Utility functions

Some functions that can be useful for dealing with coordinates.

Author: pedbrgs

utils/utils.py

@@ -0,0 +1,66 @@
+""" Some functions that can be useful for dealing with coordinates. """
+
+def non_negative(coord):
+    
+    """
+        Sets negative coordinates to zero. This fixes bugs in some labeling tools.
+        
+        Input:
+            coord: Int or float
+            Any number that represents a coordinate, whether normalized or not.
+    """
+    
+    if coord < 0:
+        return 0
+    else:
+        return coord
+    
+def pixel2yolo(dim, pixel_coords):
+    
+    """
+        Transforms coordinates in YOLO format to coordinates in pixels.
+        
+        Input:
+            dim: Tuple or list
+            Image size (width, height).
+            pixel_coords: List
+            Bounding box coordinates in pixels (xmin, ymin, xmax, ymax).
+        Output:
+            yolo_coords: List
+            Bounding box coordinates in YOLO format (xcenter, ycenter, width, height).
+    """
+    
+    dw = 1/dim[0]
+    dh = 1/dim[1]
+    xcenter = non_negative(dw*(pixel_coords[0] + pixel_coords[2])/2)
+    ycenter = non_negative(dh*(pixel_coords[1] + pixel_coords[3])/2)
+    width = non_negative(dw*(pixel_coords[2] - pixel_coords[0]))
+    height = non_negative(dh*(pixel_coords[3] - pixel_coords[1]))
+    
+    yolo_coords = [xcenter, ycenter, width, height]
+    
+    return yolo_coords
+
+def yolo2pixel(dim, yolo_coords):
+    
+    """
+        Transforms coordinates in YOLO format to coordinates in pixels.
+        
+        Input:
+            dim: Tuple or list
+            Image size (width, height).
+            yolo_coords: List
+            Bounding box coordinates in YOLO format (xcenter, ycenter, width, height).
+        Output:
+            pixel_coords: List
+            Bounding box coordinates in pixels (xmin, ymin, xmax, ymax).
+    """
+    
+    xmin = non_negative(round(dim[0] * (yolo_coords[0] - yolo_coords[2]/2)))
+    xmax = non_negative(round(dim[0] * (yolo_coords[0] + yolo_coords[2]/2)))
+    ymin = non_negative(round(dim[1] * (yolo_coords[1] - yolo_coords[3]/2)))
+    ymax = non_negative(round(dim[1] * (yolo_coords[1] + yolo_coords[3]/2)))
+    
+    pixel_coords = [xmin, ymin, xmax, ymax]
+    
+    return pixel_coords