Map rainbow colors to RGB

问题

Suppose I have a class RainbowColorsMapper with the constructor RainbowColorsMapper(int n), where n>=2. Now I want to have continuous mapping of rainbow colors from red to violet which I get using the method mapper.getColor(int number) where low values correspond to red end, and high near n to violet end. If n = 2, mapper.getColor(0) returns most left color of the spectrum (near red), and mapper.getColor(1) returns the most right color. Same with bigger n with automatic scaling.

My question: can this be done relatively easy, and if yes what are suggestions on the algorithm?

回答1:

The easiest way to do this will be to work in the HSL colourspace rather than RGB. Create colours where the saturation and lightness are fixed (to 100% and 50%, i would suggest), and the hue varies between suitable endpoints (which you might need to experiment to find). Convert the HSL values to RGB using Color.getHSBColor.

回答2:

Remember that the colours of the rainbow are ordered according to wavelength, so basically in your model, n is somehow related to wavelength. So your question essentially boils down to mapping wavelength (n) to RGB. This is not an entirely trivial process, but for a start, you could check this question out:

Convert light frequency to RGB?

回答3:

Or use a Hue Saturation Value color model, and iterate over Hue.

回答4:

You basically have a hue change from 0 to 300 in the colour model

How to calculate RGB from Hue you can find on Wikipedia

回答5:

its fairly easy once you figure it out. The code underneath will allow you to cycle bewteen all existing rbg colors

  private int r=255;
  private int g=0;
  private int b=0;
  private void nextRGB()
  {
    if ( r == 255 && g < 255 && b == 0 )
      {
      g++;
      }
    if ( g == 255 && r > 0 && b == 0 )
      {
      r--;
      }
    if ( g == 255 && b < 255 && r == 0 )
      {
      b++;
      }
    if ( b == 255 && g > 0 && r == 0 )
      {
      g--;
      }
    if ( b == 255 && r < 255 && g == 0 )
      {
      r++;
      }
    if ( r == 255 && b > 0 && g == 0 )
      {
      b--;
      }
  }
  public Color nextColor()
  {
  nextRGB();
  return makeColor();
  }

  private Color makeColor()
  {
    return new Color(r, g, b);
  }

回答6:

HSL Color allows you to do this easily.

来源：https://stackoverflow.com/questions/5513690/map-rainbow-colors-to-rgb

标签

java

rgb