Finally, after wasting hours of research. One mistake that I was doing is, while converting, setting the pixel 1242px was automatically changing the other dimension to 2209px, and apple portal was rejecting it.
Be careful while resizing.
NightCoder29
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution