Converting image into a "night time" effect (changing pixels colors)

[od11kd]

Hey guys!

So I have to convert an image into a night time view.

Here is what the questions asks:

The night-time effect is created by modifying each pixel’s color based on how different (far) it is from “sky-blue” (Color(58,117,197)). For each pixel, the color distance between the pixel’s color and “sky blue” is computed. Each color channel of the pixel is modified by the ratio of this distance value and 311 (the maximum distance) such that “sky-blue” becomes black (the ratio is 0) and the color most distance from “sky-blue” remains unchanged (ratio is 1).

I have NO clue of what to do or where to start.

Any and all help is greatly appreciated!

Thank you so much in advance!
Oliver.

[KevinWorkman]

I'd have a look at the BufferedImage API to get started.

[JosAH]

For every color (r, g, b) compute the distance w.r.t. (57, 117, 197); let this distance be 'd'. Next computer (r*d/311. g*d/311, b*d/311) (*) and voila.

kind regards,

Jos

(*) 311.5397245938 to be more accurate.