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It's not unusual for photographers to want to convert a color image into a black and white one. Sometimes the image was shot on color film, or was shot in digital color, but for whatever reason, the photographer feels the image would look better in black and white. There are a number of different ways to make this conversion. This tutorial will show you how to use Photoshop's Calculations command to make a black and white image. The calculations method is great for creating contrasty black and white images that emphasize texture, particularly in skin.

First, some basics: digital images are made up of thousands of colored dots known as pixels. Scanners and digital cameras capture a grid of pixels. This grid creates a picture when viewed as a whole. The color of each pixel is determined by the different intensity (luminosity) levels of the primary colors red, green and blue. On a typical computer image, luminosity values range from 0 (none, dark) to 255 (full intensity of that color). Combining red, green and blue with this particular range of luminosity levels, a computer can create around 16.8 million different colors.

Photoshop makes "maps" of the luminosity levels of red, green and blue in each image and calls them "channels." Channels are strange things that might take a little bit of thinking to fully grasp, but it's worth understanding. For example, a reddish pixel will appear light grey or white in the red channel, because it has a high luminosity value of red. That same pixel would appear much darker in the blue and green channels. There's an additional "grey" channel which is just the overall luminosity of red, green and blue channels, exactly like the desaturated image above. You can view the different channels by clicking on "Channels" in Photoshop's Window menu, and toggling the eyeball buttons beside each one.

Now let's say we want to take this image and convert it to black and white:

The easiest way to do it is to just use Photoshop's Hue/Saturation adjustment, and drag the saturation slider all the way to the left to "desaturate" the image. Most photo editing programs have a desaturation command, so you don't actually need Photoshop to use this method. Desaturation sets red, green and blue equal values, while retaining the overall luminosity of each pixel. Making a pixel's red, green and blue values equal causes the pixel to turn grey.

The problem with the desaturation method is that the resulting image can often look flat and lifeless. The image lacks depth and texture. To me, one of the most interesting things about this particular image is the texture of the skin, and I want to emphasize it. The Calculations tool is one great way to do it.

Start with your color image, and then go to the Image menu and choose "Calculations..." You'll see the following dialog box, and your image will turn black and white instantly.

You'll probably want to play with the settings to get it right. The Calculations tool allows you to combine the red, green and blue channels of your image into a black and white image. Remember, each of the source channels actually looks like a black and white version of your photo, because it represents only the luminosity values of red, green or blue in that image's pixels.

As you can see, the Calculations dialog allows you to choose which channels to combine and how to combine them. You have a choice of blending your red, green, blue or grey channels together. It would be impossible for me to explain each and every combination and blending mode, because there are hundreds of possible combinations. However, I find the above combination of channels works well in most situations in which you wish to create a textured image. I set the blending mode to "Overlay" or "Multiply" and then decide which one I like better. I set the opacity to around 30%. Higher values of opacity cause "Source 2" to have a greater effect on the finished image. Lower opacity values cause "Source 2" to have a lesser effect.

The best way to learn what works for you is to experiment with the different settings. Don't be afraid to try different combinations of channels, different blending modes, and different opacity levels to find out what works best for your particular image.

When you've found the combination that works for your image, set the Result to "New Document" and click OK.

You're almost done. What you've got on your screen is a luminosity channel. You have to convert it to greyscale before you can continue working on it like a normal image. Go to the Image menu and select "Mode" and then "Grayscale." You can go back to Image -> Mode and choose "RGB Color" if you wish to do anything else to it that involves color, like tinting it. After you've changed the mode, you may now save your black and white conversion just like any other digital photo.

As you can see, the Calculations method is a little more complicated than straight desaturation. However, I think you'll find the results are rewarding. I hope you enjoyed this tutorial. Happy shooting!

