在安卓系统中使用colorMatrix让黑屏变暗

Question

我目前有下面的代码来获得一个Bitmap对象，去掉颜色，然后把它变成红色，这是可行的，但我需要图像中较暗的元素来看起来更暗，目前就像有人在图像上放了一层红色的胶片，这几乎就是我想要的，但需要黑色更暗：

Bitmap sourceBitmap = BitmapFactory.decodeFile(imgPath);
        float[] colorTransform = {
                0, 1f, 0, 0, 0, 
                0, 0, 0f, 0, 0,
                0, 0, 0, 0f, 0, 
                0, 0, 0, 1f, 0};
        ColorMatrix colorMatrix = new ColorMatrix();
        colorMatrix.setSaturation(0f); //Remove Colour 
        colorMatrix.set(colorTransform); //Apply the Red

        ColorMatrixColorFilter colorFilter = new ColorMatrixColorFilter(colorMatrix);
        Paint paint = new Paint();
        paint.setColorFilter(colorFilter);   

        Display display = getWindowManager().getDefaultDisplay(); 

        Bitmap resultBitmap = Bitmap.createBitmap(sourceBitmap, 0, (int)(display.getHeight() * 0.15), display.getWidth(), (int)(display.getHeight() * 0.75));            

        image.setImageBitmap(resultBitmap);

        Canvas canvas = new Canvas(resultBitmap);
        canvas.drawBitmap(resultBitmap, 0, 0, paint);

Answer 1

c = 2;//this will boost your contrast by 2x thus deepening the black (and lightning the white). I'm not sure why at 0 you have anything but black... maybe I don't understand the matrix as well as I think I do... I thought 1 (in place of my c) gets you the original colors.

Anyway... give that a whirl. 


float[] colorTransform = {
                c, 1f, 0, 0, 0, 
                0, c, 0f, 0, 0,
                0, 0, c, 0f, 0, 
                0, 0, 0, 1f, 0};

Answer 2

颜色矩阵中前三行的最后一列改变图像的亮度。它在-255...255之间变化。-255将为您提供黑色图像，255将使其为白色。这种方法可以改变你的对比度。比明亮的物体会变得更深，更暗，更暗。然后你可以将你的亮度设置为重复的位置。对比度在-1...1之间更改。

private static void setContrast(ColorMatrix cm, float contrast) {
                float scale = contrast + 1.f;
                   float translate = (-.5f * scale + .5f) * 255.f;
                cm.set(new float[] {
                       scale, 0, 0, 0, translate,
                       0, scale, 0, 0, translate,
                       0, 0, scale, 0, translate,
                       0, 0, 0, 1, 0 });
        }