Shedding Light on Black and White Part 3: The Digital Conversion


A comparison between the way film-based cameras and digital cameras capture spectral information and transpose that information into black and white images.

Photography is all about Light. The more we understand about the way light behaves, the better we will understand how to capture it, edit  it, and render it in both display and printed form. 

Sorry for the delay in posting this final segment, I just returned from a month-long trek through southern Europe capturing about a zillion images from rich, cultural cities.

Original sRGB Color Camera Capture

Original sRGB Color Camera Capture

This color image of Frauenkirche Cathedral was captured in Dresden Germany. In this session we’ll look into how to interpret your color pictures into rich black and white images.

Each color is converted to a range of gray tones. The trick is to analyze each image for its color content and the relative importance of that color in the grayscale interpretation. 

As with most other issues in photo reproduction, restraint is the key. Considering the interpretive freedom that digital color conversion affords, digital black and white images can actually provide superior tonal transitions to dedicated grayscale film emulsion captures. 

Color vs Monochrome ColorChecker Captures

Color vs Monochrome ColorChecker Captures

First, realize that not all colors are created equal. By this I mean that solid yellow should always produce a lighter shade of gray than red or blue. Probably the best way to understand these tonal values is to shoot an x-rite ColorChecker passport chart using your camera’s Daylight white balance setting (obviously under daylight conditions).

Custom Value Assignments vs Default Grayscale Values

Default Color>Grayscale Value Table

When this RGB file is then converted to Grayscale (from the Image/Mode menu in Photoshop), the relative gray values of the primary and secondary colors can be observed. As each solid color value is revealed, keep these general “solid” values in mind as you build your Custom conversion palette. 

Photoshop provides a powerful color-to-black-and-white conversion tool that allows you to produce a custom table for your individual camera sensor (Image/Adjustments/Black & White…). The default settings for this tool shouldn’t be trusted for “fit” anymore than a one-size-fits-all dress or suit. Use a Monochrome capture of your X-rite colorchecker to visually balance the mix of color channel values to actual grayscale values. 

But even this custom setup shouldn’t necessarily be your ultimate grayscale conversion process. Over time and trial and error, you can develop your personal preference settings.

Custom Color>Grayscale Value Table

Custom Color>Grayscale Value Table

This chart image can be used to fine-tune your grayscale values. Just as Kodak, Ilford, Agfa, and other black and white films provided a color/tone bias, you too can establish your own “Signature” black and white conversion look. Every camera manufacturer’s image sensor records these colors uniquely. With a little experimentation, you can develop a very rich and powerful conversion table to interpret your own camera’s image sensor algorithm.

frauenkirche-dresden-Gray1

Saturation Values Removed

Default Grayscale Conversion Table Results

If you choose to convert your color image to Grayscale (Image/Mode/Grayscale), or simply remove all Saturation values (Image/Adjustments/Hue/Saturation…), the resulting default gray equivalent values will not accurately translate into the proper grayscale values. Never again settle for a lifeless, one-size-fits-all black and white conversion. Monochromatic images are incredible powerful visual statements. Remember, black and white images fuel the imagination in a way that color images simply cannot. Make your black and whites demand the attention of your audience and thus deliver the full impact of your personal interpretation.

That’s the way I sees it. Take some time to experiment with these conversion tools. Shoot some images of diverse color themes and develop your own “signature” conversion table. This is very powerful stuff. Once again, the more you learn about light, the better your photography will turn out. Get bright about light and the dividends will pay off big time.

If you learn a little something from this blog, I seriously suggest that you take the opportunity to learn more about the basics of light and color from my online video series entitled the “Gotta Know Videos: Part One- Light and Color.” http://gottaknowvideos.com

Until next time, this is Herb Paynter

hpaynter@imageprep.net

About Herb Paynter

I'm an author, photographer, lithographer, color consultant, and speaker living in Sarasota, Fl. I've been in the color game for more years than I care to admit. In that time I have picked up a lot of insights and experience that I like to share.
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One Response to Shedding Light on Black and White Part 3: The Digital Conversion

  1. ekhphoto says:

    Good post, Herb. Now if you could only tell me how to keep my Z3200 from flooding magenta into (almost all) skin tones, you’d have something!

    Seriously, I’m sure many will appreciate your approach to bw conversion in camera. For those who like to tinker with BW conversion, there are at least 4 methods readily available inside Photoshop, and if that’s not enough, I’ve had good luck with Perfect B&W from OnOne software (here’s a sample: http://ekhphoto.photoshelter.com/gallery-image/Geology-and-Water/G0000ofeCrRCqRfM/I0000GwJZ2V9nX6U)

    Photo Ninja, nee noise ninja, has a very smooth routine for adjusting BW images, then toning them. There are several examples in the “geology” gallery of my site at http://hatchphotoartistry.com.

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