Post-Digitisation Processing

Post-processing (QC) is mainly covered in the previous section. If there was not enough time to perform Quality Control on the images as we were scanning, this would be done now.

Please visit the samples page to view the final images, as well as images of other work we have done.

Derivative Creation using Batch Scripting

We found Adobe Photoshop's Batch Scripting to be an effective way to create derivatives. A Batch script is created that will open a master image, resize it and apply a small amount of Unsharp Masking (usually 45%, 2 pixel radius, 2 level threshold) to it, and then save it into a new directory on the computer as a jpeg image of varying quality. Extra Unsharp masking is used because any change in resolution will cause a softening of the image.

We also use Batch Scripts to add Metadata comments to the TIFF image files using EXIFUtils software.

Please refer to the National Digital Forum's website for further information on image file format and Metadata standards.

Please refer to the Western States Digital Standards Group Digital Imaging Best Practices. For more information on these guidelines, a pdf file is downloadable from here.

Writing Data for Clients/Output media

Due to the large file sizes involved for the master images we currently recommend the use of DVD's as transfer media to client. We currently write Masters to Delkin Archival Gold DVD-Rs. The derivatives are written to separate CD-R media. We write using either Easy-CD Creator Professional  and Nero under Windows and Toast Titanium under MacOsX.

Although the CD-writing can be performed at high speeds there is a great deal of discussion currently about higher speeds encouraging high BLER (block-error-rate) on CD's so we currently believe it is better to write at a slower speed (<8X) in order to achieve the best result. DVD's are written at 2X speed. Our CD's are currently packaged in a slim-line jewel case with a laser-printed label printed on acid-free paper and written on with pencil. No sticky labels are affixed to the CD/DVD. We write an index number on the clear centre part of the CD/DVD.

We are looking into the possibility of using the DVD-type black cases which allow for a slick to be placed on the outside of the case. This may have benefits but we have yet to determine this.

For this job we elected to use DVD's for the master images and CD's for the derivatives.

The Master images took up six DVDs (29,000MB), and the derivatives took up 4 CD's (2,900MB). On each DVD or CD was written the client and job information, the image format, and the images on disk, as well as the disk number.

We recommend that the client takes the transfer and imports the files into their IT infrastructure for ongoing storage, management and migration. The optical media might be stored in controlled conditions, as an additional backup but we do not recommend it as a preservation medium.

We retained the images on our system for 3-6 months to give the client time to check them.