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LetoLuver917 Featured By Owner Aug 23, 2010   Photographer
I love this! Thanks so much!
Marie-Aude Featured By Owner Dec 7, 2007
Thanks a lot. I stumbled upon this method today, and I really like it !
I was using the channel mixer, but I prefer the results of this one
S-t-r-a-n-g-e Featured By Owner Aug 27, 2006
Nice tutorial, but i like another way for B&W converting. It's a channel mixer..
I find it more specific for every channel i want to add or to remove from the picture..
And your sample picture too good for every method of conversion !
ZenithBlur Featured By Owner Aug 27, 2006
wonderful tut. thanks for sharing it =D
I'll be sure to use it
TanyaSimoneSimpson Featured By Owner Aug 27, 2006
This is a really great tutorial! Have you also posted it in the tutorial section? If you have an you'd like to share it some more, drop a note to *PhotoLust cause I'm always on the hunt for great tutorials to feature there (and you'll be given credit, of course).
krash Featured By Owner Aug 24, 2006  Professional Photographer
You should turn this into a PDF and upload it as a deviation.
Stalker72 Featured By Owner Jan 29, 2006
thanks for this tutorial, I have a lot of PS to learn:D
equivoque Featured By Owner Nov 28, 2005
this is awesome! power retouch also has plugins to offer a variety of bw (ilford, agfa, etc.).
kidscruff Featured By Owner Oct 24, 2005
thanxs for the tip and for sharing-i'l try it out!
kkart Featured By Owner Oct 3, 2005  Professional Photographer
I have to admit, I have never heard of this method before either and have bookmarked it.....that has some serious impact....almost film like really. I will try this. Thanks for sharing!
FloatingAiko Featured By Owner Jun 26, 2005
Thank you very much for new method!
I always used curves and sometimes levels, but your method offers some more abilities.
LenzFrenzy Featured By Owner Jun 20, 2005
that is absolutely very helpful! I thank thee grately
konador Featured By Owner Jun 14, 2005   Photographer
Thanks for the info - very useful :)
However it should be noted that it is always best to convert back to RGB when saving, not stay in greyscale, as some applications treat greyscale images differently to RGB and they may be shown as corrupt files or something when uploaded to the internet in some circumstances.
x-ray-cat Featured By Owner Jun 11, 2005
very usefull thanks
kinslow Featured By Owner Jun 5, 2005  Professional Digital Artist
thanks and by that I mean THANKS
backdoor-man Featured By Owner May 30, 2005
Thanks for sharing :yum:
icedsmurf Featured By Owner May 28, 2005  Hobbyist General Artist
this is a nice technique, i have a few different ways of going about it for the certain effect i want to achieve though.
scy00013 Featured By Owner May 24, 2005
Hi Kevin! Thanx for this one, it's adding some new input for b&w-conversion :-)
LenzFrenzy Featured By Owner May 24, 2005
amazing! im going to use this! I definately am! thanks a lot for that helpful tutorial!
LeTHaL-1- Featured By Owner May 20, 2005
nice one, i usually use this one or the channel mixer one depending on what im going for
Shurakai-Zero Featured By Owner May 19, 2005
Another interesting application of this is to take your original colour image, convert it to Lab, then swap your newly-created B&W image for the Luminosity channel in the colour image. Makes for a striking colour portrait without introducing any significant colour casts.
skinniouschinnious Featured By Owner May 19, 2005   Interface Designer
Meh... the calculations tool is kinda useless in my experience. And it's not editable afterwards is it? TO make an image black and white like this, wouldn't it make more sense to use the Channel Mixer and click Monochrome and make the Blue channel 100% with the others at 0%. If you did that as an Adjustment layer it would be editable afterwards.

Seems less complicated than this too. :shrug: I guess there are about 1000 different ways to make an image black and white though.
AlanRalph Featured By Owner Aug 27, 2006  Professional General Artist
This is the great thing about Photoshop, though... there are often several ways of doing certain tasks such as B&W conversion, from the quick-and-dirty to the more precise and controlled. :) Bear in mind, the Calculations tool has been there since way back, whilst the Channel Mixed adjustment layer is a more recent addition.
superkev Featured By Owner May 19, 2005  Professional Photographer
it's true. there are so many different ways to do it. this is just one tool, and it works perfectly only in a few situations. it's kinda like that weird thing in your toolbox that's used for cutting oddly-shaped pieces of wood. it's not often you need to cut an oddly-shaped piece of wood, but when you do, it's exactly what you need. the blue channel mix doesn't quite give the same effect. it's close, but not perfect.
evilclowness Featured By Owner May 19, 2005
think i'll give it a shot... thanks for the tip! :D
Nichols Featured By Owner May 11, 2005   Photographer
Thanks very much for that, I wasn't even aware of a Calculations method, I'm very grateful. Good tutorial, with excellent examples! :)
S2Photos Featured By Owner May 10, 2005  Hobbyist Photographer
marvelous tut. thanks a bunch!
morettina Featured By Owner May 10, 2005
thank you, I tried this method and I like it! :D
taoge Featured By Owner May 10, 2005
very very useful :D
mental Featured By Owner May 9, 2005  Professional Photographer
Tres cool.

