/** Sets a rectangle inside the image with the specified value. */ public static void fillRectangle( ImageInt8 img, int value, int x0, int y0, int width, int height) { int x1 = x0 + width; int y1 = y0 + height; for (int y = y0; y < y1; y++) { for (int x = x0; x < x1; x++) { if (img.isInBounds(x, y)) img.set(x, y, value); } } }
/** * Fills the whole image with the specified pixel value * * @param img An image. * @param value The value that the image is being filled with. */ public static void fill(ImageInt8 img, int value) { final int h = img.getHeight(); final int w = img.getWidth(); byte[] data = img.data; for (int y = 0; y < h; y++) { int index = img.getStartIndex() + y * img.getStride(); for (int x = 0; x < w; x++) { data[index++] = (byte) value; } } }
/** * Computes the mean squared error (MSE) between the two images. * * @param imgA first image. Not modified. * @param imgB second image. Not modified. * @return error between the two images. */ public static double computeMeanSquaredError(ImageInt8 imgA, ImageInt8 imgB) { final int h = imgA.getHeight(); final int w = imgA.getWidth(); double total = 0; for (int y = 0; y < h; y++) { for (int x = 0; x < w; x++) { double difference = imgA.get(x, y) - imgB.get(x, y); total += difference * difference; } } return total / (w * h); }
/** * Sets each value in the image to a value drawn from an uniform distribution that has a range of * min <= X < max. */ public static void randomize(ImageInt8 img, Random rand, int min, int max) { final int h = img.getHeight(); final int w = img.getWidth(); int range = max - min; byte[] data = img.data; for (int y = 0; y < h; y++) { int index = img.getStartIndex() + y * img.getStride(); for (int x = 0; x < w; x++) { data[index++] = (byte) (rand.nextInt(range) + min); } } }
/** Flips the image from top to bottom */ public static void flipVertical(ImageInt8 img) { int h2 = img.height / 2; for (int y = 0; y < h2; y++) { int index1 = img.getStartIndex() + y * img.getStride(); int index2 = img.getStartIndex() + (img.height - y - 1) * img.getStride(); int end = index1 + img.width; while (index1 < end) { int tmp = img.data[index1]; img.data[index1++] = img.data[index2]; img.data[index2++] = (byte) tmp; } } }