By Simon Firth, July 2008
A glossy, beautifully produced book of photographs used to be something only publishing pros could dream of making.
Today anyone can custom-create a high-quality photo book from a personal set of digital images and print it at a reasonable price. Yet the ability to print a personalized photo book brings its own set of problems: The images themselves.
Fancy photo books used to contain professionally shot images. Pictures shot by the rest of us don’t tend to look as good.
“Even when we’re good photographers, it may be that the image that means the most to us emotionally has some flaw,” says HP Labs researcher Carl Staelin. “Maybe the camera's exposure was wrong, or the person was moving, so it's a little bit blurry. But that’s the one you want to print.”
Now Staelin and fellow researchers at HP Labs in Haifa, Israel have a solution – a one-stop process that automatically improves any picture – that is now available as an enhancement to HP Indigo 5000 and 5500 digital presses. Although the technology is particularly useful for photo books, it can be used on to improve any image.
Want to try it for yourself? The auto-enhancement software is available at Snapfish Lab, a site that houses experimental photo tools from HP Labs. You can see samples of how the tool works, or you can upload your own images (free membership required).
The researchers' solution, known as the HP Indigo Photo Enhancement Server version 2.0, uses seven proprietary algorithms to analyze each photo entering the press and determine exactly which enhancements, and how much of each one, a particular image needs.
In one pass, it can sharpen a picture, improve its contrast (through adaptive lighting, brightening/darkening, contrast stretching and 3D boosting), and reduce the ‘noise’ and artifacts in the picture caused by digital compression.
The process is designed to run incredibly fast. An HP Indigo press can print an A3 sheet of color photos (297 x 420 mm or 11.7 x 16.5 inches) every second or so. During peak printing seasons (such as the run-up to Christmas) commercial print shops might have 20 such printers running in parallel, 24/7 for weeks at a time – and each needs to be capable of printing a different auto-enhanced image on every single pass.
Certainly, it’s important that the technology make every picture as good as it can be. But equally crucial, says researcher Renato Keshet, “is that it doesn’t make it worse. We need to either make the image better or just leave it the way it is so that no human intervention is needed.”
The research that led to the automated photo-enhancement technology began almost as soon as Indigo was purchased by HP in 2002.
“We’d already started to see content from amateur photographers being printed on Indigo presses, particularly from applications like online photo albums,” recalls Shlomo Harush, manger of Indigo’s Color and Algorithm research group.
That inspired Harush and Indigo Chief Technology Officer Pinni Permutter to ask their new colleagues at HP Labs Israel to help Indigo apply existing HP image-enhancement technologies to the Indigo process. In 2006 the two groups decided to bundle those technologies into a single platform – and within two months the Labs researchers had delivered the prototype.
To create the prototype, the team – which also included researchers from HP Labs in the U.S. and UK, as well as from HP's Imaging and Printing Group – scoured HP for the best image-enhancement tools they could find.
What they couldn’t find, they made themselves. For example, researchers found that sharpened images looked fine – except when it came to people's faces. So they developed a "map" for human skin, which let them reduce the amount of sharpening on skin pixels. That skin-mapping technology came in handy for a variety of functions.
Indigo customers have been using Version 1.0 of the technology successfully for more than 18 months. Version 2.0 includes skin-tone correction, an automatic makeup feature and red-eye reduction options.
It “gives us is a huge advantage relative to our competitors,” says Indigo’s Harush.