This is a really interesting question, and one I looked into (though not very thoroughly) when I was putting together my Day/Night module demo. (I found it difficult. The basic Photoshop filters I experimented with did not give particularly good effects.)
If you think of it from a physics POV, the color of something is determined by the light that hits it as well as its particular absorption and reflection characteristics. I would guess that you can probably approximate that pretty well by just multiplying the color of the light with the "color" of the object, perhaps after suitable calibration.
So as a first approximation, I would use a multiply formula, using a shifting light color. Since our eyes tend to compensate for light intensity, I wouldn't vary the brightness all that much. I might also treat the sky separately, perhaps designing a few color ramps manually and interpolating between them. (If you want an example, Cryo's Dune has beautiful day-night fades.) The color of the light is mainly determined by the color of the sky, so you could even derive the color to use for the palette multiplication from the average hue of the sky.
Secondly, you might want to incorporate the Purkinje effect: in dim light we perceive blue more clearly than other colors, so e.g. reds will appear to darken more. I think this will go a long way to give it that spooky night-time look.
BTW, apparently sunrise and sunset look pretty much identical, subject to atmospheric conditions. The perceived difference is psychological more than actual.
If you think of it from a physics POV, the color of something is determined by the light that hits it as well as its particular absorption and reflection characteristics. I would guess that you can probably approximate that pretty well by just multiplying the color of the light with the "color" of the object, perhaps after suitable calibration.
So as a first approximation, I would use a multiply formula, using a shifting light color. Since our eyes tend to compensate for light intensity, I wouldn't vary the brightness all that much. I might also treat the sky separately, perhaps designing a few color ramps manually and interpolating between them. (If you want an example, Cryo's Dune has beautiful day-night fades.) The color of the light is mainly determined by the color of the sky, so you could even derive the color to use for the palette multiplication from the average hue of the sky.
Secondly, you might want to incorporate the Purkinje effect: in dim light we perceive blue more clearly than other colors, so e.g. reds will appear to darken more. I think this will go a long way to give it that spooky night-time look.
BTW, apparently sunrise and sunset look pretty much identical, subject to atmospheric conditions. The perceived difference is psychological more than actual.
