Consider the quality

When I visit a photography portfolio or even a showcase, I expect all the time to be able to see the pictures in full size if I click on them and it would better be huge. I want the pictures to look good and fit my screen if I would like to have it as a desktop background. And not only about this but if I want to see all the details, I canandt do it properly on a small picture.
To avoid keeping the visitors wait too much, have two versions of each picture you can resize them with a JavaScript too. This way if somebody is interested in seeing one of your pictures larger, he knows that this comes with the price of loading time.