Collectible Stocks and Bonds from North American Railroads     by Terry Cox

A guidebook and catalog of prices
(I do NOT buy or sell certificates on this website)

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Scanning certificates

Scanning as "art"

I receive numerous inquiries about how to scan certificates. Having scanned countless certificates, tens of thousands of maps and millions of pages, I have to tell you, scanning is often more art than science.

To most people, scanning is a dark science. Like most endeavors, however, the more you know, the less mysterious it becomes. Yes, there is a certain art involved, but I think a large chunk of art is knowing what you want and knowing ways of getting there. Scanning demands experimentation. If you are going to scan certificates and want good results, then experiment.

How this information is arranged

I've divided my discussions of certificate scanning into small pieces. Click any of these sections and you will find "rabbit tracks" of discussion that will weave back and forth across the subject of scanning. Read as much or as little as you want. Come back to this page when you want to learn more. Beginners: please read Quick Scan Hints.

Scanning advice

Autoexposure Manual exposure. Auto-exposure makes it easy to get adequate scans as soon as you plug in your new scanner. But that doesn't mean you can't get better results by turning auto-exposure off.
Autoexposure Autoexposure: This link will show you results you will get when when scanning certificates with with different thicknesses.
Brightness Brightness. Between 25% and 50% of the images of certificates you see in online auctions are dark. Let's look at the reasons.
Color Color. Many people wonder, "Why are my scanned images different colors than my certificates?"
Contrast Contrast. Contrast is the differerence between light and dark areas. You can control the attractiveness of your scans by adjusting contrast. It can make a world of difference.
Formats File formats. I will explain the differences, uses, and sizes of JPGs, BMPs, GIFs, and TIFs.
Formats Effects of JPG compression from too many saves. Learn why it is a bad idea to save JPG images multiple times.
Formats JPG compression. Unlike other formats, you can control image sizes with JPG compression. JPGs let you save information in smaller files than any other format. Learn why compression is not a bad thing.
Hints Quick scanning hints. For collectors who want to get started with a minimum of knowledge.
Large certificates Large certificates. Tricks to use when your certificates are larger than your scanner.
Purchase Purchasing a scanner. Entry level, letter size scanners can be had for under $100. Scanners capable of scanning 11x17 sheets are now available for under $250. I offer a few hints on buying.
Sharpening A little sharpening is great for ordinary typed pages. It is usually NOT great for engraved vignettes.
Reduction Reduction during scanning. DON'T do it! Beginners often send images that were reduced during the scan process. They didn't know that their scanner was set up that way from the factory. I show an example of unintended results.
Resolution Resolution. Beginners always scan at higher resolutions than they really need. Unless you are publishing is a slick magazine, you rarely need anything over 300 dpi. (A 600 dpi image requires four (!) times the storage space of a 300 dpi image.) Here, I show you several real-life examples of different certificate resolutions and I explain the math.
Sending images How to send images. I always need images from collectors. How you can send scans or photocopies.
Sending images Why didn't I use images you sent? I don't use all images that collectors send, usually because of common problems.
Terminology Pixels, dots, and samples. Professionals argue incessantly about the proper terminology to use when talking about imaging. Scanners collect samples, monitors display pixels and printers print dots. There is no agreement on terminology. I say, "Ignore the confusion." Use any term you want. Dots are every bit as good as pixels. Only the pros discuss samples.
Terminology Understanding bits. In geek-speak, grayscale images are '8-bit images' and color images are usually '24-bit images.' At some point, you might enjoy understanding the meaning.
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(Last updated November 15, 2016)


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