Lilahpops

Create a cool green colour effect with curves

Cross processing is something I have started to experiment with. I find I’m drawn to many of these photos on Flickr - the effect can be quite stunning. I uploaded the final cross-processed result of this image to Flickr and it made Explore soon after.

Here we’ll focus on the green effect you can produce, although you can also adjust your settings for other hues, such as red.

It’s all about the curves

Cross processing can be a very simple GIMP edit if you set and save the RGB colour curves to your GIMP library. You can then re-use the setting again and again with other images. I have a few of these options saved in my GIMP library: one is a general curves adjustment; one boosts each RGB colour channel for retro effects; and now I have a green cross process setting.

Save the setting the first time you use it and it will then be available for future edits.

Auto-levels

In the image above I did a quick auto-levels adjustment Colors -> Levels -> Auto. I played around with the Hue-Saturation and Contrast options but decided to not to use these changes as there is quite a lot of contrast already. It will depend on your image if you need to boost the colour and contrast.

Save your curves setting

Now to the curves. Go to Layer -> Duplicate Layer - a handy option as you can simply delete the layer if you don’t like the results. The settings below are what I have come up with after reading a bagful of articles about cross processing.

Select Color -> Curves and change the individual RGB channels to the settings below:

Red setting

Green setting

Blue setting

Select Save and name your curves something useful, like Cross Processing - Green. You can use this setting for other images you cross process without having to change the RGB values each time. To access your saved files next time simply go to Color -> Curves -> Open.

Click OK and the image now looks like this:

You can also add an almost transparent fill layer of a lime green (to bring out more green) or a fushia (to bring out more red and blue). I’ve decided against a fill layer with this particular image.

Crop and you’re done

I cropped the balcony out of the image which brought more focus to the sky and those gorgeous sunbeams.

Et voila! Click the image to view a larger size in Flickr.

Related cross processing articles

• Brian Auer has a great tutorial on both green and red cross processing over at Epic Edits Weblog
• Check out the impressive results by Danny Ngan at Poo-Poo Platter

Other examples

It’s interesting to see the various RGB settings that are used and leads me to think I should make save a few more curves settings saved to my library.

Here are some other images I have cross processed - with varying degrees of success.

Do you have any handy cross processing tips?

See also:

• Give your photos a retro feel with the GIMP
• Saturate the colours in a photo with GIMP