My starting point here is the small image on the right. It was taken at Ilfracombe, Devon, on colour film, as MS Oldenburg returned from a trip to Lundy Island. The light was fading and these silhouetted people were awaiting our arrival at the Quayside. There is not a great deal of colour in the picture, but for a hint of blue in the sky, so it is virtually a monochrome anyway.

A useful preliminary before toning is to convert to greyscale. In this example I have used Channel Mixer. If you haven't got this option use greyscale mode and revert back to RGB; don't be tempted to use the Desaturate or Colorize options at this stage - they're not the same, and some tonal information is lost. See Monochrome page for more details.

Introduce a particular hue. In this case I used "Colorize" to obtain a general sepia cast. Choose: Image>Adjust>Hue & Saturation, and check the Colorize box. I chose a hue value of about 40-50 and set saturation to -25. Colorize won't affect tonal differences (luminosity values) here, since colour information has already been removed. Alternatively, the colour balance controls may be used to introduce colour. This has the advantage of being able to select a particular tonal range (shadows, midtones, or highlights) to which colour is applied.

This is the fun bit. Choose: Image>Adjust>Replace Color, and make sure the preview box is checked and that you are in mask view (no colour visible). In this example I then clicked on an area of dark cloud with the eyedropper. If your version of Photoshop doesn't have an eyedropper, simply use the mouse pointer instead.

At this point Photoshop will place a black mask over the rest of the image, leaving the area selected to show in white. The extent of the selection is controlled using the Fuzziness slider - in this case to a tolerance value of 68. There are three other sliders: for hue, saturation, and lightness. I set hue to 171 and saturation to -33. At the default level of saturation (0) the blue was too intense.

I had to experiment, for a while, with different selections and settings, before I was satisfied with the result. Sometimes it works, sometimes it doesn't - that's all part of the magic.

Finally, I couldn't resist including two more images, originally taken somewhere in the Gower, Wales, by Dr David Pelling - a fellow Photocraft member. David likes to experiment with alternative processes, such as Lith printing. As a challenge, I borrowed his negative to see if a similar effect to the genuine article could be achieved in Photoshop. The above shows my first attempt, but I have to say that it does not reproduce as well on the web as the actual print, which has a lot of fine edge detail and subtlety of colour. I have also muted the pink toning which accompanied the original print. Replace Color was used to give a hint of green to the midtones.

I have included these two images to further illustrate the use of Replace Color, though I have to admit to employing other methods to achieve the dark edges associated with Lith printing. In this version I have used a blue-grey hue for contrast.