Each issue, Cool Kit takes a look at kit - equipment and tools - available to photojournalists for their work. Here we examine image resizing and what is needed to achieve it.
When you take a photograph on a digital camera, its quality when printed depends on a number of factors. Among them are the type of camera you are using and the dimensions of its sensor together with how good your lens is. Then there is the level of compression you employ and the resolution you shoot at.
Many digital cameras give you choice over compression though a decreasing number still offer just 8-bit JPEG, explained in detail from a link at the foot of the article and in this edition's Ask The Experts feature.
More expensive models now offer capture in 16-bit RAW, which records exactly and only what is seen through the lens - uncompressed - for the highest quality and greater flexibility in post-production.
However, what all cameras have is a maximum possible resolution which can prove insufficient for displaying and selling your images, particularly to magazines requiring high-quality photographs.
You will almost certainly have to resize your picture upwards – “blow it up”.
If, for instance, you want to sell a picture to a magazine or leading agency, many will require the file to be at least 50 Mb in size. Which means you will need to increase the size of the original by several times whilst being very careful not to damage its quality unduly.
You may also have to reduce it for other uses: 5 Mb, produced by even the most basic cameras on sale now, is too big for a web page or an email – even in these days of broadband.
First downsizing. This is the easier of the two because you are taking an image with a certain number of pixels and making it smaller, so there should be little loss of quality.
You will almost certainly lose sharpness but there are ways to solve this, particularly in Photoshop CS and CS2, the latest version of the leading professional photo editing software which offers tools for resizing which are effective and relatively easy to use.
There’s a link to an article detailing what to do at the foot of this article.
But Photoshop is expensive and there are many other alternative programs which also offer tools for resizing downwards or are dedicated to the task, and some are free.
And there are websites which actually do the job online, such as resize2mail.com. This can be useful if your are working on a machine away from home, such as in an internet cafe.
Upsizing is more challenging because once a picture is taken, you can not add more information of the original subject so blowing the picture up, without help, inevitably reduces quality. The same number of pixels occupies a bigger area and resolution, by definition, decreases.
What many software packages do is analyse pixels and add new ones as closely-related as possible - part of the process known as interpolation. They do so in different ways.
Many experts say Photoshop does a good job. But others reckon there is a limit to its effectiveness, arguing that blowing up a 5 Mb image by 10 times, for instance, will not look as good as it should.
There are specialist packages which some professionals claim does the job better. Two of these are Genuine Fractals and Smartscale, both plug-ins for Photoshop which were originally owned by two separate companies but have both now been acquired by Onone Software.
Both use different software techniques to Photoshop to replicate pixels. There’s a link to a pdf document explaining how Genuine Fractals works at the end of this article. And there are links there to reviews of both.
There are a number of programs which offer different solutions and links to some appear below. Blow Up from plug-in specialists Alien Skin is one. Photoresizer Pro and PhotoZoom Pro 2 are two more.
But, as always, do plenty of research and check out free trial downloads from those companies that offer them.
Happy resizing.
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