Harriet Walker: It's an easy way to put some glamour back into our lives

When lumps and squidgy bits are shaved off celebrities, things become significant

Since Oliver Cromwell was the first public figure to be painted with 'warts and all', we've been obsessed with the veracity of images presented to us. And why not? The urge to see stars at their most slovenly is entirely natural, given the completely human need to discover our betters' feet of clay.

But this is precisely the point of Photoshopping – not to keep us in our place by making the rich and famous look better than they do but to maintain some illusion as to the more glamorous things in life. The deep-seated need to see spotty celebrities buying milk is double-edged: we also want to to see them looking as coiffed and primped as is super-humanly possible.

Every so often, there is a magazine cover or ad campaign unveiled which is decried for having rendered its subject almost unrecognisable. Some victims to date have been Gwyneth Paltrow, whose head once jutted from her neck at an entirely unnatural angle on a US Vogue cover, and singer Beyonce, whose skin was noticeably lightened in a make-up commercial.

These goofs are regularly pointed out and sneered at; it's when lumps, bumps and squidgy bits are shaved off our celebrities midriffs and thighs that things become significant. Grazia had to apologise last year for winnowing Kate Middleton's waist. They explained it was because they'd had to replicate and flip her left arm to create a picture of her without Prince William. The result was ectomorphic in the extreme. In these cases, perhaps a rating system would work. But for the most part, bad Photoshopping is as obviously unreal as the birdlike proportions it produces. And young consumers are increasingly aware of its limitations.

The best Photoshopping enhances an image in the same way as Leonardo's chiaroscuro, however, and to rate every single photograph would rather seem to detract from the aesthetics involved.