DPI vs. megapixel simple questions / scan old pictures at 'good quality, etc.
Posted on 2004-10-06
This may be basic stuff for you guys, but please help me out! I have a 4 megapixel Canon SD410 camera whose pictures at the highest / finest settings takes jpgs that are about 2 meg in size.
I have a scanner (HP scanjet 5100c) that I want to use to scan in 4 x 6 photographs so all my pictures are digitized. When I scan at say, 300 dpi, the file size is a few hundred KB. what is the 'native' DPI of a 4 megapixel camera?
And for digitizing 4 x 6 pictures taken with a traditional camera, what is the 'right' / best dpi. storage space is not an issue. But I don't want to scan at 4000DPI just to have a large file. I've tried scanning on at 200 vs. 300 DPI and really can't see a difference when I zoom in. May be the picture I am experimenting with is blurry?
I'd hate to spend hours scanning in pics at 200 DPI when it really should be 600. or scan in at 600 and find out later that 300 DPI is the effective quality of a 4x6 print (what is the 'weak link' in the scanning chain? The print or the DPI you scan it in at?).
I've heard people argue that it matters what you want to do with the picture. I don't know right now.... so I want to get the best I can expect, starting with the 4 x 6 original print. They likely will sit on the hard drive and go no where. but I might want to make a poster one day and hate to hear that the scanned image yielded a lower quality poster than the 4 x 6. Yes, I know - you enlarge a 4 x 6 too much and it gets grainy. I accept that and just want the same result from a digitized image...