But Digby-Jones says his true retouching training began when he first joined S&B as a Barco Creator operator. (Creator was one of the most powerful image-manipulation programs of the 1990s and was aimed at the repro and print-shop markets.)

“I learned the finer disciplines of image compositing and photographic retouching, and these skills were transferred back over to Photoshop, as it became more powerful and able to handle the multilayered files that we were working on,” he explains.

One of S&B’s specialities is stylized photo-realistic CG images for the automotive industry, a process in which Photoshop has a key role to play. For an in-depth look at how a Saddington & Baynes car ad was composited, see Digital Arts, December 2008.

“We have a whole CG department creating imagery that is composited and graded in Photoshop, along with other creative applications such as Corel Painter, and Apple Shake,” says Digby-Jones.

“One of Photoshop’s most powerful elements for me,” he says, “is blending modes. This gives the ability to control subtly different aspects of light and colour through adjustment layers on certain blending modes, or to combine the qualities of different image layers, thus simulating what happens naturally in photography with multiple exposures, and all the time in a nondestructive way.”

It pains Digby-Jones to see sloppy Photoshop work. “The things that stand out most for me are examples [of composites] that contradict the natural behaviour of light, and how a scene is captured through a lens.”

He adds: “Examples would be mask edges whose sharpness don’t match the focus of the object they mask, mismatched black densities and colour temperature of composited elements, and mismatched perspectives.”

Over the years, Digby-Jones has mastered enough techniques to fill a dozen Photoshop how-to books, but says one of the most important things is to understand light.

“You have to know where the light sources are, and make sure there is a cohesive relationship between adjacent elements.”

On creating world-class composite images, he says: “Organize composited elements in layer groups and get familiar with the group blending mode ‘Normal’, as this allows you to apply colour corrections to specific layers without having to link them as clipping layers.

He adds: “It can help to separate out your initial balancing corrections from more localized modelling work and subsequent global colour shifts, so you can readily manipulate the aspect you need to.”

He has a final tip for Digital Arts readers: “An image layer or single colour adjustment layer set to colour blending mode will not work within a layer group set to ‘Normal’, but a Gradient Map adjustment layer will.”