Develop Reference

How to pixelize a bitmap in android

I have been searching but i did not find a question about how to pixelize a bitmap in android
Example
Note that i dont mean blur

You could just try and resize that image to a smaller version (and then back up if you need it at the same size as the original for some reason)
{
Bitmap original = ...;
//Calculate proportional size, or make the method accept just a factor of scale.
Bitmap small = getResigetResizedBitmap(original, smallWidth, smallHeight);
Bitmap pixelated = getResigetResizedBitmap(small, normalWidth, normalHeight);
//Recycle small, recycle original if no longer needed.
}
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;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// "RECREATE" THE NEW BITMAP
Bitmap resizedBitmap = Bitmap.createBitmap(
bm, 0, 0, width, height, matrix, false);
return resizedBitmap;
}
The code is from here

The simplest way to pixelate the image would be to scale image down using "nearest neighbour" algorithm, and then scale up, using the same algorithm.
Filtering over the image trying to find an average takes much more time, but does not actually give any improvements in result quality, after all you do intentionally want your image distorted.

How to change bitmap height and width programmatically in android?

I want to resize the bitmap height & width into same as the user device width & height.So please help me if u know the code.Thank You !
This is my code:
Bitmap bm = BitmapFactory.decodeResource(getResources(),R.drawable.nature);
DisplayMetrics metrics = getApplicationContext().getResources().getDisplayMetrics();
width = metrics.widthPixels;
height=metrics.heightPixels;
But it was not working

Try to use this method:
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
// GET CURRENT SIZE
int width = bm.getWidth();
int height = bm.getHeight();
// GET SCALE SIZE
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// "RECREATE" THE NEW BITMAP
Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);
return resizedBitmap;
}

Bitmap.createScaledBitmap works great. As the document:
Creates a new bitmap, scaled from an existing bitmap, when possible. If the specified width and height are the same as the current width and height of the source bitmap, the source bitmap is returned and no new bitmap is created.

Why my Bitmap after scaling seems empty

I am trying to scale a Bitmap, doubling its size.
But after the scaling the bitmap shows empty, all plain gray...
here is the code:
Matrix matrix = new Matrix();
// resize the bit map
matrix.postScale(2, 2);
// recreate the new Bitmap and set it back
Bitmap bm2=Bitmap.createBitmap(bm, 0, 0, bm.getWidth(), bm.getHeight(), matrix, true);
//bm.recycle();
EDIT EDIT EDIT EDIT EDIT
I figured it out it's memory issue, if I do it with small images it works fine.
Still the problem remains with large pictures!!!
Thanks for any suggestion!!!

As from the Bitmap Doc it is clearly saying that Bitmap.createBitmap() returns the same bitmap or part of the source bitmap.So may be here it returns the same bitmap object.But here you are recycling it
bm.recycle();
thats why you are getting null
Use this method
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
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);
Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height,
matrix, false);
return resizedBitmap;
}
and pass width as 1920 and height as 2560

how to resize the image and its quality not be change in android?

I am creating an application and want to setup Image . I do not want the images in same size, but same image quality. how to resize that image but same image quality in android ?
i'm using this method to resize the image
Bitmap myBitmap = BitmapFactory.decodeFile(imgFile
.getAbsolutePath());
int h = myBitmap.getHeight() / 20;
int w = myBitmap.getWidth() / 20;
Bitmap scaled = Bitmap.createScaledBitmap(myBitmap, w, h,
true);
imageTab.setImageBitmap(scaled);

Pass btimap you want to resize and size in which you want it to resize in following method
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth)
{
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// CREATE A MATRIX FOR THE MANIPULATION
Matrix matrix = new Matrix();
// RESIZE THE BIT MAP
matrix.postScale(scaleWidth, scaleHeight);
// "RECREATE" THE NEW BITMAP
Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);
return resizedBitmap;
}

Your requirement makes no sense. Whenever you resize it the quality will be changed. Downscaling will make your image lose image data like thin lines etc, and upscaling will make your image blurred and lose clarity.
This is because you only have so much image data with you, and you cannot arbitrarily change the amount of data you have to produce good quality images.
That said, using a format like PNG over JPG can help you save some of the quality at least, as JPG compresses the data even more.

Here is code snippet ..
private static BufferedImage resizeImage(BufferedImage originalImage, int type){
BufferedImage resizedImage = new BufferedImage(IMG_WIDTH, IMG_HEIGHT, type);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, IMG_WIDTH, IMG_HEIGHT, null);
g.dispose();
return resizedImage;
}
BufferedImage resizeImagePng = resizeImage(originalImage, type);
ImageIO.write(resizeImagePng, "png", new File("Image PAth"));

Out of memory during loading images taken with the camera

I am loading an image scale it to screen size and after that the user can draw some text on it using his hand.
After that user can save it to SD card. I need to save it to same width and height as original image has. For others sample image it is working fine. But when i am loading the image captured by camera and once i draw something on draw. I try to scale image back to original height and width but it is giving Exception "Out of Memory Exception" for all the images captured by camera. The code is as follows:
private void saveView(View view) {
Bitmap b = Bitmap.createBitmap(view.getWidth(), view.getHeight(),
Bitmap.Config.ARGB_8888);
String filePath="/sdcard/";
Canvas c = new Canvas(b);
view.draw(c);
float scaleHeight=((float)getHeight()/b.getHeight());
float scaleWidth=((float)getWidth()/b.getWidth());
Matrix matrix=new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Log.e("getWidth()", ":"+getWidth());
Log.e("getHeight()", ":"+getHeight());
**//Giving Exception at below Line as i am trying to scat it to origenal size.
b=Bitmap.createBitmap(b,0,0,b.getWidth(),b.getHeight(),matrix,true);**

You need to resize your bitmap as below.+
Bitmap resizedBitmap = getResizedBitmap(myBitmap, 150, 150);
and the method
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// create a matrix for the manipulation
Matrix matrix = new Matrix();
// resize the bit map
matrix.postScale(scaleWidth, scaleHeight);
// recreate the new Bitmap
Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height,
matrix, false);
return resizedBitmap;
}