Buying Guide: 6 best photo editors and organisers for OS X

You might think image editors such as Photoshop are the be-all and end-all of digital photography. But the more photos you take, the more the issue of organisation rears its head.
You can file away a small amount of photos in named folders and be reasonably sure of being able to find them again. But when you run into thousands, filing problems take on a new dimension. This has led to a new type of all-in-one photo cataloguing and editing app, with iPhoto at one end of the spectrum and Aperture at the other.
They also offer 'non-destructive' enhancements where the original photo is left untouched, and any adjustments are stored within the program's photo database instead.
Picasa takes the same approach, while Lightroom is an 'alternative Photoshop' for photographers who need organising tools first and image-editing second. But you've still got classic image-editing apps like Photoshop and Elements, which are bundled with their own separate photo management programs.
So which one of these is best? We've approached the problem from the point of view of amateur photographers looking for a combination of organising and editing tools, ease of use and value for money. And we think we've found a worthwhile winner…
Apps on test
Adobe Photoshop Elements 9 - £67
Adobe Photoshop CS5 - £658
Adobe Photoshop Lightroom 3.3 - £238
Apple iPhoto '11 - Free/£9
Apple Aperture 3.1 - £173
Google Picasa 3.8 - Free
Test one: Picture management

Photoshop comes with Adobe Bridge, which has hidden depths. It can sort and filter photos according to keywords or metadata, and organise them into Collections. It can even stack related photos.
Picasa is also a file browser, but while its professional appeal is limited, it's extremely good at fast keyword searches and can display your whole photo collection in a single window. But neither can really keep up with the others.
We all know iPhoto, which is fast, simple and effective, but it doesn't offer stacking tools, and stores your photos in an internal filing system.
The new Photoshop Elements Organizer is much better in that it works with your existing filing system and offers more transparent control.
Top dogs, though, are Lightroom and Aperture. Lightroom is the easiest step up from an ordinary browser like Adobe Bridge since it shows your photos' folder locations, but Aperture can't be beaten for its speed, flexibility and interface.

Test two: Photo editing

The photo editing tools in iPhoto are effective at everyday image fixes, and you can have some fun with the Effects, but that's about all.
Picasa looks equally simplistic, but you can actually do just a little more with your photos, thanks to things like the graduated tint and filtered black and white effects. Both use 'non-destructive' editing, where your changes are stored by the software rather than applied permanently to your photos.
That's the approach taken by Lightroom and Aperture, too, but since these are professional apps it's no surprise to discover their editing tools are far ahead of iPhoto's and Picasa's.
Aperture is terrific, but Lightroom has the edge, with new lens correction profiles and easy-to-use adjustment presets. But if you need layers, filters and other fullon image manipulation tools, you need an image-editor.
Elements is a lot closer to Photoshop than people imagine, especially version 9, but Photoshop is still top dog.

Test three: Ease of use

This category is harder to judge because these programs all have flaws.
iPhoto is the simplest, but little things can still trip you up (where exactly has it put your photos?). And despite being revised in the latest version, its geotagging/mapping tools are still hard to fathom.
Picasa's problem is that it's a cross-platform app that uses an effective but odd folder display and management system quite unlike what Mac users will be accustomed to.
Photoshop is, as you'd expect, very technical from the start, and while Elements is a lot better, it tries a bit too hard to help you - sheer choice becomes confusing.
Aperture and Lightroom are professional apps, so you're dropped in at the deep end. But it doesn't take too long to figure out the basics. Aperture is the one with the most longterm flexibility, but you'll figure out Lightroom quickest, since it's not too big a step up from a file browser like Adobe Bridge, and the tools are less daunting.

Test four: Value for money
Picasa looks like it's the best value for money since it's free, but then you could say the same for iPhoto, which is paid-for only if you upgrade from an older version.
At the opposite end of the scale you've got the hugely expensive Photoshop, which doesn't do a whole lot more than Elements, at least as far as photography is concerned. In fact, given that the Organizer app supplied with Elements is actually more effective at organising photos than Adobe Bridge, Elements looks better still.
But let's not rule out Aperture and Lightroom. Neither is cheap, but both are highly capable apps designed for pro photographers. Of the two, though, Aperture is the best value because it's significantly cheaper.
In the end, though, we'll go for Elements. iPhoto and Picasa might cost nothing, but they lack depth and and you could soon outgrow them. Photoshop, Aperture and Lightroom deliver diminishing returns for amateur snappers.

The winner: Photoshop Elements 9

We were looking for the application that delivered the best all-round combination of photo organising and editing tools, ease of use and value for money, and the program that ticks all the boxes is Photoshop Elements 9.
It offers a large proportion of Photoshop's image-editing tools at a fraction of the price, and the new Organiser app is powerful and simple. Its one disadvantage is its old-school approach-switching between two separate apps for the editing and organising functions.
If this gets your goat, look at iPhoto and Picasa. They cater well for the beginner, but don't offer enough for enthusiasts, while Aperture and Lightroom cater very effectively for professional needs.