Density in a Photo


Today’s Question: A couple of days ago you gave the following example to a question about opacity of layers:

“…a quick way to increase density in an image is to add an adjustment layer without actually making any changes to the default settings for the adjustment layer. Then change the blend mode for the adjustment layer to Multiply”.

I’ve been wondering what you mean by “increasing the density” of an image. That terminology never comes up when discussing processing with Lightroom. What would the equivalent treatment be if working solely in Lightroom?

Tim’s Answer: In large part I would say that my use of the term “density” in the context quoted above is a product of having started my photographic adventures in the world of film photography (and specifically, slide film photography). With a slide, there is a need to ensure an adequate degree of density in the information captured in the emulsion. In other words, a completely clear slide (with no density) has no useful information, while a properly exposed slide has “good” density. This relates, in the context of slide film, to the density of the dyes present in the slide film, which form the actual image you can see.

When I refer to density in a photographic image, I’m referring to the same basic concept in terms of information being present in the photo. In other words, in a very basic way I’m talking about darkening the exposure to increase the density of information, as long as we think about that information in terms of adding darkness. In other words, the term density in this context makes more sense when thinking of a photo printed on paper rather than an image projected on a computer display.

Lightroom does not include blend modes, and so you can’t use the “trick” of using the Multiply blend mode to darken the exposure (increase density) or the Screen blend mode to brighten exposure (reduce density). However, you can achieve a reasonably similar result through the use of the basic tonal adjustments.

I would start with the Exposure slider to apply a basic overall adjustment to the tonality in the photo. You can also fine-tune the effect with the Shadows and Highlights sliders to adjust the overall appearance of detail in the image. You can even make use of the Whites and Blacks sliders as needed to fine-tune the brightest and darkest values in the photo.

Ultimately, besides illustrating the potential pitfalls of applying terms from film photography to digital photo processing, I think this topic underscores the importance of understanding your tools and focusing on the photo. In other words, there are many different tools available in many different software applications, and I wouldn’t get too caught up about trying to translate the tools from one application into another. Instead, I encourage you to focus on the photo you are working on, think about what will make that photo look its best, and then use the tools in the software you’ve chosen to work toward that result.