Question

我希望以编程方式更改背景图像（PNG）的色调。如何在Android上完成？

Answer 1

我测试了接受的答案，遗憾的是它返回了错误的结果。我从here找到并修改了这段代码，效果很好：

// hue-range: [0, 360] -> Default = 0
public static Bitmap hue(Bitmap bitmap, float hue) {
    Bitmap newBitmap = bitmap.copy(bitmap.getConfig(), true);
    final int width = newBitmap.getWidth();
    final int height = newBitmap.getHeight();
    float [] hsv = new float[3];

    for(int y = 0; y < height; y++){
        for(int x = 0; x < width; x++){
            int pixel = newBitmap.getPixel(x,y);
            Color.colorToHSV(pixel,hsv);
            hsv[0] = hue;
            newBitmap.setPixel(x,y,Color.HSVToColor(Color.alpha(pixel),hsv));
        }
    }

    bitmap.recycle();
    bitmap = null;

    return newBitmap;
}

Answer 2

链接的帖子有一些好主意，但用于ColorFilter的矩阵数学可能是（a）复杂的过度杀伤，以及（b）在结果颜色中引入可察觉的变化。

修改janin在此处给出的解决方案 - https://stackoverflow.com/a/6222023/1303595 - 我已将此版本基于Photoshop's 'Color' blend mode。它似乎避免了由PorterDuff.Mode.Multiply引起的图像变暗，并且非常适用于着色不饱和/人工黑色＆amp;白色图像不会造成很大的反差。

/*
 * Going for perceptual intent, rather than strict hue-only change. 
 * This variant based on Photoshop's 'Color' blending mode should look 
 * better for tinting greyscale images and applying an all-over color 
 * without tweaking the contrast (much)
 *     Final color = Target.Hue, Target.Saturation, Source.Luma
 * Drawback is that the back-and-forth color conversion introduces some 
 * error each time.
 */
public void changeHue (Bitmap bitmap, int hue, int width, int height) {
    if (bitmap == null) { return; }
    if ((hue < 0) || (hue > 360)) { return; }

    int size = width * height;
    int[] all_pixels = new int [size];
    int top = 0;
    int left = 0;
    int offset = 0;
    int stride = width;

    bitmap.getPixels (all_pixels, offset, stride, top, left, width, height);

    int pixel = 0;
    int alpha = 0;
    float[] hsv = new float[3];

    for (int i=0; i < size; i++) {
        pixel = all_pixels [i];
        alpha = Color.alpha (pixel);
        Color.colorToHSV (pixel, hsv);

        // You could specify target color including Saturation for
        // more precise results
        hsv [0] = hue;
        hsv [1] = 1.0f;

        all_pixels [i] = Color.HSVToColor (alpha, hsv);
    }

    bitmap.setPixels (all_pixels, offset, stride, top, left, width, height);
}

Answer 3

如果将位图包装在ImageView中，则有一种非常简单的方法：

ImageView circle = new ImageView(this);
circle.setImageBitmap(yourBitmap);
circle.setColorFilter(Color.RED);

我的猜测是，这比单独修改每个像素要快。

Android：如何更改图像的色调？

3 个答案: