There are many techniques for converting your colour image to monochrome. I am just going to show you what I do. This is not the only way and I am happy to be shown alternatives. I use adobe photoshop. Perhaps it is best to start with an understanding of some principles.
- I want to display a full range of tones from black to white. I don’t like muddy grey monochrome images – they need to be punchy. To achieve this I want good contrast. I will use curves and clarify to enhance my contrast.
- Sharpness is harder to achieve in monochrome, but looks terrific when you do achieve it. Sometimes a nice crisp colour image turns into a blurred and not quite sharp monochrome. Beware of over-sharpening which can create luminance noise and halos and sharpening artefact.
- The 3 colour channels in the image have a different and distinct monochrome appearance. You can blend these signatures to get a more creative result. It is similar to using coloured filters with a film camera and black and white film. There is a “black and white” tool in Photoshop that will make this job quite simple to do.
- Unfortunately you can very easily get colour noise if you push the colour channels too hard. This is a common problem if you reduce the blue slider to make a sky darker. The sky appears to have rice grain blobs all over it. Quite disappointing if it was previously silky smooth. It happens because there just aren’t enough red and green pixels in the sky. This is worse when you are working with a jpeg file, and better if you have raw images. As a precaution don’t push the coloured sliders to the extreme. Stay in the middle 2/3 of the range. If you can’t achieve the effect you want without noise, it may be better to darken the sky using a different strategy.
- When choosing an image to convert, look for good texture, strong form and good contrast. Don’t restrict yourself to converting only images with very little colour to start with. Sometimes very colourful images make good monochromes. Try to imagine how it will look in the new medium.
- You need to use your skills to enhance the subject. In monochrome colourful backgrounds are made less distracting. Fantastic. But beware. You will also loose colour in your subject. It may get lost if it blends into the background. You will have to maintain a degree of separation in tones to make it stand out. If it is already a different tone – then well and good. If not, you will have to create a difference. This is where the colour sliders can help you. Alternatively you might use dodge and burn strategies. You need to take control of the image to make it a stronger.
Example – Field of Daisies.
I was walking in the Yorkshire Dales and came across this field of yellow daisies with a barn on the horizon and an overcast sky. The reason I took the photo was because of the mass of daisies. Perhaps the photo is not a wonderful testament to what it was like on the day.
When I remove the colour information and convert the image to grey scale, I get this uninteresting picture. The grass and the daisies are an identical tone.
Instead I use the “black and white” adjustment layer, and play with the sliders. I discover that by increasing the red and yellow, but reducing the green sliders I can make the daisies stand out from the grass.
The sky however remains relatively uninteresting. I can reduce the cyan slider, but it makes the sky very noisy. I decided against doing that. In this case I select the sky using the magic wand tool. I then create a curves adjustment layer and create a steep S curve to increase contrast in the sky. (Note that the steepest part of the S curve coincides with the hump in the histogram)
Lastly I accentuate this changes by creating a dodge and burn layer. What I actually do is create a new layer over the top of the image and adjust the blend mode to “soft light” Then with a fully feathered brush I add black and white to this layer (at 50% opacity) to darken or lighten the final image. So that you can see what I do, I have reproduced this layer below. I have overlaid the dodge and burn layer over a plain red background, so you can see where I added white and where I added black.
The final result is at the top of the page. I will let you be the judge. What do you think? Is it worth the effort? Does it strengthen the image? Is it better than the grey scale conversion?
I hope that this demonstration has been helpful. I am happy to answer questions if you have any.