well you can try using unform thumbnail feature if your using image magick but I am not sure 104 x 78 will be uniform. Center crops are usually 120 x 70 without distortion using that thing.
Thumbnails are built with a threshold like say normally 100. Meaning the thumbnail if your image is 640x480 your thumbnail would be 100x75 or if your image is 480x640 your thumbnail would be 75x100 as the aspect ratio needs to be kept or your image is distorted.
Linear Mode
