Styles come and go in everything, even photography. The latest style for black and white seems to be a very high contrast model. The method I want to demonstrate harkens back to a different time, a time when total tonality was king. No I don’t want to live in the past and even though giving an image a wide tonal range might take its cues from the past, it also allows you to use tonality for artistic purpose.
In the past when I did my black and white conversions I believed that preserving the luminance (Lightness) of the shades of colors (represented as tones of gray) was essential. In order to accomplish that I used Convert to Grayscale as my method as it was the only one that accomplished that exactly and quickly every time. It worked very well for me until I discovered painting with color channels. In Figure 1, you can see how different methods of conversions change Primary and Secondary colors.
What you’ll notice pretty quickly is that Desaturate really does a bad job and turns everything the same tone. Grayscale preserves the luminance of every shade. The purpose of showing all the color channels is to show how each one affects the different shades.
So while Convert to Grayscale accomplished for me a technically correct image, it ran me straight into the Artistic Wall. The problem is when converting 16.7 Million shades of colors to 256 tones of gray, there will be a lot of overlap. Many different shades will end up being the same tone.
In photography, we use lightness to draw the eye− the eye will go to the brightest area or area of most contrast−but also use color to draw the eye. Some colors are dominant, some recessive. So what happens when upon conversion that dominant color and that recessive color become the same tone? What draws the eye to our subject in the image is lost! There is also lost detail too. Look at the basic comparison in Figure 2, Original image, Convert to Grayscale and Paint with Color Channels−The difference is easy to see.
Using different color channels changes the luminance value of the converted shade. A yellow flower could look white, gray or black depending on the color channel used in the color mixer in Photoshop, or by mixing channels you could achieve nearly any tone you want. The problem with just using the color mixer “as is?” It applies the conversion globally.
But what about using it locally, the red channel on the cloudy sky because it brings that out best, the green channel on that purple flower and the blue channel on the wheat colored straw? That’s what this method is all about, using Color Channels and Layer Masks to apply that color channel (and therefore that luminance value) in an artistic fashion. We can use lightness to draw the eye to where we want to direct it.
With this method, you can do this without having the problems that would occur with just dodging and burning your way to different lightness values. It’s quite different in that it does not introduce noise or other damaging artifacts from changing the lightness of an image. And quite honestly achieves things that are nearly impossible using lightness adjustments such as the subtlety of tone between two similar shades. It is also non-destructive and totally editable.
If you are familiar with using the Color Mixer and also Layer Masks in Photoshop this method is quite simple.
I start by opening my image and then going to the Channels Palette. I click through each color channel to see its effect on different areas of the image to get a better idea of what channels I want to use in the image. While using all three channels and layer masks are possible, I find for most images, just two channels suffice.
1. I add my first adjustment layer by going to Layer>Adjustment Layer> Channel Mixer. When the Channel Mixer setting dialog comes up, I drop down the channel to Red (it’s actually the default) and then click the monochrome box. Figure 3.
2. Above that layer I add a second layer repeating the process but this time choosing either the green or blue channel before I click the monotone box. Once you determine what you like to use you can make some actions to automate adding two or three layers and different combinations of color channels.
Now you can set about to paint the color channel you want to the desired areas using Black to conceal and White to reveal (and shades of gray if you want to mix channels).
One part of this may be different than how you are used to working. Usually when using layer masks, when painting with black it reveals the layer below. In this case, we work on the middle layers mask (the Red Channel) and painting in black reveals the layer above to the color layer on the bottom. Revealing that channels effect on the color layer.
In Figure 4 you’ll see what that mask looks like, and also the Channels and the layer palette with layer masks. Red area indicates where the red channel is masked off to reveal the Green channel above.
Red and Green Channels
The Red Channel: The red channel adds the drama to the sky that I prefer. However, the flowers have absolutely no detail to them and are blown out.
The Green Channel:The green channel gets the flowers perfect. There is detail throughout even with just the subtle tonal differences between the petal ends and the bottom and stamen area in the center. You may say well why not just use the green channel then. Unfortunately the sky just doesn’t do it for my eye, the blue area is too close in tone to the green area and I want the viewer to look at the flowers first, not the sky.
Finally, here is our “Painting with Color Channels” version. For me it just gets everything right from the dynamic sky to the highly detailed flowers. I feel it has as full a range of tone as possible. You could not achieve that separation of tone with any dodging/ burning technique or lightness adjustments. Bear in mind none of these images have any post-processing on them except for the conversion. So you can take the image from here and now make any needed density adjustments knowing that you started with an image that has great range of tone and very little noise or artifacts. It’s not for every image but it may turn that one you were about to trash into a treasure.