Digital cross-processing C-41 as E-6

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").
It is no surprise that this causes wild color and contrast shifts and this is usually a process of extensive trial and error.
With so many possible permutations of film and processing techniques,
there is no right or wrong for that matter cross-processed appearance.
The most common combination is C-41 as E-6 and luckily for us, there is a quick and easy way
to replicate this effect in Photoshop.

These images usually have high contrast and blown out highlights,
and because of that we are going to use Curves as our primary tool here.
We will make a new Curves adjustment layer ( Layer > New Adjustment Layer > Curves )
and select the red channel in the dropdown box of the Curves dialog box.
On the red channel we move the upper right point (the red highlights) a little to the left,
we are also going to create a bit of an S-curve on the red channel.
By doing this we have darkened the red shadows and pushed the red highlights towards being blown out
(which is image dependent really).

After the red Curves channel it is time for the green. Here we are simply going to make a slight S-curve
and that is all we are going to do here.

The red and green channels in the curves dialog box

Next we have our final channel, blue. 
On the blue channel we are going to push the lower left point (blue shadows) up
and the upper right point (blue highlights) down,
in effect lowering the contrast of the blue channel.

The blue channel in the curves dialog box

After this you could make a decision (this will be on a image to image basis) to create a second Curves adjustment layer to push the global contrast of the image even further,
however this layer should be set to Luminosity blend mode, otherwise it will cause a unwanted color shift.

Hop over to my photoshop actions pack if you want this cross-processing technique
along with several others in actions format.

The second Curves adjustment layer


The final image, rollover to see a before and after