add label precode code

Author: Spritea

precode.py

@@ -0,0 +1,63 @@
+import cv2 as cv
+from pathlib import Path
+import natsort
+import numpy as np
+
+def one_hot_it(label, label_values):
+ """
+ Convert a segmentation image label array to one-hot format
+ by replacing each pixel value with a vector of length num_classes
+
+ # Arguments
+ label: The 2D array segmentation image label
+ label_values
+
+ # Returns
+ A 2D array with the same width and hieght as the input, but
+ with a depth size of num_classes
+ """
+ semantic_map = []
+ for colour in label_values:
+ # colour_map = np.full((label.shape[0], label.shape[1], label.shape[2]), colour, dtype=int)
+ equality = np.equal(label, colour)
+ class_map = np.all(equality, axis=-1)
+ semantic_map.append(class_map)
+ semantic_map = np.stack(semantic_map, axis=-1)
+
+ return semantic_map
+
+def reverse_one_hot(image):
+ """
+ Transform a 2D array in one-hot format (depth is num_classes),
+ to a 2D array with only 1 channel, where each pixel value is
+ the classified class key.
+
+ # Arguments
+ image: The one-hot format image
+
+ # Returns
+ A 2D array with the same width and hieght as the input, but
+ with a depth size of 1, where each pixel value is the classified
+ class key.
+ """
+ x = np.argmax(image, axis=-1)
+ return x
+
+def load_image(path):
+ image = cv.cvtColor(cv.imread(path, 1), cv.COLOR_BGR2RGB)
+ return image
+
+GT_Path = Path("path-to-original-label-images")
+GT_File = natsort.natsorted(list(GT_Path.glob("*.png")), alg=natsort.PATH)
+GT_Str = []
+for i in GT_File:
+ GT_Str.append(str(i))
+
+out_prefix="precoded_label"
+label_values = [[255, 255, 255], [0, 0, 255], [0, 255, 255], [0, 255, 0], [255, 255, 0], [255, 0, 0]]
+for k in range(len(GT_Str)):
+ gt=load_image(GT_Str[k])
+ out=reverse_one_hot(one_hot_it(gt,label_values))
+ out_str=out_prefix+Path(GT_Str[k]).name
+ cv.imwrite(out_str,out)
+ # print("kk")