Question

Im currently working on a program which applies edge detection to an area of the preview frame. I have used previewcallback and got my cropped bitmap, have converted to grayscale using the following method.

int height1=120;
int width2=120;

            final Bitmap resizedBitmap = Bitmap.createBitmap(bmp, 260, 15, 
                    width2, height1);
            try {
                int bWidth = resizedBitmap.getWidth();
                int bHeight = resizedBitmap.getHeight();
                int[] pixels = new int[bWidth * bHeight];
                resizedBitmap.getPixels(pixels, 0, bWidth, 0, 0, bWidth, bHeight);
                for (int y = 0; y < bHeight; y++){
                    for (int x = 0; x < bWidth; x++){
                        int index = y * bWidth + x;
                        int R = (pixels[index] >> 16) & 0xff;     //bitwise shifting
                        int G = (pixels[index] >> 8) & 0xff;
                        int B = pixels[index] & 0xff;
                        int gray = (int) (.299 * R + .587 * G + .114 * B);
                    }
                }

I am very new to this, and would like to know whether gray is a 2D array of 120×120 pixels, or whether the value of gray is just being overwritten for each loop.

Apologies if this is very basic

Answer 1

Well, maybe I’m missing something, but as far as I can see gray is overwritten. You’d need something like

int[][] gray = new int[width][height];
// start loop

In the Loop:

gray[x][y] = ...;