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Cross processing effects
Apologies first to Photoshop 4.0 users for not realising earlier that the instructions I initially provided for this technique related to version 3.0 only and would not work with version 4.0. After years of giving Channel Operations a wide berth, I finally discovered what a valuable asset they are for techniques such as this. More images to follow soon on this page.

The cross-process technique is kind of similar to a colour manipulation method outlined in a previous Design matters feature where colour shifts were created by multiplying or screening the densities of individual colour channels. Here, the technique has been adapted to match what happens when colour negative C-41 film is processed in E6 transparency chemicals. The highlights become compressed in the yellow and magenta layers, so pure whites appear pinky-orange and shadow tones will contain a strong cyan / blue cast. Most of the mid to highlight detail (like skin tones) will get compressed or lost , which is probably why many music photographers prefer to photograph their spotty teenage subjects this way when there's no budget for a make-up artist. This is a destructive digital technique, but arguably less so than if you were to follow the photo-chemical route. Once film is over processed there is no way of restoring lost detail. One can pretty accurately match the film colour effects with Photoshop and choose to retain more detail than you would get otherwise. Remember to keep a close eye on the info box! You may end up with some very heavy ink percentages.

1 Before commencing , it is important that the image should be in CMYK colour mode with the levels and curves fully corrected. In the case of portraits, the skin tones should ideally be nice and light as shown above. Prepare the screen layout with the channels palette visible. Activate the Yellow channel by highlighting it, but keep the eye icon for the CMYK channel switched on - this enables you to see the colour changes as they happen.


2 Choose Image > Apply Image. Check the Invert box and set the blending mode to Hard Light between 40% - 50%. Check the Preview box as well to preview the channel operation effect in the image window.
3 After applying the effect to the image, you should see the colour change to look as if has has been photographed through a strong yellow filter.
4 Repeat the process on the Magenta channel, but take the opacity down to somewhere in the region of 25% - 50% and set the blending mode to Normal (or you could experiment with Hard Light).

5 Go to the Cyan channel. Choose Image > Apply image again and this time do not check the Invert box and set the blending mode to Multiply at 100%. That should be enough, though sometimes it helps if you repeat this operation again at around 30% - 50%.

6 The image should now begin to look cross processed, but still needs further adjustment using the curves command. These CMYK curve settings were used to enhance the contrast in each of the colour channels and overall lightening the image in the CMYK and K channels. (Note that I worked with the brightness bar inverted from its default setting).


7 Here is the final image. Pay special attention to these shadow areas. Open the Show info palette and take eyedropper readings. The total CMYK percentages should not exceed 355% of which 85% is black (depending also on the printing stock you are using). Anything beyond that will print as solid black and detail such as there is will be lost.

I used this technique with a few variations on copies of the original image, some were taken to stage 2 only and adjusted with Hue / Saturation. I also made a rough mask of the background area and filled with different colours.

Extract originally published in MacUser 1996. Copyright: Martin Evening

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