Android, out of memory converting to black and white

Question

I'm converting some resources to black and white when user touch them. I have this function to do this in my Util java file:

public static Bitmap convertColorIntoBlackAndWhiteImage(Bitmap orginalBitmap) {
    ColorMatrix colorMatrix = new ColorMatrix();
    colorMatrix.setSaturation(0);

    ColorMatrixColorFilter colorMatrixFilter = new ColorMatrixColorFilter(colorMatrix);
    Bitmap blackAndWhiteBitmap = orginalBitmap.copy(Bitmap.Config.ARGB_8888, true);

    Paint paint = new Paint();
    paint.setColorFilter(colorMatrixFilter);

    Canvas canvas = new Canvas(blackAndWhiteBitmap);
    canvas.drawBitmap(blackAndWhiteBitmap, 0, 0, paint);

    return blackAndWhiteBitmap;
}

But sometimes, in some devices I get this error:

java.lang.OutOfMemoryError
at android.graphics.Bitmap.nativeCopy(Native Method)
at android.graphics.Bitmap.copy(Bitmap.java:479)
at com.mygame.util.Util.convertColorIntoBlackAndWhiteImage(Util.java:145)

Line 145 of that function is

Bitmap blackAndWhiteBitmap = orginalBitmap.copy(Bitmap.Config.ARGB_8888, true);

Precisely, I took that function from other stackoverflow answer.

What is happening ?

Thank you

Answer 1

this may help you...

public static Bitmap convertColorIntoBlackAndWhiteImage(Bitmap orginalBitmap) {
    ColorMatrix colorMatrix = new ColorMatrix();
    colorMatrix.setSaturation(0);

    ColorMatrixColorFilter colorMatrixFilter = new ColorMatrixColorFilter(
            colorMatrix);
    Bitmap blackAndWhiteBitmap = orginalBitmap.copy(
            Bitmap.Config.ARGB_8888, true);
    // Recycle the Bitmap and free the memory once you copied into new
    // Bitmap
    orginalBitmap.recycle();
    orginalBitmap = null;
    // still problem exists call
    // System.gc();
    // System.gc();

    Paint paint = new Paint();
    paint.setColorFilter(colorMatrixFilter);

    Canvas canvas = new Canvas(blackAndWhiteBitmap);
    canvas.drawBitmap(blackAndWhiteBitmap, 0, 0, paint);

    return blackAndWhiteBitmap;
}

and it seems like you are trying to convert Image into gray color. try this...

    public static Bitmap toGrayBitmap(Bitmap bitmap) {
        if (bitmap == null || bitmap.isRecycled()) {
            return null;
        }
        final int width = bitmap.getWidth();
        final int height = bitmap.getHeight();

        Bitmap canvasBitmap = Bitmap.createBitmap(width, height,
                Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(canvasBitmap);
        canvas.drawARGB(0, 0, 0, 0);

        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setColor(Color.WHITE);
        ColorMatrix colorMatrix = new ColorMatrix();
        colorMatrix.setSaturation(0);
        ColorMatrixColorFilter filter = new ColorMatrixColorFilter(
                colorMatrix);
        paint.setColorFilter(filter);

        canvas.drawBitmap(bitmap, 0, 0, paint);
        bitmap.recycle(); // do it if still problem exists

        return canvasBitmap;
    }

Answer 2

While working with Bitmaps you should care about memory consumption (specially for devices with large screen and high resolution).

Create a bitmap and recycle that every time you want to convert image.

From android docs:

Bitmaps take up a lot of memory, especially for rich images like photographs. For example, the camera on the Galaxy Nexus takes photos up to 2592x1936 pixels (5 megapixels). If the bitmap configuration used is ARGB_8888 (the default from the Android 2.3 onward) then loading this image into memory takes about 19MB of memory (2592*1936*4 bytes), immediately exhausting the per-app limit on some devices.

Read this:

http://developer.android.com/training/displaying-bitmaps/load-bitmap.html