another colour, and no metal next to another metal without a dividing line. But it is OK to place metals and colours adjacent. While the history of this "rule of tincture" is unclear, it seems to have been observed from the beginning, and certainly it makes the patterns more visible.
Thank you for that!
I can see how it works with a sine-wave grating.
And yet it seems to work fine in art deco posters...
It can. but there are interesting aspects that you might not know about pixel shift. The need for multiple images isn't ideal for moving subjects and scenes in which there's movement. Based on multiple sources of information, Pixel Shift is more of a way to decrease the level of noise rather than increase resolution. Interestingly, after posting a question about whether or not the lens needs to be able to resolve more with pixel shift rather than without it, I seen various responses. Not everyone agreed that the lens needs to be better, so basically, that's a question that I've been having but hasn't been adequately answered for me. It's also possible to get more resolution by making a large image from multiple smaller ones, which might possibly be better, but that's different.
Thank you for your response. I am aware that motion artifacts reduce the applicability of pixel-shift, though some cameras started adding in-camera motion artifact removal. Unfortunately, that feature comes with a reduction in resolution and other related benefits.
You cannot separate false colors from (lack of) resolution in general.
Of course the better the lens the better the 'sharpness' in both shifted and unshifted captures because - taking the Modulation Transfer Function as input to the sharpness metric of choice - imaging system MTF is the product of the individual component MTFs, which can be simplified for this discussion as follows:
Most of the adjacent colors in that poster differ greatly either in value or saturation, and that generally is OK according to design rules. But notice that the "Bermuda" text and the woman's hat—similar in value and saturation with the surrounding sky—are both outlined in white, as the old design rules would require.