Adds this to his brain.
Moonbeam13 Featured By Owner May 9, 2005  Hobbyist Photographer
:clap: Very awesome :)
Sheik17 Featured By Owner May 8, 2005
an other way is to convert you picture in lab color,
then delete the channel b
and the channel alpha 2.
when done change your mode to grayscale.

thats will give you the best result.
In-Apt Featured By Owner May 8, 2005
Simple, yet interesting.

I shall have to try this method, I had never used calculations before! :nod:
Dark-Renaissance Featured By Owner May 8, 2005  Hobbyist Photographer
I've actually had better results more often with the gradiant method of conversion to B&W. Its always nice though to know other things, and it seems this method is really good for texture. At least I'll have a choice between Gradiant and Calculations now!
pinkcookie Featured By Owner May 8, 2005
firstly, thanks for putting in the time and effort to make this for us :aww:
its a wonderfuly written tutorial and im deffently going to try to use this method in the future :nod:

Freaks-GeeksAndFlesh Featured By Owner May 8, 2005
Very cool...
CathieHeart Featured By Owner May 8, 2005  Professional Interface Designer
Thank you so much Kev, its radically different from how I do mine, I do Lab conversion and then choose the lightness channel, then change the mode to greyscale, which means that it keeps the lightness and depths of the photo in colour but just makes it b/w. However with this calculations method so many more interesting options are open. Thank you again :excited: :D
Killshi7 Featured By Owner May 8, 2005   Writer
I still perfer the method of using the Gradient Adjustment layer mixed with the LAB method of desaturation.
superkev Featured By Owner May 8, 2005  Professional Photographer
methods like this one are for specialty purposes only. usually i use a channel mixer adjustment layer. but if you want texture, this is the way to go :)
SilentMYSTIQUE Featured By Owner May 8, 2005   Photographer
I usually use the channel mixer to convert to B&W but it's always great to know new ways of doing things in Photoshop, expand the ole horizons so thanks for this, I'll try it out next image! :D
bule Featured By Owner May 8, 2005   Photographer
How do you use the channel mixer to get the b/w you want?
superkev Featured By Owner May 8, 2005  Professional Photographer
add a channel mixer adjustment layer on top of your color image layer, and click on the "monochrome" checkbox. then you can adjust the red, green and blue sliders to determine the percentage that each channel will each contribute to the luminosity of the resulting greyscale image. for the resulting image to have the same exposure as the original color image, the numbers should all add up to 100%. for light colored skin, it looks nice to have a higher mix of red channel. blue and green contain the texture. i usually recommend a mix of red=60, blue=20, green=20 for the typical portrait. adjust as needed :)
vulpul Featured By Owner May 20, 2005  Professional General Artist
fine stuff! :) I use often the "fast way" by adding an adjustment layer (hue/saturation) right over the colour image layer and desaturate it, but on the layer's blend mode I choose "saturation". It transfers the "no saturation" to the colours allowing the natural tonal contrast of the colours.
It's a good way to try all these methods on a coloured squares grid with the basic colours to see the tuning level of each method. :nod:
superkev Featured By Owner May 20, 2005  Professional Photographer
i'll have to try that sometime. thanks! :)
Killshi7 Featured By Owner May 8, 2005   Writer
I actually gave this a try, it's quite similar to the channel mixer, but it does have it's own individual style of desaturating things. I'm gonna try it out on my next b/w.

monkstar Featured By Owner May 7, 2005   Photographer
cool, never knew it can be done this way before :)
The-I-Craze Featured By Owner Jan 24, 2006
OMG!! I love this. its one of the most creative ways ive seen for a while.
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