Develop Reference

How to increase pixels size of a Bitmap

I want to know if it's possible to modify bitmap pixels by pixels. I'm not asking for changing bitmap size/scale. What I'm looking for is that I want to increase size of all or some specific pixels of a bitmap.
I tried this
Thread(Runnable {
val newBitmap = Bitmap.createScaledBitmap(bitmap, bitmap.width * 4,
bitmap.height * 4, true);
for (x in 0 until bitmap.getWidth()) {
for (y in 0 until bitmap.getHeight()) {
val pixel = bitmap.getPixel(x, y);
val redValue = Color.red(pixel)
val blueValue = Color.blue(pixel)
val greenValue = Color.green(pixel)
newBitmap.setPixel(x * 4, y * 4, Color.rgb(redValue, greenValue, blueValue))
}
}
runOnUiThread({ imageView.setImageBitmap(newBitmap) })
}).start()
But it has no effect on the bitmap. Any kind of help is highly appreciated.

If you want to pixelate just a part of your bitmap, then you could create a Bitmap of the part which you wish to edit, perform changes on the new bitmap and then overlay the changed bitmap on top of the original bitmap.
So for example, you could pixelate a portion of a Bitmap by doing something along the following lines,
#Override
protected void onCreate(Bundle savedInstanceState) {
...
Bitmap originalBitmap = ((BitmapDrawable) getResources().getDrawable(R.drawable.drawabledroid)).getBitmap();
// Pixelate just the top half
int x = 0, y = 0, width = originalBitmap.getWidth(), height = originalBitmap.getHeight()/2;
//Or pixelate a rectangle in the middle
//int x = originalBitmap.getWidth()/2 - 50, y = originalBitmap.getHeight()/2 - 50, width = 100, height = 100;
//Get bitmap with region you want to pixelate
Bitmap original = Bitmap.createBitmap(originalBitmap, x,y,width,height);
int normalWidth = original.getWidth(), normalHeight = original.getHeight();
int smallWidth = normalWidth/15, smallHeight = normalHeight/15;
Bitmap small = getResizedBitmap(original, smallWidth, smallHeight);
Bitmap pixelated = getResizedBitmap(small, normalWidth, normalHeight);
//Overlay the pixelated bitmap on top of the original
Bitmap overlayed = overlayBitmaps(originalBitmap, pixelated,x,y, width, height);
}
public Bitmap getResizedBitmap(Bitmap bm, int newWidth, int newHeight) {
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
return Bitmap.createBitmap(
bm, 0, 0, width, height, matrix, false);
}
public static Bitmap overlayBitmaps(Bitmap bmp1, Bitmap bmp2, int x, int y, int width, int height) {
Bitmap bmOverlay = Bitmap.createBitmap(bmp1.getWidth(), bmp1.getHeight(), bmp1.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp1, new Matrix(), null);
//If you know the background in transparent or any specific color
//Then you can color the region before overlaying the pixelated bitmap
Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.TRANSPARENT);
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OUT));
mPaint.setAntiAlias(true);
canvas.drawRect(x,y, x+width,y+height, mPaint);
//Overlay the pixelated bitmap
canvas.drawBitmap(bmp2, x, y, null);
return bmOverlay;
}

Modifying bitmap is very slow...Is there any other way for this?

I am here trying to convert my current bitmap in black and white bitmap by writing following method.But it takes very long time to convert because of its for loop of every pixels.Am i wrong here any where? or is there any other way to do this?..Help will be appreciated.Thank you.
My Code:
public Bitmap convert(Bitmap src) {
final double GS_RED = 0.299;
final double GS_GREEN = 0.587;
final double GS_BLUE = 0.114;
int A, R, G, B;
final int width = src.getWidth();
final int height = src.getHeight();
int pixels[] = new int[width * height];
int k = 0;
Bitmap bitmap = Bitmap.createBitmap(width, height, src.getConfig());
src.getPixels(pixels, 0, width, 0, 0, width, height);
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
int pixel = pixels[x + y * width];
A = Color.alpha(pixel);
R = Color.red(pixel);
G = Color.green(pixel);
B = Color.blue(pixel);
R = G = B = (int) (GS_RED * R + GS_GREEN * G + GS_BLUE * B);
pixels[x + y * width] = Color.argb(
A, R, G, B);
}
}
bitmap.setPixels(pixels, 0, width, 0, 0, width, height);
return bitmap;
}

