digital_image_processing/convert_to_negative (#1216)

* digital_image_processing/convert_to_negative

* added doc

* added test code

* Update convert_to_negative.py

digital_image_processing/convert_to_negative.py

@@ -0,0 +1,30 @@
+"""
+    Implemented an algorithm using opencv to convert a colored image into its negative
+"""
+
+from cv2 import imread, imshow, waitKey, destroyAllWindows
+
+
+def convert_to_negative(img):
+    # getting number of pixels in the image
+    pixel_h, pixel_v = img.shape[0], img.shape[1]
+
+    # converting each pixel's color to its negative
+    for i in range(pixel_h):
+        for j in range(pixel_v):
+            img[i][j] = [255, 255, 255] - img[i][j]
+
+    return img
+
+
+if __name__ == "__main__":
+    # read original image
+    img = imread("image_data/lena.jpg", 1)
+
+    # convert to its negative
+    neg = convert_to_negative(img)
+
+    # show result image
+    imshow("negative of original image", img)
+    waitKey(0)
+    destroyAllWindows()