Hi Gerco,
Yes, it is 100% SimpleViewer. Think of Lotus Notes as the file container for photos.
All of the SimpleViewer options are defined on the "Album" form. see Album Layout > Padding.
SimpleViewer will resize images to fit the user's screen, however, it is recommended that you resize your photos to make them load faster.
Here's a tip:
Open an Album form, and click the button in the upper-right corner. Web > Album XML.
You can compare these XML settings to the airtight documentation.
Brian