Compression and Progressive Transmission of Digital Images

We are developing a client/server system that allows users to browse and download digital images over very low bandwidth connections such as telephone dialups. These connections can be as slow as 2400 baud, and we can, for example, deliver a lossy 800x800 16-bit image that is visually indistinguishable from the original in about a minute.

Highlights of FY95


Our original proposed milestones were rearranged, after consultation with the DLT Project, to provide a quicker delivery of a prototype system. We had originally planned to do a classic linear development, culminating in a working system at the end of the second year. We decided to go with the "rapid prototyping" model instead, get a product out a year earlier, and then go back with beta test reviews and improve the system iteratively. This has worked very nicely, the product is already in the field, and preliminary reviews have already been received.

The table below reflects the revised milestones.

Milestone Date Met?
Deliver non-GUI testbed to DLT project 01 Mar 1995
Upgrade protocol for interactive use 01 Jun 1995
Implement Tk-based client GUI 01 Jun 1995
Implement simple, portable X-based viewer 01 Jun 1995
Deliver end-to-end system to DLT, RSPAC 25 Jul 1995
Convert source code to ANSI standard C 01 Sep 1995
Server preprocessors 01 Oct 1996 -
Provide improved GUI client 01 Oct 1996 -
End of user evaluation period 01 Apr 1997 -
Final release 01 Oct 1997 -


The first year of our project saw the upgrade of the testbed Progressive Image Transmission (PIT) software from a simple command-line, non-GUI, non-imaging, and non-interactive proof-of-concept to a fully functional, GUI-based X-windows system capable of supporting casual and professional users of digital image libraries.

Our revision of milestones resulted in accelerated deliveries of all major components of the proposed system: