DIY Photo Scanning: Maximizing Quality

Lots of people have a photo scanner these days. Most of us will slap an old photo or document on the glass from time to time - and then kind of just hope for the best. Finally, here are the settings - simply explained - for getting what you need from your scanner if you plan on a photo restoration.

Which photo scanners are best?

A lot of us have multi-function fax/copy/scanners that are connected to our computers.  You can get satisfactory results from these combo machines, provided you follow the instructions here.

If you can, use a dedicated machine that lives or dies by the quality of its scans.  We have always used Epson brand scanners in our photo repair work and have never gone wrong.

If in doubt, you can take your photo to a Fedex office and let them worry about the details.  They are not the only people who can help, but they sure blanket the country with their stores so there is bound to be one near you. As at time of writing, Fedex goes as high as 600 dpi (200%).

Dust to Dust

First wash and dry your hands (even better, put on cotton gloves). Oils left on original photos can degrade them over time - and will leave prints on your scanner glass .  It's always best to give the glass a wipe with a cloth and Windex or isopropyl alcohol. If you have a can of air - blow the dust off the glass too. And check the photo for dust while you are at it.

OK. The glass is safely dry and the photo is back on. Go to your computer and poke around and find your "settings" or "preferences" tab. There are really only three setting that you need to worry about and they are: resolution - or dots per inch (or "dpi"); "photo or document"; and "color or black and white".

Resolution matters most in scanning because dpi sets both the quality and size of your image - see more below. Always choose "photo" (not "document") and always check "color" - even if you are scanning a black and white image. Lastly, choose your file path so you can find the scans when you are done, and output to JPEG, best quality.

Best Scanner Resolution for Printing

Scanning Photos Destined for Screens
Your scanner should have a setting for "resolution" and it should give you some choices either in dpi ("dots per inch") or ppi ("pixels per inch") - for all practical purposes they are the same thing. Your choice - depending on your scanner - will be something between 50 and 10,000 dpi.

Scanning at 300 dpi will give you an image that can be printed at the same size as the original.  Can't do better than that can we?

Actually, we can. Very often, there is a lot more detail in a photograph than we can see with the naked eye. So it almost always pays to scan at higher than 300 dpi.  In our work here, we scan at a minimum of 600 dpi which means that an image can be made twice the size of the original.

If you are certain that you only want something as big as the original, then scan at 400 dpi.  That's bigger than the original but gives you some margin if you want to crop off a border or a ragged edge.
A large screen (TV or computer) is around 1920 pixels wide and 1280 pixels high.  If you want an image that will fit comfortably within the computer screen, then something around 600 pixels high should suffice. If you plan on viewing your photo a high definition TV then it will need to be around 1280 or more high.

Now, we need a tiny bit of math to convert your photo size to screen size.  If your photo is 6" x 4" and you scan at 200 dpi (dots per inch) then the resulting digital image will be 1200 pixels x 800 pixels (6 x 200 and 4 x 200).  Perfect!

Keep in mind though that at 200 dpi you will not be able to get a great print.   You would need at least 300 dpi for that.  So, if you are going to go to all the trouble of setting things up for a photo repair or a photo restoration, maybe do two scans: one for screens and one for printing.

Resolution for Negatives and Slides

A stand alone scanner will have a frame that allows you to scan negatives and slides.  (You will need to take the white top plate off your scanner lid for this exercise.)

Make sure the settings are set for negative film or positive film (slides). Take special care with dust on the glass and on the film then scan at a minimum of 2400 dpi.  If you have the patience, choose 4800 dpi.

Scanning documents

Documents can generally be scanned at a maximum of 300 dpi.  Seldom do we have the need to enlarge a document and usually they are just a matter of record. Your scanner should have a "document" setting.

If you plan to frame the document or enlarge it then treat it like a photograph. If you just need to send it to your accountant then 150 dpi should suffice.

Alternatives to Scanning

Some people use their phones to copy an image.  That can work if you want to send it off to, say, get an estimate for photo repair or restoration.

Back in the day, all copying was done with cameras.  And even today, some professionals digitize images using high quality cameras and carefully balanced lighting.

Cameras are faster than scanning and can handle very large images (provided they are flat or laid in a glass sandwich).

Our testing and our experience in retouching photos tells us that a quality scanner is superior to re-photographing the image, although it is more laborious.
Why scan B&W photos in color?
First of all, few images that appear to be black and white are actually devoid of color. Most have a slight, natural tint.

Second, scanning images in color means that three color channels are created - Red, Green and Blue - and this is important should you ever wish to repair the photo or restore it since much of the work is done on these channels separately. In addition, many of the most sophisticated adjustment and restoration tools require an image with all three color channels.

And, sure you have a smaller file size with a black and white photo scan - but these days, disk space is really no longer an issue.