Need help w/ question based on Copying Pixels

[Track13]

A Picture has H rows of Pixels, W columns of Pixels, and W is an even number, like W is 2N. Here, N is the whole number that is exactly 1/2 of W. How many pixels are copied when the Picture is mirrored along the vertical line through its middle?

I know the equation is (Width * Height) / 2
I wrote a program to keep count of all the pixels.
I tested different pictures to see if I would get the same answer but, I didn't.
Clearly each picture has different number of pixels.
Am I on the right track with the question?

[JosAH]

All the pixels in the image are copied; try it with a minimal image: 1 row by 2 columns; both pixels are swapped.

kind regards,

Jos

[Track13]

So I should add another loop to through the columns again?

[JosAH]

So I should add another loop to through the columns again?

Why?

kind regards,

Jos