Android图像编辑和处理之调整图像明亮度

04 Oct 2013

ColorMatrix是一个4 x 5的矩阵，M' = M * CM
M' = (R', G', B', A') : 为结果颜色矩阵;
M = (R, G, B, A) : 为源颜色矩阵;
CM = (a11 a12 a13 a14 a15)
(a21 a22 a23 a24 a25)
(a31 a32 a33 a34 a35)
(a41 a42 a43 a44 a45) : 为转换矩阵(ColorMatrix);
ColorMatrix的前4列作用于R, G, B, A, 第五列作用与亮度值。
通过ColorMatrix 不仅可以调整亮度还可以调整各个颜色值。

使用ColorMatrix的基本步骤 :

1. 定义一个ColorMatrix : ColorMatrix cm = new ColorMatrix()
2. 设置我们需要的颜色转化矩阵 : cm.set(new float[]{})
3. 给当前Paint设置ColorFilter : paint.setColorFilter(new ColorMatrixColorFilter(cm))
4. 使用设置好的Paint绘图

activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/ChoosePictureButton"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Choose Picture" />

        <SeekBar
            android:id="@+id/brightnessSB"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/ChoosePictureButton"
            android:max="200"
            android:progress="100" />
    </RelativeLayout>

    <ImageView
        android:id="@+id/ChooseImageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <ImageView
        android:id="@+id/AlteredImageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

MainActivity.java:

public class MainActivity extends Activity implements OnClickListener {

	private static final int REQUEST_CODE = 0;

	ImageView chosenImageView;
	ImageView alteredImageView;

	Bitmap alteredBitmap;
	Bitmap bmp;

	Button choosePicture;
	//亮度
	float brightness;

	//调节亮度的进度条
	SeekBar brightnessSB;

	Canvas canvas;
	Paint paint;
	ColorMatrix cm;
	Matrix matrix;

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

		setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

		alteredImageView = (ImageView) findViewById(R.id.AlteredImageView);
		chosenImageView = (ImageView) findViewById(R.id.ChooseImageView);
		choosePicture = (Button) findViewById(R.id.ChoosePictureButton);
		choosePicture.setOnClickListener(this);
		//变换矩阵，可以通过这个矩阵做很多图像缩放、平移和旋转等操作
		matrix = new Matrix();
		//颜色矩阵
		cm = new ColorMatrix();
		//画笔
		paint = new Paint();
		paint.setColorFilter(new ColorMatrixColorFilter(cm));

		brightnessSB = (SeekBar) findViewById(R.id.brightnessSB);
		brightnessSB.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

					@Override
					public void onStopTrackingTouch(SeekBar seekBar) {
					}

					@Override
					public void onStartTrackingTouch(SeekBar seekBar) {
					}

					@Override
					public void onProgressChanged(SeekBar seekBar,
							int progress, boolean fromUser) {

						if (null != bmp) {
							//seekbar的范围为[0, 200]
							//brightness的范围为[-100, 100]
							brightness = (float) (progress - 100);
							cm.set(new float[] { 1, 0, 0, 0, brightness,
									             0, 1, 0, 0, brightness, 
									             0, 0,1, 0, brightness, 
									             0, 0, 0, 1, 0 });

							paint.setColorFilter(new ColorMatrixColorFilter(cm));
							canvas.drawBitmap(bmp, matrix, paint);
							alteredImageView.setImageBitmap(alteredBitmap);
						} else {
							brightnessSB.setProgress(100);
						}
					}
				});
	}

	@Override
	public void onClick(View v) {
		//请求Android的gallery程序，选取sdcard中的照片
		Intent choosePictureIntent = new Intent(Intent.ACTION_PICK,
				MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
		startActivityForResult(choosePictureIntent, REQUEST_CODE);
	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		super.onActivityResult(requestCode, resultCode, data);

		if (requestCode == REQUEST_CODE && resultCode == RESULT_OK) {

			brightnessSB.setProgress(100);
			Uri imageFileUri = data.getData();
			Display currentDisplay = getWindowManager().getDefaultDisplay();
			int dw = currentDisplay.getWidth();
			int dh = currentDisplay.getHeight() / 3 - 100;
			try {
				BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
				bmpFactoryOptions.inJustDecodeBounds = true;
				bmp = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageFileUri), null, bmpFactoryOptions);

				int heightRatio = (int) Math.ceil(bmpFactoryOptions.outHeight
						/ (int) dh);
				int widthRatio = (int) Math.ceil(bmpFactoryOptions.outWidth
						/ (int) dw);

				if (heightRatio > 1 && widthRatio > 1) {
					if (heightRatio > widthRatio) {
						bmpFactoryOptions.inSampleSize = heightRatio;
					} else {
						bmpFactoryOptions.inSampleSize = widthRatio;
					}
				}
				bmpFactoryOptions.inJustDecodeBounds = false;
				bmp = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageFileUri), null, bmpFactoryOptions);

				alteredBitmap = Bitmap.createBitmap(bmp.getWidth(),
						bmp.getHeight(), bmp.getConfig());

				canvas = new Canvas(alteredBitmap);
				canvas.drawBitmap(bmp, matrix, paint);

				alteredImageView.setImageBitmap(alteredBitmap);
				chosenImageView.setImageBitmap(bmp);

			} catch (Exception e) {
				Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
			}
		}
	}
}

git clone https://github.com/lnmcc/brightnessExample.git

ref: 《Android多媒体开发高级编程》