Good morning Marcia (and list :)),
I would like to some photos at 300% magnification
Quick answer: Right click on the image, select "image" from the menu,
then select "scale image". In both of the "ratio" boxes, enter the
number "3". Click ok. Your image is 300% larger.
Longer answer:The original image is a certain number of pixels (dots) in
width and height. To magnify it, we effectively need to create more
pixels, so we do this by scaling. (Scaling is basically another word
for "measuring" or "measurements" with respect to an original size).
There are a number of ways of working out what the final image will
look like. Some interpolate (work out by estimating the bits between
the original rows and columns), others extrapolate (work it out by
expanding existing pixels) and there are many more ways besides! I
always use cubic as it seems to work best for me
Hope some of this helped. By the way, if you update to a later version
of gimp, you can click on the "image" menu directly instead of
right-clicking on the image first.