Android ColorMatrixColorFilter example: Creates a 'ghost' bitmap version of the given source drawable (ideally a BitmapDrawable). In the ghost bitmap, the RGB values take on the values from the 'color' argument, while the alpha values are derived from the source's grayscaled RGB values. The effect is that you can see through darker parts of the …

AndroidCreateGhostIcon.java

/**
 * Creates a 'ghost' bitmap version of the given source drawable (ideally a BitmapDrawable).
 * In the ghost bitmap, the RGB values take on the values from the 'color' argument, while
 * the alpha values are derived from the source's grayscaled RGB values. The effect is that
 * you can see through darker parts of the source bitmap, while lighter parts show up as
 * the given color. The 'invert' argument inverts the computation of alpha values, and looks
 * best when the given color is a dark.
 */
private Bitmap createGhostIcon(Drawable src, int color, boolean invert) {
    int width = src.getIntrinsicWidth();
    int height = src.getIntrinsicHeight();
    if (width <= 0 || height <= 0) {
        throw new UnsupportedOperationException("Source drawable needs an intrinsic size.");
    }

    Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    Paint colorToAlphaPaint = new Paint();
    int invMul = invert ? -1 : 1;
    colorToAlphaPaint.setColorFilter(new ColorMatrixColorFilter(new ColorMatrix(new float[]{
            0, 0, 0, 0, Color.red(color),
            0, 0, 0, 0, Color.green(color),
            0, 0, 0, 0, Color.blue(color),
            invMul * 0.213f, invMul * 0.715f, invMul * 0.072f, 0, invert ? 255 : 0,
    })));
    canvas.saveLayer(0, 0, width, height, colorToAlphaPaint, Canvas.ALL_SAVE_FLAG);
    canvas.drawColor(invert ? Color.WHITE : Color.BLACK);
    src.setBounds(0, 0, width, height);
    src.draw(canvas);
    canvas.restore();
    return bitmap;
}