Procedure for Scanning Documents
Wherever possible, documents are scanned at 100 percent of their original size (i.e. 1:1) at 600 ppi resolution and using 24-bit color (i.e. 8-bit RGB color). Each document is imaged together with a small Kodak Q-13 color separation guide and ruler. The master scans are saved as uncompressed TIFF files (which generally range in size from 70MB to 130MB). Images of documents owned by the Natural history Museum will be archived on its DAMS system.
Images for Web delivery are edited and then cropped to remove the colour separation guide. They are then converted to 300 ppi and resized if neccessary so that their longest side is about 2000 pixels. They are then sharpened and watermarked as appropriate. The final images are saved as jpgs, usually at the highest quality setting. The file size of these images varies, but generally they are around 2MB.
In the case of letters, blank intervening pages and trailing blank pages are not scanned. For example: If a three-page letter has writing on page 1 and page 2, but not on 3, then only pages 1 and 2 are scanned. If, however, it has writing on pages 1 and 3 then blank page 2 would not be scanned. In the case of other documents such as notebooks, ALL pages are scanned
All items which were part of the letter (more precisely the 'letter packet') when it was posted are also scanned or photographed e.g. original envelopes, enclosures etc.