JPEG Manipulation

I need a programmer who knows about Jpeg images. We have a selection of photos in Jpeg format. They will all be either 360x360, 360x260 or 260x360. I need a program which can read in each of the files in turn, and create a watermarked image and a thumbnail. The watermark will be slightly different depending on the orientation of the image. I admit to having absolutely no idea of what will be involved with this, so can you give me an idea of how much time you think it will take to develop this program, and how much you expect it to cost. If you need more details please email me.