'Colour Diffusion'

Clive R. Haynes FRPS

Here's a subtle technique that will, for the right image, create a softly romanticised version of the original.

The basics steps comprise copying the original image, turning the picture to monochrome, then using the copy to overlay the colour information only with blur applied.

The effect is subtle and shows more clearly on a print. The example below illustrates what can be done but you'll need to carefully compare the 'before & after' images - As I mentioned it is subtle but the effect is there.

The colour has spilled and merged from one area to another and this has the effect of pleasingly homogenising the colour tones.

Below: 'Before'
Below: 'After'
The Method
Our Working Image with rich, evening tonality

(Quick-Keys shown in brackets)
After opening the image, make a copy layer by either dragging the Background layer onto the New Layer icon at the base of the Layers palette
or by Select > All (Ctrl + A)
Edit > Copy (Ctrl + C)
Edit > Paste (Ctrl + V)

Layer Palette - after making the Copy Layer

Turn off / deactivate this layer by clicking on the eye icon.

Return to the Background Layer and make this 'monochrome'.
This can be done either by: Image > Adjust > Desaturate (Ctrl + Sift + U)

Above: The Monochrome appearance

Alternatively, 'Channel Mixer' can be used to refine the tonality of the monochrome image.
Channel mixer allows more adjustment. To use this method, click on the Adjustment Layer icon at the base of the Layers palette (half black / half white circle) and from the drop-down menu, choose 'Channel Mixer'.
Tick the 'Monochrome' box.
Adjust the 'slider' controls to give the most satisfactory black & white image.
Click 'OK'.

See 'link' below for more information re 'Channel Mixer'

Return to the copy layer and reactivate it (click on the eye icon).
Set the 'Blend Mode' for this layer to 'Colour' ('Overlay' is another option). The menu for 'Blend Modes' can be accessed via the drop down menu arrow at the side of the word 'Normal' - top left of the Layers palette.

Layer Palette with Copy Layer set to 'Color' Blend Mode

Go to Filter > Blur > Gaussian Blur.
The amount of blur to apply is dependent upon the image file size - the larger the image file, the more blur you'll require. Move the slider to gradually blur the colour. You will notice that as the blur increases the colour wash effect will gradually become more diffuse and harmonisation of the colours will begin.
When there is sufficient blur for the picture and the mood you wish to convey, click 'OK'.

As a rough guide, the image from which this working example was taken was a 20mb file and I used a Gaussian Blur setting of 35.

That's it.

The final result is below.
The 'Before & After' images are difficult to compare as jpeg pictures. In reality, they are, A3 prints and the 'Diffuse Colour' version appears more pleasing and gentle with an old-world, romantic atmosphere.

The final image with gentle tonality and subtle diffusion

For another approach and also for additional information about this technique, visit my pages about 'Pen & Ink Technique'. Towrads the end of these pages, the effect of adding 'blurred colour' is discussed and illustrated. Click on the 'link' below.
Related Topics
Channel Mixer
Pen & Ink Technique
Know-How Contents
e-mail CRHfoto