Revision history [back]

if it is a version conflict, libraries missing,

BOTH of it !

with opencv3, imread(), imwrite() and friends have been moved from highgui to a seperate imgcodecs module.

try:

find_package( OpenCV COMPONENTS core imgproc imgcodecs highgui REQUIRED )

also, please use http://docs.opencv.org/master/ , not the outdated 2.4 docs.