java - 根据图像修改背景颜色(主题)

Question

我正在尝试找到最适合加载图像的颜色并将其应用到背景中。适应图像并使 UI 感觉更自然。 到目前为止我已经找到了 2 个方案:

1> 平均像素(下面的代码):

final Color acclimatizeAverage(BufferedImage img) {
        long avgr = 0, avgb = 0, avgg = 0;
        for (int i = 0; i < img.getWidth(); i++) {
            for (int j = 0; j < img.getHeight(); j++) {
               Color c = new Color(img.getRGB(i, j));
               avgr += c.getRed(); avgb += c.getBlue(); avgg += c.getGreen();
            }
        }
        avgr = (avgr/(img.getHeight()*img.getWidth()));
        avgg = (avgg/(img.getHeight()*img.getWidth()));
        avgb = (avgb/(img.getHeight()*img.getWidth()));
        Color c = new Color((int)avgr, (int)avgg, (int)avgb);
        return c;
    }

2> 将像素分组到固定的颜色箱中(下面的代码):

 Map<Color, Integer> createBins() {
        Map<Color, Integer> bins = new HashMap<>();
        bins.put(Color.red, 0);
        bins.put(Color.magenta, 0);
        bins.put(Color.orange, 0);
        bins.put(Color.PINK, 0);
        bins.put(Color.yellow, 0);
        bins.put(Color.LIGHT_GRAY, 0);
        bins.put(Color.GREEN, 0);
        bins.put(Color.GRAY, 0);
        bins.put(Color.DARK_GRAY, 0);
        bins.put(Color.CYAN, 0);
        bins.put(Color.BLUE, 0);
        bins.put(Color.BLACK, 0);
        return bins;
    }

    int compare(Color a, Color b) {
        return (int)Math.sqrt((a.getRed() - b.getRed())*(a.getRed() - b.getRed()) 
                + (a.getBlue() - b.getBlue())*(a.getBlue() - b.getBlue()) 
                + (a.getGreen()- b.getGreen())*(a.getGreen()- b.getGreen()));
    }

    BufferedImage acclimatizeGrouping(BufferedImage img) {
        Map<Color, Integer> bins = createBins();
        for (int i = 0; i < img.getWidth(); i++) {
            int min = Integer.MAX_VALUE; Color minC = null;
            for (int j = 0; j < img.getHeight(); j++) {
               Color c = new Color(img.getRGB(i, j));
                for (Map.Entry<Color, Integer> entry : bins.entrySet()) {
                    Integer integer = compare(entry.getKey(), c);
                    if(integer < min) {
                        min = integer;
                        minC = entry.getKey();
                    }
                }
                bins.put(minC, bins.get(minC)+1);
            }
        }
        int max = -1, n = 1; Color c = null;
        for (Map.Entry<Color, Integer> entry : bins.entrySet()) {
            Integer integer = entry.getValue();
            if(integer > max) {
                max = integer;
                c = entry.getKey();
            }
        }
        return c;
    }

但是分组产生了奇怪的结果......
左侧是分组后产生的颜色，右侧是图像
为什么会产生这样的结果？？？

平均会产生更正确的结果:

Answer 1

我认为问题在于 RGB 不是人类欧几里得空间。您使用欧氏距离来比较颜色，但这对人类的色感不利。请参阅this link了解更多信息。

编辑:更精确，您应该使用此算法:

typedef struct {
   unsigned char r, g, b;
} RGB;

double ColourDistance(RGB e1, RGB e2)
{
  long rmean = ( (long)e1.r + (long)e2.r ) / 2;
  long r = (long)e1.r - (long)e2.r;
  long g = (long)e1.g - (long)e2.g;
  long b = (long)e1.b - (long)e2.b;
  return sqrt((((512+rmean)*r*r)>>8) + 4*g*g + (((767-rmean)*b*b)>>8));
}