Summary:
These Guidelines indicate recommended requirements for web-deliverable JPEG image files derived from master TIFF image files created for PALMM projects.

Specifications:

File Format:	JPEG (Joint Photographic Expert Group) Specification: ISO 10918-1/2 Reference: http://www.jpeg.org/public/jpeghomepage.htm
Encoding:	Standard
Compression:	Minimum (highest image quality), Not greater than 15% (image quality not less than 85% of source file)
Bit-depth:	Same as source file
DPI:	Same as source file Mitigation of scaling may require down-sampling or Gaussian blur.  These processes require skill and experience.
Image Dimensions:	Width = 630 pixels; Height = variable Maintain original image aspect ratio Note: PALMM currently provides an area 630 pixels wide for document image display.  Wider images will scroll horizontally.  Horizontal scroll, generally, should be avoided for documents with portrait orientation
Interpolation:	Resample
File Header:	Append structured information about the derivation process as appropriate to the SUSDL XML Metadata DTD (forthcoming) A structured information template will be added in a future revision of these Guidelines

Process:
No single method of processing is recommended.  However, whether converting images individually or by batch process, a visual inspection together with a query of the file header should be completed by spot check.  Spot check requires inspection of every image in thumbnail view and of no less than 10% of the images in full-image view.
A variety of factors effecting on-screen and print legibility should be examined.  For additional guidance, we  recommend reading Cornell University's Digital Imaging Tutorial: Quality Control.