Scanning slides - what size/dpi should I use?

[jmp]

I have borrowed a slide scanner which does batches of slides and I wonder what sort of dpi size I should go for to get a reasonable image? The manual that comes with it is more than slightly confusing to me . Most are holiday photos taken in the 60's and I was planning on scanning to jpg initially and then if I come across one I really want to keep scanning that one as a Tif version.
Can anyone give me any tips please?
Many thanks
Jackie

[McGroger]

I bought a cheap slide scanner early this year and finally got around to scanning about 2,000 old family slides from the 1970s and early 1980s. The scanner's resolution was fixed at 3,200 dpi and gave a picture size of 4,608X3,072 pixels, and a jpg file size of 2mb for each slide. The resultant images were more dependent on the condition of the slides than the resolution, but I think 3,200 dpi was about right for retaining a good quality (if it was there in the first place). I've posted one of about average quality from 1983 (he turns 40 next year  , makes me feel old  ) to an image hosting site in order to give you an idea of the end result: https://ibb.co/cbVKz3J
Peter

[Annbee]

Hello Jackie,

I'm a retired photographer who also had a side hustle repairing photos. Can I ask you what options your scanner are giving you for 'dpi' which means 'ppi (pixels per inch)? Is it something like 300 and 400 and 600 and more dpi/ppi?

EDIT: I just realised you said SLIDES. The following is for prints scans. I'll add slides in a new comment.

300 will give you the same size of the photo you are scanning; so a 4x6 inch photo will stay the same when you print it at 300 dpi/ppi. For a regular snapshot of just vague importance, one which you don't want to enlarge in a print, this might be enough for you. If you are doing a heap of photos and don't have a lot of storage space on your computer (plus a back up) this size will save storage space.

600 is my favourite default size for photos that have significance or might be significant for other people in the future. It's a size which gives you some wriggle room. With 600 a 4x6 inch photo will double in size when you print it at 300dpi/ppi.

By using higher dpi/ppi you are not 'improving' the photo; if it is lacking detail and a bit blurry (like so many 'Dad' photos of the past ) it will probably make those issues even more pronounced. But I always say any photo is better than no photo and go with the size you think might be handy now and later on.

Printing at 300 ppi is the standard to print at and which defines the size for you.

Also, yes, for 'important' photos, I would save as tiff. If you have the disc space, use tiff for all key photos.

I used to say if you are scanning a lot, put them in 3 piles of good (scan at 300ppi, jpeg), better (scan at 400-600ppi, jpeg or tiff) and best (600ppi-1200ppi, tiff).

Does that make any sense for you?

[Annbee]

For slides, 2500-3600 dpi/ppi is considered standard and for larger go to 4000.

I've attached a restored slide here as an example. It was scanned on a professional scanner at high, at 4000, and I was able to produce a very nice 6x8 inch print. I recently had another important slide scanned professionally at a lab and they did it at 6,000 something dpi/ppi! (On a trillion dollar scanner, the results are excellent) I should add that the image attached here is downsized heavily for web use and isn't the print size.

But you may end up with hard drive hogging files if you went really high, especially if you did tiff. So I would think 2500-3600 would be ample for slides you class as medium important. (The image I'm attaching is my husband as a baby with his mother who died just a couple of years after this photo - so worth the high resolution/professional scan for us)

If none of this makes sense to you still, then simply do a few test runs and load them up on your screen and take a look. Just remember that, say, a file of 3600x 2400 pixels (ie  scanned at 3600) would print at 12x8 inches which although might seem like overkill, it's easier to downsize to smaller prints than to enlarge.

Again, if you've got a heap of slides, classify them. You don't have to scan every single one; in fact, I scan only the most important ones.

Hope this helps.

[Annbee]

For those who are interested in this subject, here's longer detailed explanation of scanning sizes on what is now quite an old webpage (not mine).

https://www.scantips.com/basics08.html

There's a link on that page too, to take you to another page to easily calculate sizes. But I'll put the same link here too for easy access.

https://www.scantips.com/calc.html

[jmp]

Thank you everyone for your tips. I will give it a go and come back if I need any more help if I may
Cheers
Jackie

[mrcakey]

Just wanted to add that you should avoid "lossy" image formats like JPEG if you can. If you attempt any sort of image manipulation on your scanned file, it re-codes the image file and every time it does so you lose a little detail.

If you can scan to PNG (common) or TIFF (less common) files and have sufficient capacity on your storage (most will these days), then those formats will retain image integrity if you do any Photoshopping on them.

I'd also second the advice to use a high but not ridiculously high resolution. The higher the resolution, the bigger the file you produce at the end. Generally you get better quality too, but it's a curve of diminishing returns and if you have a lot to do, then higher resolutions take a lot longer.

The other thing I'd say is to practise a fair bit with a few slides to check your workflow. Scanning is an involved process that takes a long time. If you're scanning loads of slides then it's important to iron out any difficulties at the beginning.

(I'm running with the theme now!) Also consider naming conventions for your files. I have a convoluted naming convention for my scans, but you could use a simple one like: date (in YYYYMMDD format), person(s), location, event, separated by semi-colons, e.g.

19680907;Coulson, Andrew; Waters, Ginger; Coulson-Waters wedding; Danbury.PNG

There are also photo organisers you can buy that will attempt to recognise faces and "tag" your photos automagically, but I've personally had limited success with these.