diff --git a/digital_image_processing/filters/bilateral_filter.py b/digital_image_processing/filters/bilateral_filter.py new file mode 100644 index 000000000..753d6ddb7 --- /dev/null +++ b/digital_image_processing/filters/bilateral_filter.py @@ -0,0 +1,88 @@ +""" +Implementation of Bilateral filter + +Inputs: + img: A 2d image with values in between 0 and 1 + varS: variance in space dimension. + varI: variance in Intensity. + N: Kernel size(Must be an odd number) +Output: + img:A 2d zero padded image with values in between 0 and 1 +""" + +import cv2 +import numpy as np +import math +import sys + + +def vec_gaussian(img: np.ndarray, variance: float) -> np.ndarray: + # For applying gaussian function for each element in matrix. + sigma = math.sqrt(variance) + cons = 1 / (sigma * math.sqrt(2 * math.pi)) + return cons * np.exp(-((img / sigma) ** 2) * 0.5) + + +def get_slice(img: np.ndarray, x: int, y: int, kernel_size: int) -> np.ndarray: + half = kernel_size // 2 + return img[x - half : x + half + 1, y - half : y + half + 1] + + +def get_gauss_kernel(kernel_size: int, spatial_variance: float) -> np.ndarray: + # Creates a gaussian kernel of given dimension. + arr = np.zeros((kernel_size, kernel_size)) + for i in range(0, kernel_size): + for j in range(0, kernel_size): + arr[i, j] = math.sqrt( + abs(i - kernel_size // 2) ** 2 + abs(j - kernel_size // 2) ** 2 + ) + return vec_gaussian(arr, spatial_variance) + + +def bilateral_filter( + img: np.ndarray, + spatial_variance: float, + intensity_variance: float, + kernel_size: int, +) -> np.ndarray: + img2 = np.zeros(img.shape) + gaussKer = get_gauss_kernel(kernel_size, spatial_variance) + sizeX, sizeY = img.shape + for i in range(kernel_size // 2, sizeX - kernel_size // 2): + for j in range(kernel_size // 2, sizeY - kernel_size // 2): + + imgS = get_slice(img, i, j, kernel_size) + imgI = imgS - imgS[kernel_size // 2, kernel_size // 2] + imgIG = vec_gaussian(imgI, intensity_variance) + weights = np.multiply(gaussKer, imgIG) + vals = np.multiply(imgS, weights) + val = np.sum(vals) / np.sum(weights) + img2[i, j] = val + return img2 + + +def parse_args(args: list) -> tuple: + filename = args[1] if args[1:] else "../image_data/lena.jpg" + spatial_variance = float(args[2]) if args[2:] else 1.0 + intensity_variance = float(args[3]) if args[3:] else 1.0 + if args[4:]: + kernel_size = int(args[4]) + kernel_size = kernel_size + abs(kernel_size % 2 - 1) + else: + kernel_size = 5 + return filename, spatial_variance, intensity_variance, kernel_size + + +if __name__ == "__main__": + filename, spatial_variance, intensity_variance, kernel_size = parse_args(sys.argv) + img = cv2.imread(filename, 0) + cv2.imshow("input image", img) + + out = img / 255 + out = out.astype("float32") + out = bilateral_filter(out, spatial_variance, intensity_variance, kernel_size) + out = out * 255 + out = np.uint8(out) + cv2.imshow("output image", out) + cv2.waitKey(0) + cv2.destroyAllWindows()