D-Stretch in Photoshop
D-Stretch is an image enhancement technique that I first learned about when I saw it applied to prehistoric pictographs. There is a plugin to the software ImageJ which will handle an image and produce a d-stretched version of it that can be found here . However, as someone who is comfortable working with digital images in Photoshop, I wondered if there was a way to replicate the effect in house. Here I present to you what I learned, and some thoughts on the process. Let's start with a photograph of the Horned Dog, a particularly well preserved red ocre pictograph in Tennessee. The photograph was shot as raw, and processed for optimal display. White balance was adjusted based on the scale present in the image. We will want to convert the image to the Lab color space to proceed (Image > Mode > Lab Color). Check your channels tab, you should see these three channels present: Lightness, A, and B. We'll be individually adjusting these channels so keep this handy.