There are many things that can be done to improve pics for display. I always use jpg as it takes up far less room and 'loads' much quicker for the viewer. gif files are more suited to layering (ie for moving banners).

Remember that reducing the size will improve the pic where enlarging it wont.

I have a true 1200dpi color printer also. At times I have had to print a pic supplied to me so that I could re-scan the print at maximum resolution for a satisfactory result.

Some of the scans Gene had for the articles either had 'faults' or were too small but very high resoultion. Enlargement of these to the correct size would have meant dial-up users waiting an age for pages to load. I did the same thing I demonstrated in the scans I posted. Enlarge the item first, then resize the pixels.
I straightened up a few of the pics also, and will do the others in due course. Gene thought a couple of his scans were 'unusable' and they were not actually used in the original articles. I was able to improve them enough to use.

Good software counts for a lot also. If you have Photoshop you can achieve almost anything.