Clive R. Haynes FRPS

Using the facility of ‘Channels’ to produce a monochrome image from a colour enables us to utilise each of the three channels as if we were shooting a scene with different colour filters, Red, Green and Blue.

Depending upon the content of the scene we can select a filter which will have the effect we desire.

Remember that the colour selected will render tones nearest to the ‘channel colour’ as lighter/brighter. Tones of the corresponding complimentary colour will become darker.

E.g. the Red Channel will cause blue skies and cyan coloured seas to darken and red/orange/ yellow tones to lighten – just as in traditional monochrome photography.

The Blue channel will cause blue skies to lighten and red/orange/yellow areas (brick buildings or lips perhaps) to darken.

The Green channel will lighten foliage and darken blue skies to an extent. Magenta (as a complimentary colour) will darken. It’s just like having colour filters available after shooting the scene.

Remember however, that we’re starting with a colour image. A monochrome negative, even if converted to RGB colour will not exhibit this response. For monochrome film you’ll still need to shoot with the appropriate filter.

Shooting with a colour film means that we can choose later how we treat it, either as a colour or monochrome image and then what filter or combination of filters to use. The best of both worlds!

This is the procedure

Open the colour image.

Make certain that the image is a Background layer, if not, ‘flatten’ the layers(via Layers > flatten).

An alternative method of making a Background layer is: -

For Photoshop 6 make a new background via Layer > New > Layer from Background

For Photoshop 5 / 5.5 make a new background via Layer > New > Background

However, the image still needs to be on just one layer - the Background so 'Flatten if you need to.

Go to the Channels palette and click the right facing arrow at the top right hand corner. From the drop-down menu choose ‘Split Channels’.

The channels will divide into three ‘windows’, Red, Green Blue (labelled R, G and B). Note that each channel displayed will have its own characteristic response to the scene depending upon the colour combinations of the original.

Next, go to File > New The dialogue box that appears should offer the same size and resolution as the image you’ve just been working on. Should this not be the case, then type in the correct values. You may need to return to the original image to check on the values – look up the dimensions and resolution via Image > Image Size.

Copy and paste each of the monochrome R, G and B windows to the new image file. Each will appear on its own layer. Arrange them into a satisfactory order to facilitate the ‘mixing’ you need.

Adjust the opacity of each layer to produce the image required.

Add an ‘Adjustment Layer’ or ‘Layer Mask’ to each to enable fine control and subtle merging between the layers.

For information on ‘Adjustment Layers’ and ‘Layer Masks’ see another paper – ‘Delving Deeper Into layers’. See link below.


With the original colour image open, experiments can be made with various hue & saturation settings.

For example, make only one channel visible, say the Red (Go to 'Channels' and switch off all the 'eye' icons except for the Red Channel). NB: make certain that all the channels remain 'active', that is they are all blue shaded. If all channels are not active you will be unable to select 'Hue & Saturation'.

The image will become monochrome, as 'seen' through a red filter.

Now, go to Image > Adjust > Hue & Saturation.

Use the Hue & Saturation sliders to alter the colour range and see how it affects the rendering of the monochrome information.

To target specific colour ranges: In the Hue & Saturation dialogue box, go to Edit and from the drop-down' menu and choose a colour.

This highly targeted and selective method of adjustment will affect all the other channels too. This method can be used prior to 'splitting' the channels, however, it will have also made significant changes to the filtration of the other channels as well. It may best be employed without 'splitting' the channels.

If one requires a differently adjusted Hue & Saturation setting for each channel then the best method is to make separate colour copies of the original image. Make the necessary changes, then 'copy & paste' each adjusted channel to a new document. This will result in layers made from three separately adjusted originals, all in register. Note: the resulting composite will appear in colour - no doubt a very strange colour combination too!

Convert this new image to Monochrome (Image > Mode > Monochrome > 'Don't Flatten'). Each layer may then be blended and adjusted as required.

Delving Deeper Into Layers (V5.5)
Delving Deeper Into Layers (V6)
Know-How Contents
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