Image Display Manager

Note: Four images totalling 265 kbytes are displayed in-line on this page.

We are dealing with a large collection of scanned railway map images (or perhaps more accurately the real estate in the vicinity of railway lines). With TIFF in-built compression, these colour images are typically 32.1 MB in size, each. About 20 at most can fit on one CD. We crop them marginally (using the top "dead" area) to provide images of dimensions 4000 x 2664. From 32.1 MB, the compressed image is typically 0.62 MB, implying that we have shrunk the image file to 1.9% of its original size. Even allowing for various overheads such as image icons and textual annotations - clearly taking up very little space - and two versions of the compressed data to support two different block regions of interest - notwithstanding this we can easily envisage 20 times the amount of information on one CD.

We can support 400 images on a CD with this image management system, compared to the erstwhile 20. For delivery of image regions of interest over the web, this system is evidently of importance: the decompression is done on the server, but a limited and controlled rate of data is transmitted for display to the user. Imagine 32 MB of data to be transferred on today's Internet!

The first screen shows a large number of clickable image icons arrayed on the left. This is the image collection supported. Putting the cursor on an image, without clicking, brings up a textual annotation, shown in subsequent images below.

We select image 12. The title bar and lower left provide textual annotation. A low resolution version of the image pops up in a new windows. Decompression to this resolution is on the fly. Clicking on this image will provide region blocks of interest. Depending on the high/low resolution toggle button in the title bar, two different levels of resolution are supported.

Using the "knot" on the railway line towards the upper left, we look at a low resolution and a high resolution view.

Instead of using the image icon in the separate, draggable window, an alternative navigation mechanism is provided by the arrow keys. For given resolution in effect - high, low - these allow neighbouring region blocks to be visited and displayed.

Images displayed - at high or at low resolution - can be saved. They can be uploaded later to a portable and mobile display platform (e.g. a Sony Vaio C1, or even a Compaq iPaq).

Acknowledgement: Images from Digital Archiving Services N.I. Ltd., Belfast.