Merge "Use median of border brightness as rotation background color" into main

        final int pixelStride = plane.getPixelStride();

        final int rowStride = plane.getRowStride();

        final int sampling = 10;

        final int[] borderLumas = new int[(width + height) * 2 / sampling];

        final int[] histogram = new int[256];

        // Grab the top and bottom borders.

        int i = 0;

        for (int x = 0, size = width - sampling; x < size; x += sampling) {

            borderLumas[i++] = getPixelLuminance(buffer, x, 0, pixelStride, rowStride);

            borderLumas[i++] = getPixelLuminance(buffer, x, height - 1, pixelStride, rowStride);

            final int topLm = getPixelLuminance(buffer, x, 0, pixelStride, rowStride);

            final int bottomLm = getPixelLuminance(buffer, x, height - 1, pixelStride, rowStride);

            histogram[topLm]++;

            histogram[bottomLm]++;

        }

        // Grab the left and right borders.

        for (int y = 0, size = height - sampling; y < size; y += sampling) {

            borderLumas[i++] = getPixelLuminance(buffer, 0, y, pixelStride, rowStride);

            borderLumas[i++] = getPixelLuminance(buffer, width - 1, y, pixelStride, rowStride);

            final int leftLm = getPixelLuminance(buffer, 0, y, pixelStride, rowStride);

            final int rightLm = getPixelLuminance(buffer, width - 1, y, pixelStride, rowStride);

            histogram[leftLm]++;

            histogram[rightLm]++;

        }

        ir.close();

        // Get "mode" by histogram.

        final int[] histogram = new int[256];

        int maxCount = 0;

        int mostLuma = 0;

        for (int luma : borderLumas) {

            final int count = ++histogram[luma];

            if (count > maxCount) {

                maxCount = count;

                mostLuma = luma;

        // Find the median from histogram.

        final int halfNum = (width + height) / sampling;

        int sum = 0;

        int medianLuminance = 0;

        for (i = 0; i < histogram.length; i++) {

            sum += histogram[i];

            if (sum >= halfNum) {

                medianLuminance = i;

                break;

            }

        }

        return mostLuma / 255f;

        return medianLuminance / 255f;

    }

    /** Returns the luminance of the pixel in 0~255. */