Convert Bitmap grayscale To Alpha - Android Graphics

Android examples for Graphics:Bitmap Scale

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Description

Convert Bitmap grayscale To Alpha

Demo Code


//package com.java2s;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;

import android.graphics.Canvas;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.Paint;

public class Main {
    public static Bitmap grayscale8ToAlpha32(Bitmap grayscaleBitmap) {
        Bitmap grayscaleBitmap32 = convertTo32(grayscaleBitmap);
        return grayscale32ToAlpha32(grayscaleBitmap32);
    }/*from w w w  . j  ava 2 s  .c  o  m*/

    public static Bitmap convertTo32(Bitmap grayscaleBitmap) {
        if (grayscaleBitmap.getConfig() == Config.ARGB_8888)
            return grayscaleBitmap;
        return grayscaleBitmap.copy(Config.ARGB_8888, true);
    }

    public static Bitmap grayscale32ToAlpha32(Bitmap grayscaleBitmap) {
        Bitmap alphaBitmap = Bitmap.createBitmap(
                grayscaleBitmap.getWidth(), grayscaleBitmap.getHeight(),
                Bitmap.Config.ARGB_8888);
        float[] matrix = new float[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                0, 0, 0, 1, 0, 0, 0, 0 };
        Paint grayToAlpha = new Paint();
        grayToAlpha.setColorFilter(new ColorMatrixColorFilter(
                new ColorMatrix(matrix)));
        Canvas alphaCanvas = new Canvas(alphaBitmap);
        alphaCanvas.setDensity(Bitmap.DENSITY_NONE);
        alphaCanvas.drawBitmap(grayscaleBitmap, 0, 0, grayToAlpha);
        return alphaBitmap;
    }
}

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