The thumbnails are 100x75 and the larger images are 640x480.
To create a set of thumbnails, one way to do it is to create a subdirectory called 'thumbs' and copy all of your images to that. Next, type...
mogrify -resize 100x75 sa*.jpg...and it will turn them all into 100x75 thumbnail images. Then, you can use the thumbnails in a gallery like so and each one accesses the main image just as in the frame below. Like so...
click on an image to see it in the large frame...
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