I am trying to train custom object classifier in Darknet YOLO v2 https://pjreddie.com/darknet/yolo/
I gathered a dataset for images most of them are 6000 x 4000 px and s
You don't need to resize your database images. PJReddie's YOLO architecture does it by itself keeping the aspect ratio safe (no information will miss) according to the resolution in .cfg file. For Example, if you have image size 1248 x 936, YOLO will resize it to 416 x 312 and then pad the extra space with black bars to fit into 416 x 416 network.