Converting colour images to black and white

Black and white from your digital camera

The thumbnail images below represent different ways of converting a colour image into black and white.

Some of the differences in the monochrome images are quite subtle.

The images are all about 120k in size. They are JPEG files and are produced from the colour picture using Adobe Photoshop.

Do try some of these techniques on your own images to see the variations.

How were the black and white versions made?

The Tri-X, FP4 and colour filter versions were produced using "Convert to B/W Pro" from the Imaging Factory <http://www.theimagingfactory.com/>

It provides a simple interface to such conversions, although you could duplicate them with various Photoshop techniques, such as channel mixing and others described in the techniques section of the Info and resources page. Keith has added a review of version 3 of Convert to BW pro to our reviews page

We also have a review of the Photoshop plugin Power Retouche Black/white studio which gives a wide variety of effects when converting images from colour to black and white. Includes film types and the ability to selectively alter 'zones' of images.

Some of the photoshop techniques may not be too obvious at first. One such method is using both a channel mixer layer and a hue/saturation layer to give fine control over the conversion, although you should be wary of pushing too far -- unless you are specifically looking to show JPEG artefacts and sensor noise.

Conversion of digital colour to black and white is quite easy and these examples should help with your experiments. Digital black and white does not need a special camera... and even if your camera supports black and white, you invariably get better results shooting in colour and doing the conversion yourself.

Given the size of the images you may wish to download a zipped folder (about 1.6 Meg) of the first set. Clicking on each thumbnail will open a larger image (with notes on the technique) so that you can easily see the differences.

The subtle differences will depend quite a bit on having a well set up monitor (see the Viewing Tips). The colour image here is tagged with an sRGB profile to give a reasonable view on as many monitors as possible.

The image of Old John was also used for testing in Keith's review of the PrintFIX printer profiling system. The same location is used in Keith's article on his first impressions of using digital for B/W landscape pictures. As a long time user of film for his black and white work, the move to digital raises quite a few issues.

Example conversions

		Colour Image
	Channel Mixer 100% Red	Channel Mixer 100% Green	Channel Mixer 100% Blue
	Photoshop Desaturated	"Yellow" Filter	"Red" Filter
	Channel Mix 66-24-10 rgb	"FP4" film effect	"Tri-X" film effect
	Photoshop Convert to Gray	Channel Mix 60-30-10 Hue &Sat +40 +60	Photoshop Lab conversion
	2 Hue/Saturation layers	Photoshop Action	DR_Custom
	2 H/S layers (IR effect)	Hue/Sat layer and a curve layer	Layer blending mode

The original colour image was taken using an Olympus E-20 digital camera and adjusted to give a good rendition of the actual scene. It was resized down to ~640x480 and sharpened for web use. The black and white versions have received no processing after the conversion (such as adding 'grain' to the 'film' versions :-)). The differences are more pronounced if you have a more fully saturated original picture -- all part of the variations you can try!

One adjustment you might like to try after your conversion is to run Unsharp Mask at around 5-20% intensity, with a radius of 50-150 (threshold = 0) This does not sharpen in the way you might ordinarily do with USM, it provides a subtle contrast enhancement and for some images it is very effective, particularly where you have a big dynamic range in the picture -- for example between the shadowed wall and cloud. I often run it after using the Lab conversion technique. Give it a try in association with one of the methods on this page. It's also known by the acronym HIRALOAM (HI RAdius LOw AMount - Apply an unsharp mask filter with high radius and low amount settings).

The view above is of "Old John" a folly built on a high hill overlooking Leicester (a few miles to the other side of the hill). It is in Bradgate Park, a popular place to go for a walk for the people of the region. There is more information here and here. Keith Cooper first visited the Bradgate area as an undergraduate, doing his Geology degree at the University of Leicester. It is where the oldest fossils in the UK (Charnia) were first discovered in 1957 and provides a glimpse of some of the earliest complex lifeforms, over 500 million years ago. There are some more pictures of it and the Moon in Keiths review of Nik Sharpener Pro.

Other Methods

I'm always happy to hear of any alternative methods available, so please let me know. There is a page with more details on other types of B/W conversions, which has details of some methods which do not really produce one simple 'example'.

We also have an article on why it may be better to convert your 8 bit RGB images to 16 bit before converting to black and white.

The second set shows similar B/W conversion effects on completely different source material

The colour original was taken in a brightly lit fast food outlet at about 2am. The mix of fluorescent and neon lighting makes it somewhat difficult to get a good white balance (an 18% grey card not being at hand) Taken with an Olympus E-20.

		Colour Image
	Channel Mixer 100% Red	Channel Mixer 100% Green	Channel Mixer 100% Blue
	Photoshop Desaturated	Photoshop convert to Gray	Photoshop Lab conversion
	Channel Mix 54-44-12 rgb	DR_Custom by David Riecks

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