Scanning Guidelines
Parabaik Manuscripts
Scanning Guidelines
It is recommended that a single scan be done from which all derivatives can be produced.
Benchmarking
The calculations predicted that:
for a bitonal (1-bit) image with a resolution of QI = 5, we had to scan at 128 dpi, which can lead to file sizes of 0.16 MB.
for greyscale (8 bit) image,with a resolution of QI = 5, we had to scan at 64 dpi, which can lead to file sizes of 0.32 MB.
However, from the start, we knew that we wanted full color (24-bit) scanning for parabaiks so we could capture the artifactual value of the manuscript. Initial scanning revealed that at 8-bit that there was dithering and we not capturing the full color range of the manuscript. Using the above calculations and initial scans we did scanning samples in 24-bit, 100 dpi, 200 dpi and 300 dpi.
The following are actual size of images scanned at different resolutions.
24-bit, 100 dpi.
24-bit, 200 dpi.
24-bit, 300 dpi.
Here are samples of scanned images that have been converted to JPG from TIFF for browser display. The following are full image samples of 24-bit and 100 dpi (202 KB); and 200 dpi (654 KB); and 300 dpi (876 KB). Press Back of your browser after viewing the file.
Our Recommendation: Parabaik
Scanner settings should be 24-bit, 200 dpi.
expected file sizes: 9.6 MB files. LZW compression can reduce this significantly. Recommended file format for master images is TIFF with lossless compression.
At 200 dpi, we can get 1.6 pixels straddling over the finest stroke in the collection, which gives a pretty good image.
At 150 dpi, we can get 1.2 pixels straddling over the finest stroke in the collection, which gives a good image.
Scanner choice
A flatbed-scanner capable of scanning 17 inches would be a good choice. Take note that the flexibility of the manuscript may not allow the manuscript to lie flat on the scanner.
It is possible to use an 8" x 11" or 17" scanner for materials longer than 17 inches. But this may not be acceptable in a production environment. Scanning will have to be done in parts at a time. Another scan will have to be made to scan the remaining part. A graphic software can then be used to join the two parts and have a single image that can be scrolled left or right.
A digital camera with a resolution of 3450 x 1050 pixels and 24-bit color would be a good choice for materials up to 23 inches.
Image Enhancement
Image enhancements can be done to the derivatives for better printing and screen display of materials. Brightness and contrast, threshold adjustments can be used for better derivative images.
File format: TIFF
Sticking to a widely accepted file format will make migration later a lot easier.
Compression: LZW (lossless)
LZW is a well-documented file compression algorithm that can be implemented by any decent computer programmer.
Storage Media: CD-ROM
This media does not require additional special handling and storage. Although it has not been proven yet that the information on a CD-ROM can be erased through time, it is a nice idea to check the readability of cd-rom at periodic time intervals.
Having backup copies in different sites increases the chances of recovery.
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