Develop Reference

Android RGB to YCbCr Conversion and output to imageView

I am doing an image processing which require to convert RGB bitmap image to YCbCr color space. I retrieved RGB value for each pixel and apply the conversion matrix to it.
public void convertRGB (View v) {
if (imageLoaded) {
int width = inputBM.getWidth();
int height = inputBM.getHeight();
int pixel;
int alpha, red, green, blue;
int Y,Cb,Cr;
outputBM = Bitmap.createBitmap(width, height, inputBM.getConfig());
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
pixel = inputBM.getPixel(x, y);
alpha = Color.alpha(pixel);
red = Color.red(pixel);
green = Color.green(pixel);
blue = Color.blue(pixel);
Y = (int) (0.299 * red + 0.587 * green + 0.114 * blue);
Cb = (int) (128-0.169 * red-0.331 * green + 0.500 * blue);
Cr = (int) (128+0.500 * red - 0.419 * green - 0.081 * blue);
int p = (Y << 24) | (Cb << 16) | (Cr<<8);
outputBM.setPixel(x,y,p);
}
}
comImgView.setImageBitmap(outputBM);
}
}
The problem is he output color is different with original. I tried to use BufferedImage but it do not work in Android
Original:
After Conversion:
May I know what is the correct way to handle YCbCr image in android java.

Try setting using below code
ByteArrayOutputStream out = new ByteArrayOutputStream();
YuvImage yuvImage = new YuvImage(your_yuv_data, ImageFormat.NV21, width, height, null);
yuvImage.compressToJpeg(new Rect(0, 0, width, height), 50, out);
byte[] imageBytes = out.toByteArray();
Bitmap image = BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.length);
iv.setImageBitmap(image);
Check documentation for detailed description for YuvImage Class.

Best way to get bitmap pixels array in android?

I am new to Android and need to process a bitmap to extract the pixel information into a multi-dimensional array by collecting only the black pixels i.e. R = 0, G = 0, and B = 0. I noticed that there is a GetPixel(x, y) method which is apparently slow and I need something like this instead. But I'm lost on how to implement a better GetPixel(x, y) method using information from GetPixels(). I am trying something like this currently:
private static int[][] GetPixels(Bitmap bmp)
{
int height = bmp.getHeight();
int width = bmp.getWidth();
int length = width * height;
int[] pixels = new int[length];
bmp.getPixels(pixels, 0, 0, 0, 0, width, height);
int[][]result = new int[width][height];
for(int pixel = 0, x = 0, y = 0; pixel < pixels.length; pixel += 4)
{
int argb = pixels[pixel];//how to access pixel information?
result[x][y] = argb;//store only black pixels??
x++;
if(y == width)
{
x = 0;
y++;
}
}
return result;
}

how to add snow flow effect in android?

I am trying to add snow flow effect. but not succeed
I tried to do the effect of continuously flow the snow.
is it possible? if yes than please give suggestion.
my code is below.
public class MainActivity extends Activity {
private int COLOR_MAX = 0xff;
ImageView image;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
image = (ImageView)findViewById(R.id.imageView1);
Bitmap imagebitmap = BitmapFactory.decodeResource(getResources(),R.drawable.hydrangeas);
applySnowEffect(imagebitmap);
}
Bitmap applySnowEffect(Bitmap source)
{
// get image size
int width = source.getWidth();
int height = source.getHeight();
int[] pixels = new int[width * height];
// get pixel array from source
source.getPixels(pixels, 0, width, 0, 0, width, height);
// random object
Random random = new Random();
int R, G, B, index = 0, thresHold = 50;
// iteration through pixels
for(int y = 0; y < height; ++y) {
for(int x = 0; x < width; ++x) {
// get current index in 2D-matrix
index = y * width + x;
// get color
R = Color.red(pixels[index]);
G = Color.green(pixels[index]);
B = Color.blue(pixels[index]);
// generate threshold
thresHold = random.nextInt(COLOR_MAX );
if(R > thresHold && G > thresHold && B > thresHold) {
pixels[index] = Color.rgb(COLOR_MAX, COLOR_MAX, COLOR_MAX);
}
}
}
// output bitmap
Bitmap bmOut = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
bmOut.setPixels(pixels, 0, width, 0, 0, width, height);
Toast.makeText(getApplicationContext(),"processed",10).show();
return bmOut;
}

I actually read about this the other day. You can use a particle system for Android. A library that can assist with that is found here - https://github.com/plattysoft/Leonids

Well I've just find the solution.
The source is here: code link
The main idea is SnowFallView extends View, and overriding onDraw(Canvas canvas) event, where we drawing our snow flakes drawables.
The code is just tested and works well.

Changing bitmap color/hue efficiently in Android

I am using the following method to change the hue of a bitmap:
public Bitmap changeHue( Bitmap source, double hue ) {
Bitmap result = Bitmap.createBitmap( screenWidth, screenHeight, source.getConfig() );
float[] hsv = new float[3];
for( int x = 0; x < source.getWidth(); x++ ) {
for( int y = 0; y < source.getHeight(); y++ ) {
int c = source.getPixel( x, y );
Color.colorToHSV( c, hsv );
hsv[0] = (float) ((hsv[0] + 360 * hue) % 360);
c = (Color.HSVToColor( hsv ) & 0x00ffffff) | (c & 0xff000000);
result.setPixel( x, y, c );
}
}
return result;
}
It works perfectly and maintains the luminance of the bitmap. However this method is very slow when changing the hue of a bitmap size 800*480 or higher. How can I optimize it without losing too much image quality?

If you wrap your Bitmap in an ImageView there is a very simple way:
ImageView circle = new ImageView(this);
circle.setImageBitmap(yourBitmap);
circle.setColorFilter(Color.RED);

How to reduce the time consuming when i covert a normal image to Sepia colored image?

I used the following code to convert a normal image to Gray-scale and Sepia colored image.
for Sepia Color conversion:
public static Bitmap createSepiaToningEffect(Bitmap src, int depth,
double red, double green, double blue) {
// image size
int width = src.getWidth();
int height = src.getHeight();
// create output bitmap
Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig());
// constant grayscale
final double GS_RED = 0.3;
final double GS_GREEN = 0.59;
final double GS_BLUE = 0.11;
// color information
int A, R, G, B;
int pixel;
// scan through all pixels
for (int x = 0; x < width; ++x) {
for (int y = 0; y < height; ++y) {
// get pixel color
pixel = src.getPixel(x, y);
// get color on each channel
A = Color.alpha(pixel);
R = Color.red(pixel);
G = Color.green(pixel);
B = Color.blue(pixel);
// apply grayscale sample
B = G = R = (int) (GS_RED * R + GS_GREEN * G + GS_BLUE * B);
// apply intensity level for sepid-toning on each channel
R += (depth * red);
if (R > 255) {
R = 255;
}
G += (depth * green);
if (G > 255) {
G = 255;
}
B += (depth * blue);
if (B > 255) {
B = 255;
}
// set new pixel color to output image
bmOut.setPixel(x, y, Color.argb(A, R, G, B));
}
}
// return final image
return bmOut;
}
The above code works fine but the problem is it take more time (more than 60 secs). How can i reduce the time consumption. when i convert the image into Gray-scale it takes less than 2 secs. Can anyone help me to solve this problem.

you can use ndk for it refer to this git repository git://github.com/ruckus/android-image-filter-ndk.git