You can easily convert rgb image to grayscale using this method without looping through all pixels
public Bitmap toGrayscale(Bitmap bmp)
{
int originalwidth, originalheight;
originalheight = bmp.getHeight();
originalwidth = bmp.getWidth();
Bitmap bmpGrayscale = Bitmap.createBitmap(originalwidth, originalheight, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(bmpGrayscale);
Paint paint = new Paint();
ColorMatrix cm = new ColorMatrix();
cm.setSaturation(0);
ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
paint.setColorFilter(f);
c.drawBitmap(bmp, 0, 0, paint);
return bmpGrayscale;
}

Android add subtle noise to Bitmap

Anyone know how to add subtle noise to grayscale image?
I have a grayscale image that I want to add some subtle black and white noise to. Anyone know how to do this?
I'm currently using this method, but this is just generating random colors and swapping existing pixels with those colors. How can I add some subtle black and white noise to only SOME pixels on a bitmap?
public static Bitmap applyFleaEffect(Bitmap source) {
// get source 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);
// create a random object
Random random = new Random();
int index = 0;
// 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 random color
int randColor = Color.rgb(random.nextInt(255),
random.nextInt(255), random.nextInt(255));
// OR
pixels[index] |= randColor;
}
}
// output bitmap
Bitmap bmOut = Bitmap.createBitmap(width, height, source.getConfig());
bmOut.setPixels(pixels, 0, width, 0, 0, width, height);
return bmOut;
}
}
UPDATE: Adding complete code to show grayscale step, and attempted noise step
//First, apply greyscale to make Image black and white
Bitmap bmpGrayscale = Bitmap.createBitmap(width, height, mBitmap.getConfig());
Canvas c = new Canvas(bmpGrayscale);
Paint paint = new Paint();
ColorMatrix cm = new ColorMatrix();
cm.setSaturation(0);
ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
paint.setColorFilter(f);
//Apply noise after grayscale
int[] pixels = new int[width * height];
bmpGrayscale.getPixels(pixels, 0, width, 0, 0, width, height);
// a random object
Random random = new Random();
int index = 0;
// Note: Declare the c and randColor variables outside of the for loops
int co = 0;
int randColor = 0;
// iteration through pixels
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
if (random.nextInt(101) < percentNoise) {
// Skip this iteration a certain percentage of the time
continue;
}
// get current index in 2D-matrix
index = y * width + x;
co = random.nextInt(255);
randColor = Color.rgb(co, co, co);
pixels[index] |= randColor;
}
}
// output bitmap
mBitmap = Bitmap.createBitmap(width, height, bmpGrayscale.getConfig());
mBitmap.setPixels(pixels, 0, width, 0, 0, width, height);
c.drawBitmap(mBitmap, 0, 0, paint);
return bmpGrayscale;
}

First, randColor is not likely to be a gray-scale color with your code. To generate a random, gray-scale color:
int c = random.nextInt(255);
int randColor = Color.rgb(c, c, c);
With that in mind, here is how I would re-write your code (note: adjust the percentNoise parameter to your liking):
public static Bitmap applyFleaEffect(Bitmap source, int percentNoise) {
// get source 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);
// create a random object
Random random = new Random();
int index = 0;
// Note: Declare the c and randColor variables outside of the for loops
int c = 0;
int randColor = 0;
// iterate through pixels
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
if (random.nextInt(101) < percentNoise) {
// Skip this iteration a certain percentage of the time
continue;
}
// get current index in 2D-matrix
index = y * width + x;
// get random color
c = random.nextInt(255);
randColor = Color.rgb(c, c, c);
pixels[index] |= randColor;
}
}
Bitmap bmOut = Bitmap.createBitmap(width, height, source.getConfig());
bmOut.setPixels(pixels, 0, width, 0, 0, width, height);
return bmOut;
}

How can i to get color/alpha of pixel from Sprite in andengine?

