My Image Torture Test
April 5, 2018
Watching a person’s eyes as they examine a group of framed prints can be revealing. Their eyes linger on images of interest, and glide right past images they find less appealing. Many factors influence the stopping power of an image, of course, but one attribute shared by strong images that is absent in neglected images is an appealing balance of lights and darks, what Japanese artists call notan. An image that is overall too dark feels “heavy” and is easily ignored.
It can be difficult to determine the best overall density for an image displayed on your monitor. A wide variety of exposures can all look pretty good. An image can seem acceptable on a monitor and still feel too dark when printed.
This problem is particularly acute when editing night images. After all, it was dark out there, and your natural instinct is to create a dark print to capture that nighttime feel. Unfortunately, a print that is literally as dark as what you saw, particularly before your eyes became dark-adapted, is likely to fail as an aesthetic object. Make the print too light, however, and it can look like a daylight image with lots of white dots in the sky. Striking the right balance can be hard. The most common mistake is making the print too dark.
You could just make a series of test prints, of course, but that wastes time, money, and materials. There’s a better solution.
First, set the background of your editing space to white. In Lightroom Classic, in the Library module, display an image in Loupe view (press the spacebar or click the Loupe view icon in the Toolbar), then right-click on the pasteboard outside the image area and choose white. Or open Preferences, select the Interface tab, and choose white as the Fill Color for the Main Window. Now, at the top of the Navigator panel (top-left of your screen), open the drop-down menu and choose 1:16, as shown in figure 1. That will display the image as a thumbnail on a glaring white background. Examine the thumbnail carefully. Can you still “read” the image? Can you still pick out details in the shadows, or do they seem to have merged together into one inky-dark mass?
If the image feels too dark, open it in the Develop module (still viewing it at 1:16) and use the Exposure slider in the Basic panel to lighten the image. Often a change of .3 to .5 stops is all that is required.
This image torture test relies on an optical illusion called simultaneous contrast. If you place a particular tone, let’s say a middle gray, against a dark background, it will look lighter. If you place the same tone against a white background, it will look darker.
Don’t believe me? Take a look at figure 2. The thin vertical rectangle is an absolutely uniform shade of gray from top to bottom, yet it looks like it contains a gradient from dark at the top to light on the bottom because the background contains a real (but inverted) gradient from light at the top to dark on the bottom. Now look at figure 3, which shows the same thin rectangle set against a pure white background. No gradient is apparent.
Figures 4 and 5 show two versions of the same image. Figure 5 is a half-stop darker than figure 4. When viewed as images measuring 900 pixels on the long dimension, they both look pretty good. Now examine figures 6 and 7, which show the same images 300 pixels wide, set against a pure white field. Now the darker image, at least to my eyes, simply looks too dark.
Once you’ve adjusted the image until the thumbnail version looks right, make a test print. As a final check, examine the print under different intensities of light at various places in your home. If it only looks good under a track light, it’s still too dark. Most likely you’ll find that if the image looks good as a thumbnail on a white background, it will look spectacular as a print.
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