BitDepth 587 - July 31

Planning on creating a 2000 gigapixel image? There's now a format for you.
Truly big pictures

A close-up of a medical slide (top) and a detail of Andrea Pozzo's 1694 fresco displayed using Adobe's Zoomify technology. 

How big is a really big photo? If you're thinking in megabytes or megapixels, well the world became a much bigger place recently, as technology developments drove the adoption of a file format capable of supporting gigapixel and terapixel file sizes.
Whenever the topic of capacity and file sizes becomes news, I'm always reminded of that infamous quotation attributed to Bill Gates, "640kb should be enough for anybody" which referred to the memory allocation that personal computers on the IBM platform started off with. Check the system properties or system information on your own computer and have a little giggle over that one.
If there's any absolute I've learned over the decade that I've been writing this column, it's that the unimaginable is only waiting for the right mind to imagine it.

Big picture limits
A few years ago I was stitching a big panorama together from scanned medium format images when I hit the pixel limit of Photoshop, which was, at the time, 30,000 pixels on each dimension. Since then, Adobe has introduced a "big" Photoshop format (PSB) designed to make it possible to work with larger image files, but there have been limits to writing a file larger than 4GB even with the new format.
Two recent projects defeated even Adobe's PSB file format and demanded a whole new format, Big TIFF, developed by in collaboration by two companies Aware Systems and Aware Technologies.

The new format for TIFF files gets around a register problem that's been an issue with computers since they began making their way onto the desktop of ordinary folks.
Computer processors first handled eight bits; then 16 and today's systems work with 32 bits quite comfortably. Understanding the way that computers handle bits across a memory register is way beyond the kind of stuff that we usually get up to on this page, so think of it this way. 
If you imagine a computer as an old Chinese abacus, and each extra bit as an extra abacus added to the working capacity of a lightning fast, furiously calculating market vendor during the Han Dynasty, then the computing capacity grows exponentially as those bits double.

64 bit Magic
Computing using 64-bits remains out of the mainstream, but it's the next horizon and there are versions of the Mac OS and Windows Vista and specialised scientific software that can make use of processors capable of working with 64-bit registers, although most of the software you and I can buy is still to make the jump.
That impressively confusing digression is supposed to set the stage for the magic that Aware Systems and Aperio Technologies have managed to create with this file format, which uses 64 bit registers to allow these massive images to be readable. 

Since nobody has the time to download a multi-gigabyte file, these images are available on the Internet for viewing using Adobe's new Zoomify technology, a Flash based viewer that's a feature of the newest version of the software.
The Zoomify interface acts like a digital keyhole to the image, as you click to zoom in, the software pulls the pixels for just the section of the picture you want to see details of.

Big displays on the web
The most interesting file is a digital reproduction of La Gloria di Sant Ignazio, a reproduction of a fresco painted in 1694 at Loyola's Church in Rome. The final image is a 9.9 GB file and is created from 1,188 individual images stitched together. 
The clear leader in the picture size sweepstakes is a medical scan of a breast cancer slide, combined rather redundantly 225 times to create a terapixel image that's 2,876GB in size. This image is really a proof of concept, since most medical professionals can manage just fine with one image for study, but it opens the door for some interesting times ahead.

The BigTIFF format has been placed in the public domain and Aperio Technologies is, according to a press release "working with the TIFF standards body to incorporate them into a future standard release."
Expect a BigTIFF plug-in from Adobe for Photoshop eventually, but all these advances really beg the question, what do you do with a file that size that's really useful?
Which is really my entry in the quotable silly technology question of the future competition.

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