Complex Photoshop selections

Venerable warhorses

One of the trickiest - and most frequent - Photoshop tasks I and other web designers face is making complex selections: the 'isolation' or 'cutting out' of a part of an image for use in a collage or overlay on another background.

It's a bread and butter graphic design trick that, when done right, is always effective, adding a sense of depth, a three dimensional element, to a flat surface. You see it all the time on newspaper mastheads and magazine covers, and on packaging. It can look good on websites too: I've used it quite a bit over the years, usually to add visual interest to a masthead.

If the subject has straight or regular curves, like a building, it's quite straightforward to trace the shape. But more often than the requirement is to cut out the irregular outline of a person, with the random folding of clothing, the contour of faces, and, most challenging of all, strands of hair. Even then it's not too difficult if the person is photographed against a solid background, such as a white wall or a blue sky. Often though they are pictured in front of complex, busy backgrounds, with light and dark areas, and multiple colours.

That's what I spent much of last week doing: trying to extricate pictures of pupils and teachers from chaotic backgrounds for a set of masthead banners for a school website. Trying to turn something like this -

The kind of image that needs to be isolated

- into something like this:

The cutout in use on a masthead

To cut a long story abruptly short, successful selection involves plenty of masks, channels, use of the pen tool and the overlay brush:

Selections made using layer masks

A close up of a selection on a duplicated channel

This kind of complex selection is discussed in most Photoshop books, and there are quite a few good online tutorials (like this one - Photoshop Complex Selection Tricks). But the discussion is usually rather cursory, usually with a simpler case study than the designer has to deal with in real day-to-day work. Fortunately there are two books I've been able to turn to every time I'm struggling with this, both of them quite a few years old now, but still just as useful as they ever were and which I'm plugging quite unashameably here.

The first is The Photoshop Channels Book by Scott Kelby. I don't even know if it's still in print, but the opening chapters offer a series of excellent case studies on how to use red, green and blue channels as starting points for picking out subjects against similarly coloured backgrounds, even the nightmare scenario of fine dark hair strands against a near black background.

That book was published way back in - gasp - 2006, and it is still one of the most valuable I own. But the second, which is even older - 2005 - is surely still the definitive work on the subject, and I think one of the best two or three Photoshop books ever published (and I have quite a few): Photoshop Masking and Compositing by Katrin Eismann. This exhaustive tome has nearly 500 pages dealing with every conceivable aspect of complex Photoshop masking and selection. There are lengthy, forensic chapters providing step-by-step instructions on how to select every kind of object against all possible backgrounds: light on dark, dark on light, regular shape against solid background, irregular shape against busy background, flyaway hair against solid backgrounds, flyaway hair against complicated backgrounds - and so on and on.

It's expensive, and you might need to get it second hand, but emphatically worth it. One of the chapters is available online as a sampler Selecting Hair and Fine Detail in Photoshop, which gives a good sense of the kind of awkward real world situation the book deals with.

To be fair there's another book of similar vintage that I haven't yet read, Nigel French's Adobe Photoshop Unmasked: The Art and Science of Selections, Layers, and Paths. And there's the more recent Photoshop Compositing Secrets by Matt Kloskowski, which is edging towards the top of my Amazon wishlist.

I'd be (pleasantly) surprised if they matched up to Eismann's classic though, which I don't often see referenced, and which deserves trumpeting at every opportunity: it had the answer to every selection problem I encountered last week, as it has always done in the past.