标签：setsaturation   图片   android   colormatrix   bitmap   

原图：

效果图：

实现以上效果其实很简单，直接上代码：

public class MainActivity extends Activity {
	private Button btn_start;
	private ImageView img;
	private Bitmap bitmap;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.image_layout);
		initView();
	}

	private void initView() {
		img = (ImageView) findViewById(R.id.iv_image);
		btn_start = (Button) findViewById(R.id.btn_start);
		
		bitmap = ((BitmapDrawable) img.getDrawable()).getBitmap();
		
		btn_start.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				Bitmap bm = ImageTools.toGrayscale(bitmap);
				img.setImageBitmap(bm);
			}
		});

	}
}

/** */
	/**
	 * 图片去色,返回灰度图片
	 * 
	 * @param bmpOriginal
	 *            传入的图片
	 * @return 去色后的图片
	 */
	public static Bitmap toGrayscale(Bitmap bmp) {
		if (bmp != null) {
			int width, height;
			Paint paint = new Paint();
			height = bmp.getHeight();
			width = bmp.getWidth();
			Bitmap bm = Bitmap.createBitmap(width, height,
					Bitmap.Config.RGB_565);
			Canvas c = new Canvas(bm);
			ColorMatrix cm = new ColorMatrix();
			cm.setSaturation(0);
			ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
			paint.setColorFilter(f);
			c.drawBitmap(bmp, 0, 0, paint);
			return bm;
		}else{
			return bmp;
		}
	}

• Set the matrix to affect the saturation of colors. A value of 0 maps the color to gray-scale. 1 is identity.

setSaturation源码是如何实现的：

 public void setSaturation(float sat) {
        reset();
        float[] m = mArray;
        
        final float invSat = 1 - sat;
        final float R = 0.213f * invSat;
        final float G = 0.715f * invSat;
        final float B = 0.072f * invSat;

        m[0] = R + sat; m[1] = G;       m[2] = B;
        m[5] = R;       m[6] = G + sat; m[7] = B;
        m[10] = R;      m[11] = G;      m[12] = B + sat;
    }

一起学android之利用ColorMatrix进行图片的各种特效处理（32）

我们接着看上面的代码，第一步调用了reset方法，我们看下reset方法：

/**
     * Set this colormatrix to identity:
     * [ 1 0 0 0 0   - red vector
     *   0 1 0 0 0   - green vector
     *   0 0 1 0 0   - blue vector
     *   0 0 0 1 0 ] - alpha vector
     */
    public void reset() {
        final float[] a = mArray;
        
        for (int i = 19; i > 0; --i) {
            a[i] = 0;
        }
        a[0] = a[6] = a[12] = a[18] = 1;
    }

接着看就会发现，给图片去色，就是改变颜色矩阵中的值。

将setSaturation中的值设成3看看：

public static Bitmap toGrayscale(Bitmap bmp) {
		if (bmp != null) {
			int width, height;
			Paint paint = new Paint();
			height = bmp.getHeight();
			width = bmp.getWidth();
			Bitmap bm = Bitmap.createBitmap(width, height,
					Bitmap.Config.RGB_565);
			Canvas c = new Canvas(bm);
			ColorMatrix cm = new ColorMatrix();
			cm.setSaturation(3);
			ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
			paint.setColorFilter(f);
			c.drawBitmap(bmp, 0, 0, paint);
			return bm;
		}else{
			return bmp;
		}
	}

通过改变颜色矩阵值，可以实现一些比较好看的效果。

转载请注明出处：http://blog.csdn.net/hai_qing_xu_kong/article/details/45244049 情绪控_

一起学android之给图片去色,返回灰度图片以及ColorMatrix中setSaturation方法的用法（34）

标签：setsaturation   图片   android   colormatrix   bitmap   

原文地址：http://blog.csdn.net/hai_qing_xu_kong/article/details/45244049