dpi when scanning photographs.

[flobadob]

I was scanning a few photos for someone recently and while clicking about I noticed that if I went to custom settings on the scanner I could change the dpi to a maximum of 600 even though it had been set automatically to 150. I've looked up that dpi is the same as pixels from what I can make out.

What I'm wondering is, does it affect any future use of the images if I change the dpi or is it always the case that the dpi should be set as high as possible when scanning photos? Thanks.

[snags]

The more dpi (dots per inch) the higher the quality/detail of the resulting scan: useful if you want to print from and/or enlarge...

[ChuckFickens]

^ But bad if you want to email the scans as they will be huge files.

You have to choose the DPI based on what you want to do with the final scan.

[scotman]

To a certain extent it depends on the state of the photo and what the scan will be used for.
If it is for showing on web pages then high resolution is not really needed. If it will be printed or manipulated (Photoshop etc) then the higher resolution will probably be better

[snags]

Of course the higher the resolution the larger the file size, which you might want to consider if you're emailing the images...

[Haggisdj]

I have external drives that I keep my original photos on, at the largest size I can. I can then resize them, etc. for uploading to Facebook or to email. You can always take the quality out but you can't put it back in unless you rescan...

[flobadob]

Most likely I will want to re-print them at some stage as photographs, using the saved scanned image files, otherwise I will just store them on the computer.

[woofgang]

If you have got one chance to scan the photo then do it in as high a res as possible, min 300 dpi. You can always reduce the res for web use and emailing (make sure you save the reduced version with a different filename) but you can't increase it.

[scotman]

If it was me I would take the highest resolution bitmap scan you can manage and store that. Any further work could be done using copies of that original file.

[flobadob]

I see what you are saying as the photos at 150dpi are around 90KB but the ones scanned at 600dpi are up around 1MB. If the only downside is the fact that the file size will be larger I probably should scan at 600dpi from now on. Annoyingly most photos I've scanned are at 150dpi. 600dpi is a much slower scan but I'd say it's worth it for the better quality image. Thanks.