HDR Basics

HDR (same as HDRI, High Dynamic Range Imaging) is a technique that image editors can implement to expand the depth and range of light in a photo. Flat and dark areas of the image are granted more exposure, while the bright parts, that already exist in the image, are granted more contrast. For example, sites of sunsets that naturally silhouette a foreground can be balanced compositionally, so that the foreground and sunset-sky-background are in harmony. The magical effect can look surreal if brought to the HDR extreme, but it can also be a useful method to subtly tame high-contrast photos. The light in HDR images seems to glow and the shadows dip into black satin.

Pic. 1 (Extreme HDR) by David Morris _______Pic. 2 (Subtle HDR) by Erik Söderström

HDR photographs are generally achieved by capturing multiple standard photographs with any camera that allows manual over-/under-exposures. The next step is to use exposure bracketing, and then merge the range of under- and over-exposed photos into one HDR image. If you do not have a camera with these capabilities do not despair. Photoshop provides various methods to imitate the effect. I’ve briefly outlined a couple of these below:

A) Create a few different digital images from your original and save them separately. Then just merge them together into one. (see blog: “Double Exposures“)

B) Re-work just one image, by selecting it’s light-varying parts and modifying them via “Exposure” and “Saturation”. I’ll walk you through this below:

First, use the “Lasso Tool” and/or “Magic Wand Tool” to trace around and/or select the darkest, least contrasting section of your image. Perhaps it, in part, fades into the light? Well, in that case, utilize your “Define Edge” button (to the upper, left) and decide on your fade range. Once you have that darkest area (or areas) selected you can go to: Layer ->New Adjustment Layer -> Exposure. You’ll want to slightly bring up the 1st level “Exposure”, and slide “Gamma Correction” towards the right to provide depth to your new brightness level. You may also consider color-saturating that selection: (Layer -> New Adjustment Layer -> Saturation). Play with the “Preview” check box (lower, right of adjustment windows) to make sure the selected area’s border doesn’t clash harshly against its neighboring unselected areas.

Second, use the “Lasso Tool” and/or “Magic Wand Tool” again to grab the brightest and most exposed areas of your image. Use that “Define Edge” button here as well, if needed. Adjust the Exposure levels again. However, bring the Exposure level down, the “Offset” down to just about -0.0010, and slide the Gamma Correction level to the right a bit to again, to add more depth.

Of course, the key to this method is trial by error and just playing around with the various, selected areas. I highly recommend saving each selected area as you go. You will likely want to re-adjust levels in your attempt to provide your pseudo-HDR rendering the best balance possible. (Select ->Save -> name your selection, and to retrieve it: Select -> Load -> drop box with your titled selections)