Sensor and sensibility

Sensor and sensibility
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First Published: Wed, Apr 29 2009. 12 56 AM IST

Updated: Wed, Apr 29 2009. 11 27 AM IST
I’ve been giving a number of lectures and slideshows recently and each time, without fail, there comes a moment when somebody asks the $6 million (Rs30 crore) question of modern photography: “My camera has 8 megapixels—is that enough?”
Being hung up on measurements is nothing new but in their bid to steal a march on the competition and keep mining money from customers’ pockets, the camera industry is in danger of turning photography into one big ‘who’s-got-the-biggest-equipment’ contest. The fact is that most people shopping for a camera will rarely print anything much bigger than standard photo album size. The camera on your mobile can probably manage this, so buying a state-of-the-art multi-megapixel camera is equivalent to buying a Mercedes C-Class and using it to drop the children to school.
Nevertheless, just as you sometimes need to howl down an autobahn at 200 kmph, you may at times want to print pictures bigger than the capacity of your sensor. The good news is that you needn’t rush out and drop half a lakh on a shiny new image box. You can short-circuit the megapixel race with a selection of software tricks.
Intelligent uprezzing
The target resolution for good printing is 300 pixels per inch (that’s 118.11 per cm, metric heads). If you want to make an 8x10 inch print, you need to feed your printer a file that’s 2400x3000 pixels—7.2 megapixels. If your source image is much smaller than this, your print will come out looking like a splendid Roman mosaic of overblown pixels.
Uprezzing or upsampling is shorthand for the process of increasing image size and resolution using software. Without delving too far into the geeky details, this is done by packing new pixels of similar colour and tone into the non-existent spaces between the ones that are already there. It’s the electronic equivalent of boarding a Mumbai local train during rush hour. Almost any image-editing programme offers this facility, but some do it better than others. Here are some that I use regularly:
Upscaling in Photoshop
Packaged free with many digicams, Adobe’s Photoshop Elements offers quick and clean image expansion through the Image Size command. Tick “Resample image”, punch in the pixel dimensions you want, set the sampling method to Bicubic and watch it go. Similar facilities are available in free photo-editing software such as Gimp and Irfanview.
Tip: Upsampling in 10% increments gives a smoother, more convincing result.
Adobe Camera Raw (ACR)
If you’re shooting RAW files and editing in Photoshop, you can choose to upsample at the time of conversion to an editable TIFF file. Even if your camera captures a relatively lowly 8.1 megapixel file, ACR can open it at anything from 1,526x1,024 pixels (1.6MP) to 6144x4096 (25.5MP). However, this method can produce somewhat wild and woolly results, and works better in small doses.
Genuine Fractals
When you seriously need to put your pics on steroids, this is the boy. It operates as a plug-in to Photoshop, Lightroom and Apple’s Aperture, and can comfortably increase an image by 400%: I’ve used it to convert an 8.1MP capture into a wall-filling 40-inch canvas. You can download a 30-day free trial version (a daunting 250MB file) at www.ononesoftware.com.
All uprezzing involves guesswork by a machine and there’s no doubt that the more raw data you can capture, the more potential you have to make good large prints. But the message is, don’t get hung up worrying that your equipment’s inadequate. You can always make it look bigger on Photoshop.
David Stott is a photographer based in Australia. Write to us at sharpshooter@livemint.com
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First Published: Wed, Apr 29 2009. 12 56 AM IST