On 13/10/2004, at 1:52 AM, prodig-digest wrote:
Date: Mon, 11 Oct 2004 21:46:19 +0100 From: "Malcolm Jeffs" Subject: [PRODIG] Digital equivalent of "Cross-Processing"
Can anyone tell me how I might achieve in PSCS an effect similar to that of
cross-processing (C41/E6)? I have tried to mimic this by messing around in
"Curves" but to no avail. Film cross-processing was always a bit "hit &
miss" - I am hoping that digitally, things might be more controllable (once
I've got a grip with the basic procedure that is!).
Regards,
Malcolm Jeffs
What follows is based on a technique I have used to rescue studio shots taken in 8bit under the wrong wb setting and match to existing shots in the same conditions. (Not my shots, I only shoot Raw in the Studio. Why would you do anything else:-/)
I made this, including the 16 bit conversion and back, into an action which matched over a hundred images in no time.
The following text has been modified to apply to the above request. Let me know if something does not make sense.
You need two files from a Macbeth Colour Chart or similar.
Step 1, Photograph a Macbeth colour chart on film and process using the processing technique you want to emulate. This is 'Shot 1'
Step 2, Photograph a Macbeth colour chart under normal conditions. This is 'Shot 2'
Step 3, Scan or Open 'Shot 1' and 'Shot 2' in Photoshop (Shot 1 can be modified at this point if it is not quite what you intended. Shot 2 should be colour corrected so that all grey patches are neutral, this will give you a common starting point for future conversions and is more important if using different cameras, lighting etc).
Step 4, Set colour mode to 16bit in both images (Starting Step 1 in Raw or 16bit and using the same depth for future sessions is probably a good idea)
Step 5, Open your info palette (F8) and set your eyedropper to 3x3 or greater
Step 6, With 'shot 1', using pen and paper note the rgb values for each and every grey patch and some of the colour ones too.
Step 7, Close 'shot 1' and in 'shot 2' open Curves
REMEMBER to use 16 bit mode
Step 8, Position your mouse over the first grey patch and transfer the values as follows. The mouse must not move after the first click and the info palette (F8) must remain visible.
Type Command 1 to switch to the red channel
Command click (Sorry, I don't know the PC equivalent) and while watching the info palette use the up or down arrows on your keyboard to match the value for red at this position.
Type Command 2 to switch to the green channel
Command click again, and while watching the info palette use the up or down arrows on your keyboard to match the value for green at this position.
Type Command 3 to switch to the blue channel
Command click again, and while watching the info palette use the up or down arrows on your keyboard to match the value for blue at this position.
Step 9, You may now move the mouse onto the next patch and repeat Step 8, keep repeating for each grey patch until finished.
If you noted the values of some colour patches you can use them now as a cross check. This technique may result in quite wild curve settings and it may be impossible to match some of the patches, in this instance just use your common sense.
DO NOT CLICK OK YET
Step 10, If recording an action this step is unimportant, you may wish to do it anyway.
Save the curves modification and put it in a safe place
Step 11, You may now click OK in the curves dialog
Step 12, Convert mode back to 8 bit and save your new file however you wish. I used an action with a batch command to save in a different location without overwriting the originals.
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