I have a question about an answer on Genealogy & Family History Stack Exchange. According to this blog post found at the Library of Congress:
You can scan [photos] at a higher resolution [I'm assuming higher than 600 ppi]. However, in most cases, all you will see are the defects [on those same photos].
The blog further states that:
If the original you have to work with is a 4 x 6 inch print, and you scan it at 600 or 1200 pixels per inch, [one] could then make the equivalent of an 8 x 12 inch print, but it’s not likely to give you better quality.
However, the answer to the G&FH question suggests scanning an extremely valuable family photograph at 2400 ppi to do the necessary color separations before using the same photo for the dust jacket of a hypothetical family book. Is this a useful suggestion, or does the Library of Congress advice about not scanning at higher resolutions still apply?
Is this something which makes sense only if you are going to do color separation in an image editing tool, or would there be other reasons to use a higher resolution?
Would the same advice apply to black-and-white and/or color slides? The LoC blog suggests scanning those at extremely high resolutions.