Here comes the techno Geek part: depending on the slide film, there are from 1500 to 3500 grains per inch. The slower the film, the smaller the grain, and more grains per inch. Kodachrome 200 was about 2000 grains per inch. To capture teh full fidelity, you need to scan at that, so for a 35mm slide you are looking at about 5.2 MegaPixels.
This is slow and time consuming to do. When I converted some 2500 slides I bought a very expensive scanner which had an auto feed feature, it was a Japanese brand, maybe Fuji, been a while. It took standard Kodak Carasol trays. I would load one up with the 100 photos, and launch it, and load the spare tray. That can take a bit, becasue you want to blow any dust off, before you load them. Then come back the next day, change the Carasol out, and load slides in the one that just finished. Took most of a month to run them all through.
The compression strategy is that it starts at pixel 0,0, and decides what colors and gray scale that pixel is and records it. Then it goes to 0,1. If things haven’t changed it goes to 0,2, and analyzes it. If it hasn’t changed, it move on to the next one. If it gets to 0,5 and something is different then it records the location and the new data. And ,moves on until it finds another change.
Things that are pretty uniform can scan quickly, things that have its of changes take longer. Sometimes a lot longer.
There is no quick, easy way to do it and capture the potential of the film.
