Wrong term in the tutorial "Making your own linear filters!"
In the tutorial "Making your own linear filters!" - http://docs.opencv.org/doc/tutorials/imgproc/imgtrans/filter_2d/filter_2d.html, the term "Convolution" is used with filter2D. This is wrong since filter2D does correlation instead of convolution as said in the API reference http://docs.opencv.org/modules/imgproc/doc/filtering.html, "The function does actually compute correlation, not the convolution:"
Right?
Has already be answered: http://answers.opencv.org/question/26065/filter2d-and-convolutions/
You are right I guess. You could file a bug report to actually change the documentation at the dev forum.