根据您的评论,您似乎基本上是在尝试将位图的全调色板减少到您指定的 12 个。显然,对于位图中的每个像素,都应该从这 12 个像素中挑选出“最佳匹配”。
我仍然不明白为什么您需要 HSV 值,因为它只是 RGB 组件的不同表示形式 - 它实际上并没有改变问题或其解决方案。
为任何 RGB 颜色找到最佳匹配的简单方法如下所示。
首先构建某种列表,其中包含您要匹配的颜色。我使用了地图,因为您提到您(也)想知道颜色的名称,而不仅仅是 RGB 值。
Map<String, Integer> mColors = new HashMap<String, Integer>();
mColors.put("red", Color.rgb(255, 0, 0));
mColors.put("pink", Color.rgb(255, 192, 203));
mColors.put("voilet", Color.rgb(36, 10, 64));
mColors.put("blue", Color.rgb(0, 0, 255));
mColors.put("green", Color.rgb(0, 255, 0));
mColors.put("yellow", Color.rgb(255, 255, 0));
mColors.put("orange", Color.rgb(255, 104, 31));
mColors.put("white", Color.rgb(255, 255, 255));
mColors.put("black", Color.rgb(0, 0, 0));
mColors.put("gray", Color.rgb(128, 128, 128));
mColors.put("tea", Color.rgb(193, 186, 176));
mColors.put("cream", Color.rgb(255, 253, 208));
然后只需制定一种方法来告诉您最佳匹配。您可以在第二个 for 循环中调用它并将当前像素颜色传递给它。我添加了一些内联注释来解释不同的步骤,但这真的很简单。
private String getBestMatchingColorName(int pixelColor) {
// largest difference is 255 for every colour component
int currentDifference = 3 * 255;
// name of the best matching colour
String closestColorName = null;
// get int values for all three colour components of the pixel
int pixelColorR = Color.red(pixelColor);
int pixelColorG = Color.green(pixelColor);
int pixelColorB = Color.blue(pixelColor);
Iterator<String> colorNameIterator = mColors.keySet().iterator();
// continue iterating if the map contains a next colour and the difference is greater than zero.
// a difference of zero means we've found an exact match, so there's no point in iterating further.
while (colorNameIterator.hasNext() && currentDifference > 0) {
// this colour's name
String currentColorName = colorNameIterator.next();
// this colour's int value
int color = mColors.get(currentColorName);
// get int values for all three colour components of this colour
int colorR = Color.red(color);
int colorG = Color.green(color);
int colorB = Color.blue(color);
// calculate sum of absolute differences that indicates how good this match is
int difference = Math.abs(pixelColorR - colorR) + Math.abs(pixelColorG - colorG) + Math.abs(pixelColorB - colorB);
// a smaller difference means a better match, so keep track of it
if (currentDifference > difference) {
currentDifference = difference;
closestColorName = currentColorName;
}
}
return closestColorName;
}
使用一些预定义的颜色常量进行快速测试的结果:
Color.RED (-65536) -> red (-65536)
Color.GREEN (-16711936) -> green (-16711936)
Color.BLUE (-16776961) -> blue (-16776961)
Color.BLACK (-16777216) -> black (-16777216)
Color.WHITE (-1) -> white (-1)
Color.GRAY (-7829368) -> gray (-8355712)
Color.YELLOW (-256) -> yellow (-256)
Color.MAGENTA (-65281) -> pink (-16181)
括号之间的第一个数字是 Color 常量的实际 int 值,第二个是找到的最佳匹配的 int 值,名称就在它前面。
的结果Color.MAGENTA
也说明了为什么您不应该直接比较颜色的 int 值。实际的 int 值为-65281
,非常接近Color.RED
(-65536) 的值。但是,基于不同组件的最佳匹配是“粉红色”,其值为 -16181。显然,知道颜色被定义为 4 个字节,这完全有道理:
颜色表示为压缩整数,由 4 个字节组成:alpha、red、green、blue。(...) 组件存储如下 (alpha << 24) | (红色 << 16) | (绿色 << 8) | 蓝色的。
来源:android.graphics.Color 参考。
// 编辑:使用 HSV 值似乎也可以正常工作。我确实得到了“洋红色”作为最接近匹配的不同结果——紫罗兰色,而不是粉红色。您可能需要仔细检查值并断点一些东西。例如,我可以想象标准化“H”部分可能会更好。这取决于你...
private String getBestMatchingHsvColor(int pixelColor) {
// largest difference is 360(H), 1(S), 1(V)
float currentDifference = 360 + 1 + 1;
// name of the best matching colour
String closestColorName = null;
// get HSV values for the pixel's colour
float[] pixelColorHsv = new float[3];
Color.colorToHSV(pixelColor, pixelColorHsv);
Iterator<String> colorNameIterator = mColors.keySet().iterator();
// continue iterating if the map contains a next colour and the difference is greater than zero.
// a difference of zero means we've found an exact match, so there's not point in iterating further.
while (colorNameIterator.hasNext() && currentDifference > 0) {
// this colour's name
String currentColorName = colorNameIterator.next();
// this colour's int value
int color = mColors.get(currentColorName);
// get HSV values for this colour
float[] colorHsv = new float[3];
Color.colorToHSV(color, colorHsv);
// calculate sum of absolute differences that indicates how good this match is
float difference = Math.abs(pixelColorHsv[0] - colorHsv[0]) + Math.abs(pixelColorHsv[1] - colorHsv[1]) + Math.abs(pixelColorHsv[2] - colorHsv[2]);
// a smaller difference means a better match, so store it
if (currentDifference > difference) {
currentDifference = difference;
closestColorName = currentColorName;
}
}
return closestColorName;
}