How can i to get color/alpha of pixel from Sprite in andengine without creating any additional Bitmap?

I solved this problem by using this function
private void loadObjectsMask()
{
InputStream in = null;
Bitmap maskForObjects=null;
try {
final BitmapFactory.Options decodeOptions = new BitmapFactory.Options();
decodeOptions.inPreferredConfig = Bitmap.Config.ARGB_4444;
in = GameActivity.this.getAssets().open("images/" + BACKGROUND_PATH + getObjectImgFile());
maskForObjects = BitmapFactory.decodeStream(in, null, decodeOptions);
} catch (final IOException e) {
} finally {
StreamUtils.close(in);
}
if (maskForObjects != null)
{
objectsMask=new byte[maskForObjects.getWidth()][maskForObjects.getHeight()];
for(int pw=0;pw<maskForObjects.getWidth();++pw)
{
for(int ph=0;ph<maskForObjects.getHeight();++ph)
{
objectsMask[pw][ph]=(byte)(Color.alpha(maskForObjects.getPixel(pw, ph))==0?0:1);
}
}
maskForObjects.recycle();
System.out.printf("Bitmap size %d %d\n", maskForObjects.getWidth(),maskForObjects.getHeight());
}
else System.out.printf("Bitmap size error\n");
}

have a look this method, this method are used to effect on each pix
public Bitmap invert(Bitmap src) {
// image size
int width = src.getWidth();
int height = src.getHeight();
// create output bitmap
Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig());
// 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);
// set new pixel color to output image
bmOut.setPixel(x, y, Color.argb(A, 255-R, 255-G, 255-B));
}
}
// return final image
return bmOut;
}
To convert Gray Scale
public static Bitmap toGrayscale(Bitmap bmpOriginal)
{
int width, height;
height = bmpOriginal.getHeight();
width = bmpOriginal.getWidth();
Bitmap bmpGrayscale = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
Canvas c = new Canvas(bmpGrayscale);
Paint paint = new Paint();
ColorMatrix cm = new ColorMatrix();
cm.setSaturation(0);
ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
paint.setColorFilter(f);
c.drawBitmap(bmpOriginal, 0, 0, paint);
return bmpGrayscale;
}

Replace black color in bitmap with red

How can I replace the black color in a bitmap with red (or any other color) programmatically in Android (ignoring transparency)? I can replace the white color in the bitmap with a color already but it somehow does not work with black.
Thanks for help.

Get all the pixels in the bitmap using this:
int [] allpixels = new int [myBitmap.getHeight() * myBitmap.getWidth()];
myBitmap.getPixels(allpixels, 0, myBitmap.getWidth(), 0, 0, myBitmap.getWidth(), myBitmap.getHeight());
for(int i = 0; i < allpixels.length; i++)
{
if(allpixels[i] == Color.BLACK)
{
allpixels[i] = Color.RED;
}
}
myBitmap.setPixels(allpixels,0,myBitmap.getWidth(),0, 0, myBitmap.getWidth(),myBitmap.getHeight());

This works for me
public Bitmap replaceColor(Bitmap src,int fromColor, int targetColor) {
if(src == null) {
return null;
}
// Source image size
int width = src.getWidth();
int height = src.getHeight();
int[] pixels = new int[width * height];
//get pixels
src.getPixels(pixels, 0, width, 0, 0, width, height);
for(int x = 0; x < pixels.length; ++x) {
pixels[x] = (pixels[x] == fromColor) ? targetColor : pixels[x];
}
// create result bitmap output
Bitmap result = Bitmap.createBitmap(width, height, src.getConfig());
//set pixels
result.setPixels(pixels, 0, width, 0, 0, width, height);
return result;
}
Now set your bit map
replaceColor(bitmapImg,Color.BLACK,Color.GRAY )
For better view please check this Link

#nids : Have you tried replacing your Color to Color.TRANSPARENT ? That should work...