The values of
image[i][j].rgbtGreen are stored as what CS50 defined as a
BYTE, which is actually an unsigned integer of length 8 bits. The maximum value for this data type is
In the lines with the errors, you are trying to assign values outside of this range (i.e.
image[i][j].rgbtGreen, causing this error.
I suggest using debug50 to step through this process and taking a look at each variable before this to see why you're getting values above 255 (you shouldn't be!)
Another problem with you program is that you're changing the original image array as you're going along. While your end result will indeed be a blurred version of the original image, it'll not be what
Hope this helps and do mark this as an answer if it does!