Tuesday, January 23, 2007

Very Large Images on your disk

While there are quite many images you can view on the Web (see previous post), there are actually very few you can download to your machine.

You can find few on my VLIV viewer page, and instructions to create the NASA Blue Marble Next Generation from NASA dataset

As most technologies to provide Web viewing are HTTP based, it is quite easy to use a mass downloader to download individual tiles just like the Web viewing techonogy does. Rejoining them to recreate the full image is easy then. Because of copyrights and intellectual property, I will not disclose how to do, but so far I have successfully recreated images originating from the Google Maps API (easy) and Zoomify (harder), even multiple Gigapixel ones.

The most common format for tiles is JPEG, and the largest image I have is about 360x350 tiles of 256x256 pixels.

Needless to say, viewing very large images stored on a local disk is impressive, because of the speed compared to Web viewing. There is no delay when panning and zooming.

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