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Color photographs into b&w the right way, and more ...

Submitted by boondock_saint on 2006-02-18

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As someone who enjoys black and white photography I will be the first to say that nothing can ever replace the look of a Kodak Tri-X negative enlarged on some glossy fiber paper, but how many of us have the opportunity to work in a darkroom and play around in dektol all day?

You could always fall back on CN (or C-41 process) film which is a B&W film that can be developed at any 1 hour photo, but I find this too be too expensive and often produces less than desirable results such as color casts and duotone images. It's an approximation of B&W at best and unless you are using an enlarger to make prints you will not even approximate the quality of a true B&W print.

Let us not forget digital cameras in this as well. Serious digital SLR cameras are becoming more and more affordable and if you enjoy photography, there is no reason not to have one. While some digital cameras are capable of capturing B&W images (mine also allows me to "use" or rather emulate filters) I don't see any reason to do this. You will never produce a true black and white print with the information you've just captured so why limit yourself?

Working as a graphic designer and attending school to finish my B.S. in Graphic Communications means I deal with digital images (usually in Photoshop) 8 to 10 hours a day, and a question regarding a black and white images in the photography forum prompted me to share some of this knowledge.

I think I already summed up why not to shoot B&W unless you're shooting *real* B&W that you will print on an enlarger, so let's move on and talk about what you can do with those color images you have.

Images on your computer all are made up of red, green and blue colors represented at different levels (28 = 256 levels of each to be exact). A grayscale images is simply 256 levels of luminosity and no color. This is bad because what happens when you have the a color image with similar tone values? You lose the information as illustrated below.

Red, green and blue dots
Red, green and blue dots desaturated

I think this example serves very to show just how much information is lost by simply removing the color, and what kind of effect his can have on your image. This tremendous loss of information is usually not as noticeable because most images are not as flat in color and tone. I call this a loss of information because what we want to do when converting to a black and white image is to discard information, not simply lose it. I generally like to choose what part of my image I want to discard.

The most obvious tools in Photoshop are "Grayscale mode" and the "Hue/Saturation" command found in the Image -> Adjustments menu. When applying the Hue/Saturation command, move the the Saturation (middle) slider all the way to the left. This will take all the saturation out of the color leaving you with a black and white image. Both of these are a very quick and easy to use but they simply throw away information often leaving the image looking rather dull as shown above.

Prior to writing this tutorial I shot this Image of some flowers in my house and in retrospect, it is probably the most terrible image I could have picked for this, but just bear with me.

My lame image but at least it contains some red, green and little bit of yellow.

Here is what the image looks like when converted to B&W using the more common methods:

Converted to B&W using Hue/Saturation
Converted to B&W using Grayscale mode

You can see that we have almost completely lost the red of the flower that was standing out in the original image. If you think that is how it's supposed to be, well I don't believe it is. Professional photographers use an array filters to block out light and thereby allow certain parts of the image to appear more luminous than others, all depending on what they want. A much cheaper way of doing this is to use the "Channel Mixer" tool in Photoshop.

The Channel Mixer can be found in the Images -> Adjustments menu but here I want to touch on another important topic. Fill and Adjustment Layers. The "New Fill / Adjustment Layer" button can be found at the bottom of the Layers palette. If you do not have layers open go to Windows -> Layers to open it. I spend quite a bit of time in the computer labs at school and I often see people make the mistake of editing their files irreparably. Sadly even some of my co-workers are guilty of this.

The button highlighted on the left will open a menu where you can choose most of the tools that are available to you in the Image -> Adjustments menu. You can adjust your levels, curves colors, brightness, contrast and many other image commands here without ever altering the original image. You can also come back to the adjustment layer and double click it to pull up the information it contains, and change it if you need to. Fill and Adjustment will be available in any contemporary version of Photoshop. If you have Photoshop CS or CS 2 you can also use this in conjunction with the "Layer Comps" tool.
The Layer Comps tool allows you to save the current arrangement of layers as well as the visibility of layers. You can turn layers off and on, save your layer comp and compare it to another. This tool becomes invaluable once you start getting used to making use of it. While it is most useful with files that have upwards of 20 layers you can use it with any amount. If you have Photoshop CS or CS 2 you can use layer comps to display your image with any combination of Channel Mixer Adjustment Layers in this case. This is great if you aren't completely sure what you want in your image or are just starting to use the tool.

I hope that you will use what I explained above and never have to wish again that you had saved another copy of the file before you made the adjustments. Keep in mind that you will have to save the image as a PSD file which noticeably larger in size than its jpeg version would be. If it's a pic you like and you think you will make more adjustments to it in the future, go ahead and save it as a PSD, layers and all.

Using the Channel Mixer will take some practice. What you have to keep in mind though is that you can control a black and white image with colors, you just have to know how to apply them. I don't want to get too deep into color theory, but essentially this is how it works: to increase contrast in a particular area you will want to choose a filter color which is complimentary to that area's color. If you are converting the image to black and white, make sure the Monochrome box is checked. Getting an image to look good will take some adjusting of the sliders for each color because in digital image processing the filters affect all of the RGB channels. Generally you will want to make your sliders add up to a 100% but sometimes going above and below that can produce very nice results. You can also move the sliders into the negative numbers but be careful not to push the image too far. There is one more slider, called the "Constant" in Photoshop CS 2, which basically affects the overall brightness. Yes there are many variables involved in using the Channel Mixer but once you have it down, you will never go back to a simple grayscale image.

Here are a few example adjustments I made to the original - the best way to get familar with the Channel Mixer and what may work well for your image is to use each of the colors at a 100% as shown in the first three images:

In this example, I used the following settings:

Red: 100%

Green: 0%

Blue: 0%

Constant: 0%

Red: 0

Green: 100

Blue: 0

Constant: 0

Red: 0

Green: 0

Blue: 100

Constant: 0

Red: 144

Green: -46

Blue: -24

Constant: +12

Red: 138

Green: -86

Blue: +76

Constant: -10

It is now just before 4:00 am so I will conclude this article. I hope you enjoyed reading it as much as I enjoyed writing it - and maybe you even learned something. If you have any more questions regarding Photoshop, feel free to PM me.


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2 Comments CommentAdd a Comment

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5 out of 5 stars Great article. I can put the channel mixer and layer comp techniques to use immediately. Thanks so much for taking the time to write it.
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Thank you for the early morning input!

Already tried the techniques and they work great!

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