Evaluating Black and White Tones


Today’s Question: Thank you for your video on black and white conversions using Lightroom Classic (https://youtu.be/mLTl1VlRoqc). When you have finished your black and white adjustments, do you have a test to determine the distribution of tones across the image?

Tim’s Quick Answer: The primary approach I take to evaluating the tonal distribution in a black and white image is to first evaluate the clipping preview display and then simply view the overall image on a calibrated display. However, you could also measure tonal values throughout the image and review the histogram for the finished image as well.

More Detail: Many photographers are likely familiar with the “Zone System”, where a full range of tonal values from black to white is divided into eleven zones. It is somewhat common for photographers who create black & white images to try to ensure that all eleven zones are reflected in the final image.

Some software actually presents information about the tonal values in an image using the Zone System. For example, Silver Efex Pro, which is part of the Nik Collection by DxO, includes the Zone System as part of the histogram display. You can hover over a button for each zone to see an overlay on the image showing which areas represent that zone.

Lightroom Classic does not include such a feature, however. You can still use some techniques for evaluating the tonal values within the image.

To begin with, while adjusting the overall tone for a black and white photo in Lightroom Classic I recommend using the clipping preview display, which is accessed by holding the Alt/Option key while adjusting most of the tonal value sliders. This enables you to see exactly where in the image detail is being lost due to clipping.

You can also simply evaluate the image on the screen, provided you’re using a calibrated display. If you’re not already calibrating your monitor display, I highly recommend doing so with a package that includes a colorimeter device, such as the Calibrite ColorChecker Display (https://timgrey.me/calibrite).

The histogram can also be used to get a reasonable sense of the overall distribution of tonal values within an image. This isn’t an especially precise approach, but it does provide some sense of the tonal values represented within the image.

Taking the histogram a step further, you can actually evaluate the tonal value for individual pixel areas within the image by using the histogram display in the Develop module within Lightroom Classic. Simply hover your mouse over the image and below the histogram display at the top of the right panel in the Develop module you will see the values for red, green, and blue presented as percentages.

For a black and white image all three values will be the same, so you can simply focus on one of the three. With this display a value of 0% represents pure black, 100% represents pure white, and of course the values in between represent shades of gray.

You can view a recording of my webinar presentation on “Black & White with Lightroom Classic” on my YouTube channel here: