Monochrome from Colour


By Ian Lyons



A Computer Darkroom Tutorial

How often have you found yourself taking photographs with the camera loaded with colour film, and thought "if only Id brought some Black & White film I could get some really snazzy pictures". For some it isn't a problem, they may have two cameras or even one of the medium format units with interchangeable backs. But for the bulk of camera owners "no choice" is usually the norm.



Well it really doesn't matter much any longer, especially if using Photoshop, since changing from colour to monochrome is simply a matter of a few Mouse clicks and bingo! The most obvious way to get black and white from colour in Photoshop is simply to do a mode conversion from the menu bar - "Image > Mode > Grayscale", this will discard all colour information. Personally I find this method produces rather flat images that require quite significant amounts of post scan adjustment in Photoshop. However, a better option exists in the form of "Channel Mixer".

"Channel Mixer" is  a very useful image adjustment tool that allows the user to mix/blend the colour channel balance of an image. In fact so powerful is this tool that we can easily replicate the effect of placing red or yellow filters over the lens when using black and white film. Enough of the waffle, let's get on with the method.



Advertisement Pillar, Berlin - a pretty ordinary record shot, lets see if we can make it better!

The starting point will always be a full colour image in RGB mode. Most film scanners will find capturing the full range of colours, etc. pretty easy, but had the original been in black and white it's usually a different matter. The image above is the raw scan imported directly into Photoshop via my Nikon LS30 film scanner using LaserSoft SilverFast software. 

The following steps will take us though the process of creating a simple black and white image, followed by a sepia toned image and finally we will create split toned image.

The Process: -

Step 1 - Channel mixer set-up

  • In Photoshop open a full colour RGB image as per the above example

  • From Photoshop menu bar select "Layer  > New Adjustment Layer  >  Channel Mixer"


  • Make sure "Monochrome" is selected.


Channel Mixer Dialog

By selecting the "Monochrome" checkbox we are instructing Photoshop to convert the full colour RGB image into a monochrome preview, but the image still retains all the colour channel information. Note that in the above screenshot of the "Channel Mixer" dialog that the "Output Channel" is Gray; we cannot change it. However, even though the red channel is initially at 100% and the green and yellow channels are at 0% we are free to mix them as we see fit. The objective is to optimise the image whilst ensuring that total percentage for the three channels adds up to 100% or as near as is possible. Interestingly combinations adding up to more or less than 100% will be either darker or lighter than the original colour image. So don't be afraid to experiment!


This image is rather flat, and the separation between the advertisement pillar and sky is poor

Step 2 - Optimising the mix of colour channel information for black and white

  • Simply move the red channel to a value less than 100%

  • Adjust the green and/or blue channels to get the desired effect

  • The following example has the effect of brightening the overall image and also separates the sky and mailbox


Channel Mixer set for balance of red, green and blue


Black and White - Advertisement Pillar


As we can see the process involved is really VERY easy and the effects are only limited by our imagination. Once we get the desired overall effect it's possible to fine-tune the image further using image adjustment "Curves". However, it doesn't finish there, the number of options we can take to finish our image is really quite staggering.

Step 3 - Adjustments for full colour toning a black and white image

Whilst our image is now giving the appearance of a black and white picture it's still in RGB colour mode. We can now add colour in a number of different ways. The description that follows is for a Sepia tone effect, but we can adjust for blue, pink, etc.

  • From Photoshop menu bar select "Layer > New Adjustment layer > Color Balance".

  • When the "Color Balance" dialog appears we make sure the "Tone Balance is set for Midtones".

  • Next we adjust each of the colour channel "sliders" until the desired colour effect is obtained. Remember that since we are using adjustment layers the changes can be modified and fine-tuned at any time.

  • Now we repeat the "Color Balance" adjustments with the "Tone Balance" set for  "Shadows". The actual balance of colours should normally be roughly the same as used for the "Midtones" adjustment.

  • Once we're happy with the balance we can flatten the image using "Layer > Flatten Image".


Color Balance dialog - midtones settings for Sepia Tone effect


 Sepia Toned shadows and midtones in Photoshop

Step 4 - Split toning

Split Tone printing was once the domain of only a few very talented darkroom printers. However, using Photoshop we find "Split Toning"  is really very simple and a highly effective way of presenting our images. A split tone print is a black and white print that has only been partially toned or a mix of toning effects have been applied. When done correctly the effects can be really very subtle, and very attractive.

  • We begin by creating the Black and White image using the "Channel Mixer" method described in Step 1, when satisfied with the tones we flatten the  image using the "Layer > Flatten Image" command.

  • Make a new "Adjustment Layer" i.e. "Layer > New Adjustment layer > Color Balance"

  • When the "Color Balance" dialog appears we set the "Tone Balance" for "Midtones and Shadows".

  • Adjust the "Color Balance" of the midtones and shadows for the desired effect. This will be our base colour.


Color Balance dialog - midtones/shadows settings

  • Now we repeat the above exercise for the "Midtones and Highlights" but use contrasting settings.


Color Balance dialog - midtones/highlights settings

  • Next right mouse button click the "Color Balance" layer in the "Layers" palette, and select  "Blending Options".


Layers Palette



Photoshop Layer Style dialog

  • Now we select the "black triangle" below "This Layer:" in the "Blend If:" section of the "Layer Style" dialog.

  • Move the black triangle to approximately 50

  • Hold down the "Option/Alt" key on the keyboard and left mouse click the black triangle to split it.

  • Now move the right half of the black triangle to about 180/200


Photoshop layer Options dialog after adjustment of blending slider

Unfortunately the effect might not be as obvious on-screen as in print, hopefully you will see that the shadow areas retain the sepia effect, whilst the midtones take on a slight blue tone. The variations are unlimited, and certainly allow for lots of experimentation.


Advertisement Pillar, Berlin - Split Toned in Photoshop



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