Controlling Dynamic Range
I have a love hate relationship with the term hdr. While I like to use it when the scene demands it, I hate talking about it because it has built up such a negative reaction that’s mostly associated with the images, in my opinion only, are over processed and often silly looking. At the same time, the realistic hdr images go unnoticed as a regular photograph. This alone gives the term hdr an unfair review as all being cartoony.
I realize this topic has been abused to no end but for those not familiar, the original purpose of hdr (or high dynamic range) was to deal with the range of light that the eye can see but the camera can not. Our eyes can adjust for high contrast scenes from the very bright to the very dark. The technology in today’s cameras can’t do that yet forcing us to make a creative decision to either silhouette the shadows or over expose and blow out the highlights. In these high contrast scenes, the camera can not physically record what the eye sees.
Today’s Image – South Rim of the Grand Canyon
In late October, I went on a trip through the American Southwest to experience first hand the landscape that has become so famous among photographers. My first night at the Grand Canyon was a good example of the vast range of light. With bright white snow at my feet, a dark and deep canyon in the distance and a bright setting sun behind a bank of clouds, the scene was simply more then a camera could handle in a single exposure without compromises.
Before and After
The technical difficulties are apparent. As a photographer with today’s limitations, you are forced to make an exposure decision. Make one area too dark or one area too bright. To record as much details as I could, I made 3 images from this location with the intention of using the best from each.
The following image shows the before and after. Use the slider to transition between them. The photo on the right side is the compromise exposing for the canyon which makes the top left very bright. The left side is what a little bit of blending 3 images together can accomplish. I can assure you that to the eye, all areas including the colors of sunset as well as the canyon floor were visible.
Why start with the brighter image? If we are familiar with the concept of exposing to the right — to capture the highest quality of detail with the least amount of noise, we make the image brighter than it should be without clipping the highlights. When you get back to the computer, you darken the image back down to where it should be and the areas that are blown out and can not be recovered, are merged in from the other darker exposures. There are several different ways to do this so I’ll save the actual steps for a future post.
The idea behind this entire post got stuck in my head while preparing an artists statement. Hardware manufactures are not the be all and end all so let’s not look down on post processing as a whole. Software is created to compensate for what hardware still can’t do. Don’t let technology be your handcuffs.