Cross-processing is developing color print or slide film in the wrong chemicals — for example, color negative film in slide chemicals ("C-41 as E-6") or slide film by the color negative process ("E-6 as C-41"). Not surprisingly, this causes wild color and contrast shifts and requires lots of trial and error. But for a period in the 1980s and 1990s, cross-processed images were very much the vogue, with Nick Knight's fashion and studio work being arguably the most influential.

     With many possible permutations of film stock and processing technique, there is no single, identifiable, cross-processed appearance. The most common combination is C-41 as E-6, in which slide chemistry is used to process color negative film, and it's a quick job to imitate it in Photoshop. Image contrast is usually high with blown-out highlights, while the shadows tend toward dense shades of blue. Reds tend to be magenta, lips almost purple, and highlights normally have a yellow-green color cast.

As for subject matter, try fashion or portraiture, but there's no need to restrict your imagination. I chose an elegant outdoor portrait shot — the skin tones and red lipstick look especially striking in cross-processed images.

TIP
To save your curve to a file on your hard drive, just click the Save button. Applying the same cross-processing adjustment to other images is a simple matter of loading it with the Load button in the Curves dialog box.

STEP 2
Select the Blue channel and drag the curve's top-right point downward. It doesn't need to be much — just enough to take some blue out of the highlights. Then drag the curve's bottom-right point up a little, blocking up the Blue channel in the shadows.