Why subtract 1 in flip?

[moekaungkin11]

Why 1 is subtract in adjusting the boxes coordinates after horizontal flipping?What is 1 mean? I thought this already satisfied without subtracting 1.Am i wrong?
The code is....
new_boxes[:, 0] = image.width - boxes[:, 0] - 1
new_boxes[:, 2] = image.width - boxes[:, 2] - 1

[slmatrix]

image.width is not a zero indexed value; that is why subtraction by one is done. It ensures the horizontal flip is within the bounds of the image tensor.