Upload Distortion

I am Running the ephoto theme trying to use the Next Gen galleries. Here is the issue it does not seem to matter how I upload the photos anything bigger than a thumbnail is pixelated or blurry. I have tried large file, small file, adjusting size in several areas and still no success. I know the pictures are clear because I took them and I have a good idea what I am doing and I use a good camera. Has any body got any suggestions.