For those of you interested in scanning and making your own archives of precious old photos stick around and read below some tips I have accumulated. I roamed the 'net to find out how best to scan and create my archives. I got terribly confused with conflicting information. So I downloaded, what seemed to me, the most credible information, sifted it, and came up with the following
summary.
Scanning Photos for Genealogists
First of all, there are three basic reasons for scanning your photos.
1) ARCHIVE copies - for long term protection of precious heritage photos and documents.
2) ACCESS copies - for general distribution and viewing on your computer or publishing on a web site.
3) PRINT copies - scanning to print a copy of an existing photo.
The following notes are gleaned mostly from three sources which I recommend for further reading,
Grateful thanks to all for the information published.
General Notes:
* Scan black & white photos as gray image; colour and sepia tone photos as 24 bit colour or greater.
* As a general rule, set the Gamma setting to 1.8 on your scanner software. You can experiment up and down on this but this setting is a good average.
* ppi = pixels per inch; dpi = dots per inch - they are not the same! BUT they are frequently used as interchangeable descriptions. ppi is correctly used to describe your scanning and on-screen viewing processes. This is where some literature uses either or both ppi and dpi.
dpi is correctly used to describe your printer's output.
* Scan at integer intervals. That is, your basic scanner resolution divided by the integers, 1,2,3,4,5, etc. For example for a 600 dpi scanner, use only scanning resolutions of 600, 300, 200, 150, 120, 100, 75,... So whatever we calculate the scan ppi to be, say 280 ppi, then scan at the next
highest integer value which is 300 ppi and 'resample' the image down (check the HELP section of your software) to the desired size in your photo-editing software.
ARCHIVE COPIES
As archiving is probably the most important aspect for genealogists, although we do like to show our ancestors off on the web, this is the one we'll start with. This is the specialisation subject of the Colorado Digitization Project and the Denver Library.
Resolution: Your resolution for scanning will be calculated from the longest dimension of the photograph, measured in inches. Assume our photo is 8" x 6". Aim for 3000 to 5000 pixels across the long dimension. To obtain the ppi resolution for scanning simply divide
3000 by 8" which = 375 ppi and 5000 by 8" which = 625 ppi.
600 ppi is a good average which covers just about all situations and should be your minimum figure for archive copies.
File Format: Save files in TIFF format.
Remember file sizes will be LARGE - make sure you have enough storage room. Storage copies will require ZIP disks as a minimum and CD-ROMS as a preference. Make the saved files 'Read Only'.
DO NOT do any image adjustment to your archive copy. Save another copy for editing if you want to, but the basic scanned image should remain untouched. Remember, editing software is improving all the time and one of your descendants will want an untouched copy in 20 years time when they want to work off your
archives.
ARCHIVES ARE FOR FUTURE GENERATIONS
ACCESS COPIES
Access copies are the copies you will generally use for publishing on your web pages, emailing to family and friends, or use for 'wallpaper' backgrounds on your computer.
Firstly, computer screens have a resolution of 72 ppi. Therefore there is no advantage in scanning at a greater resolution except that some scanner software will only go down as low as 100 ppi and 72 ppi is not an integer divisor - that's OK, no sweat, don't worry. Scan at 100 and resample and resize with your photo-editing software.
OR, probably the best (and easiest) option,
don't re-scan at all. Make a copy of your archive image and resize and resample to the size you want.
Resolution: Resolution will be determined by 1) the finished size on screen you want, 2) the size of your original photo, and 3) the orientation of your original photo, ie portrait or landscape.
Common screen sizes are, in pixels, 640 x 480, 800 x 600, 1024 x 768, 1280 x 1024. You may have a large bells and whistles monitor but if the majority of your viewers have 640 x 480 monitors, you will annoy them no end with photos they have to scroll around to see. So let's set 640 x 480 as our maximum size for scanning purposes - you can adjust the final image size later with your
photo-editing software.
Now, if your original is a 6" x 4" portrait the vertical dimension will be the 6". The screen dimension will be 480 pixels, therefore your scanning resolution will be 480 divided by 6 which = 80 ppi.
If your original is 6" x 4" landscape the horizontal measurement is 6". The screen dimension is 640 pixels and your scanning resolution will be 640 divided by 6 which = 107 ppi.
If you only want to take up half the screen width, that is 320 pixels, then 320 divided by 6 = 53 ppi.
Remember, you can adjust the image size after scanning with your photo-editing software.
File Format: Save files in JPEG (JPG) format. Generally don't use greater than 12:1 compression. Your photo-editing software will ask you this when you save.
Access images are the ones you can really play around with for effect. One of the best editing tools you will use is the Unsharp Mask Filter. A good starting point is to use the settings that follow but do play around, these won't suit every photo. Radius = 1, Amount = 100 to 120%, Threshold = 3 to 5.
PRINT COPIES
This is where I will give you the least information.
Basically, find out the dpi of your printer. I might waste space but I always scan (or resample) for print output at 300 ppi, the nearest integer value to my printer dpi of 360, or 600 dpi if I'm really pushing it for quality (or if I'm going to send it to a professional printer). For the rest of it - read and inwardly digest all the information in your printer handbook. It
really is worthwhile. Learn about 'smoothing' for black and white images.
REMEMBER
This is NOT the definitive guide to scanning. It is a summary only of what I have found to be good sound advice. PLEASE visit the sources given above for a more in-depth study of this subject.
