This past week in class saw our introduction to shooting HDR images. HDR, which stands for “high dynamic range,” is a method used mainly in place of flash to add detail in areas that would typically be obscured by normal exposures.
The basic idea with HDR is that you bracket a set of exposures (shooting the same image at different exposures, usually in even intervals), which in this case is a set ranging from two stops under to two stops over exposed in one stop intervals. That way you have full detail, or at least increased, shadow and highlight detail. This technique left me with five separate images.
Although there are a few ways to do so, in class we used Photoshop to merge the images. The two images I worked on are attached below, with three different versions of each:
- The “to meter” exposure that is unedited
- An unedited HDR image
- An edited version of the HDR
The results can be pretty impressive, however this method isn’t without drawbacks. Firstly, you can often times end up with a slight color distortion that could be described as making the image look dirty or grimy, along with other more general color shifts. In this case the images being monochrome rather than color, this more or less removed that issue from as prominent a distraction. Another tell-tale sign of over-done HDR are halos, or greyish white hazes that seem to cling to the edges of objects, largely to do with the degree of contrast or sharpness done in post production. These hazes will have an appearance that resembles a “high pass” layer used to sharpen the image when the pixel rate is set to high, for reference. The final main drawback is the general flatness that the images tend to have when unedited. In the case of the my own files, I used Camera Raw filters in Photoshop to reintroduce a more photographic appearance.
These issues mainly describe instances where the method is abused, but HDR isn’t without its pros. If done properly you will end up with an image that has greater perceived sharpness and dynamic range, as well as the ability to have balance that a single, straight photograph can’t have, like detail outside of a sunny window, as well as in the shadows. The image you are left with ultimately resembles what your eyes would see in a space, rather than a camera.