CODEWITHSUNDEEP
androidbitmap
user2068874
user2068874

Reputation: 11

How to check fast the color of the pixels on a bitmap in android

I go through a bitmap in android and i want to get a the color of each pixel and count it if it has a certain value i.e if it is brown.

I use the following code. The code works but it is extremely slow due to the big number of pixels in the image, which of course I need for correct results.

for(int i =  1; i <= 100; i++){
    for(int j = 1; j <= 100; j++) {
        int pixel =  bitmap.getPixel(i,j);

        R1 = Color.red(pixel);
        G1 = Color.green(pixel);
        B1 = Color.blue(pixel);

        if((R1 == 155) && (G1 == 155) && (B1 == 155)) {
            countthecolor = countthecolor + 1;
        }
    }    
}

Upvotes: 0

Views: 2214

Answers (2)

Amulya Khare
Amulya Khare

Reputation: 7698

You can try to use getPixels which returns a large array of length = bitmap.width * bitmap.height.

Then you can loop through this array and perform your operation. This will be a little faster however, now you will have to manage your memory since you already have the bitmap and now this array in the memory. So I recommend to recycle the bitmap if you don't need it anymore.

int[] pixels = new int[bitmap.getWidth() * bitmap.getHeight()];
bitmap.getPixels(pixels, 0, bitmap.getWidth(), x, y, myBitmap.getHeight(), myBitmap.getWidth());

You can further optimize your loop using bitwise operations to get the individual RGB values (note for alpha may or may not be there):

            Alpha = (pixel & 0xff000000)  
            R1 = (pixel >> 16) & 0xff;
            G1 = (pixel >> 8) & 0xff;
            B1 = (pixel & 0xff);

May want to take a look at this!

Upvotes: 2

f2prateek
f2prateek

Reputation: 2084

Calling getPixel for each each pixel will take a while. getPixels will let you perform calculations on a row of pixels at once.

Upvotes: 0

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