An old technique has a new lease on life in the digital world of Photoshop to create interesting images from both compact digital cameras and from dSLRs.
Back in the dark ages when I shot film 🙂 I used a creative technique called tri-color photography. In this technique I would set my camera, then a wonderful Canon T90, into multiple exposure mode, mount a Cokin filter holder and then, with the camera on a good tripod, shoot three exposures onto the same frame, one through a strong red filter, one through a green and one through a blue. The resulting transparency (that’s what I normally shot) would show a roughly naturally colored image of anything that did not move but wonderful color effects on subjects in motion. The technique worked well but it was not without its issues. Even with the Cokin filter system there was a risk of moving the camera or adjusting the lens zoom or focus while changing filters. Also, whilst in theory the three filters should have given a result in natural color, there were the inevitable differences between the exact exposure required through the three filters so that the result always had a color cast, though sometimes a small one. But the technique worked and I got some lovely images, especially of the sea, that I exhibited as large Cibachromes.
Now that I work digitally this technique is even easier. Digital cameras have the red, green and blue filters built in, but few have the ability to take multiple exposures. Thankfully there is no need for it.
Digitally, the tri-color process consists of the following steps:
Mount the camera on a sturdy tripod and either use a cable release or the self-timer;
Take three shots of a scene with some part of it moving;
Open the three images in Photoshop, Paint Shop Pro or similar software;
Copy the green channel from the second image and paste it into the green channel of the first image;
Copy the blue channel from the third image and paste it into the blue channel of the first image;
This gives you a composite image with the red channel of the first, green of the second and blue of the third.
You want to time the shooting so there is opportunity for movement to occur between shots. Generally, with things like the ocean or trees on a windy day, you can just shoot. With clouds moving you may want to give more time between shots.
Here is the step by step in Photoshop:
- Open three images in Photoshop. Select the first one;
- Do a Select All
- Activate the Channels palette and click on the Green channel
- Switch to the second file and select its Green channel
- Select All and copy the channel to the clipboard
- Switch back to the first file and paste the clipboard into the Green channel
- Select the Blue channel
- Switch to the third file, Select All and select the Blue channel
- Copy the Blue channel to the clipboard
- Switch back to the first file and Paste the clipboard into the Blue channel
- Click on the RGB channel to see the result
- The result after a mild sharpen
The above is, if you like, the classic approach. There are lots of variations you can make.
For example, if you shoot infrared, as I do, you can do a slightly different sequence:
- Open the three IR images
- Select the first image, do Select All and then select the Green channel
- Switch to the second image, click on the Red channel, do Select All and Copy
- Switch back to the first image and Paste the Red channel from the second image into the Green channel of the first
- Select the Blue channel
- Switch to the third file, select the Red channel, do Select All and Copy
- Switch back to the first file and Paste the Red channel from the third image into the Blue channel of the first.
You can, of course combine the green channels, in which case you move the channels into the middle file, moving the Green from the 1st into the Red of the 2nd and the Green of the 3rd into the Blue of the 2nd.
Remember, the resulting image is just a starting point for further work. You can swap the channels around till you get the color effects you want, do individual adjustments on the channels, apply blur or sharpen and so much more.
These tri-color processes work and work well. Some subjects work better than others, as is true of any technique.