While out at a pond with my family, I was intrigued by all the life and activity just below the surface of the water around this inert stump but I was being called to join the rest of the people I was with so I didn’t take the time to put a polarizer on the lens. As is often the case, what I thought would be a “good enough” picture just wasn’t after I uploaded the day’s images to my computer and took a closer look. So I decided to do some tweaking.
Interesting, eh? The way I got the details of what was under the reflective surface of the pond was by applying the high dynamic range imaging (HDRI) techniques to a single image. Usually you use this technique quite deliberately after careful planning that involves putting your camera on a tripod, taking several shots at different shutter speeds so you properly expose both details in the highlights and shadows (and everything in between), and then feed all the images through a special computer program. When you apply HDRI techniques to a single source image, the resulting HDRI image is sometimes referred to as an FHDRI, or Fake High Dynamic Range Image.
Here’s how you can do the very same thing I did to some old images you might have in the archives…
- Find an image you shot in the RAW format that has a lot of contrast. If your camera is able to save RAW images, you really should be shooting RAW images all the time in spite of the large file size — the flexibility in editing RAW images truly outweighs any disk space-saving benefits of shooting in JPEG, for example.
- Save the image as a TIFF.
- Move the exposure adjustment slider to the -2 EV (exposure value) setting. Save that picture with a different filename than the first (I suggest adding “-2” to the end).
- Move the exposure adjustment slider to the +2 EV (exposure value) setting. Save that picture with a different filename than the first (I suggest adding “+2” to the end).
- If you don’t already have a program to generate HDRI images and to tonemap them, I recommend Luminance HDR because it’s free and it does a pretty good job.
- Open the program and follow instructions. I suggest you just go with the default setting to begin with and only change them if things don’t work out to your satisfaction. Note: Whether you use Luminance HDR or another program, having used three (or more!) files from the same exposure might fool it. When the files are loaded into the program, the EV value of each file will be shown beside the filename. If all EV numbers are the same, then for your “-2” file subtract 2.0 from the value displayed and enter it as the value. Same thing goes for your “+2” file but this time add 2.0 to the value displayed and enter it as the value.
- Click through until you get to a prompt that says something like “Generate HDRI”… click that button!
- It might take a couple of minutes for the HDR image to be generated but when it is, save it. Don’t worry if the resulting image looks flat and crummy… we’re only just getting started!
- Look for the button that says something like “Tonemap the Image”. A new window will open, and you’ll have a whole new set of confusing controls to deal with.
- If your original image was large, then look for the “result size” or “output size” selector and choose something smaller than the original dimensions of your file. Luminance HDR doesn’t have a real-time preview so when you change a setting, nothing happens on-screen until you hit the “tonemap” button on the bottom. You’ll probably have to try a bunch of different settings before you arrive at something you’ll be really happy with and large files can take a lot of time for your computer to process. I suggest you first set the “result size” to something small, like something in the neighbourhood of 500 pixels.
- After you get what looks like something great at 500 pixels, increase the result size to the max! If you like what you got, save that image!
- Play around with the different settings, starting with the “pregamma” setting, which basically controls brightness. I suggest that you try adjusting the pregamma first of all to zero in on the general range you’ll be working in and then try the other adjustments afterwards to really bring out the character you’re looking for.
- If you got images that just don’t show any signs of promise, try a different “Operator”, which can be found in the upper left quarter of the screen. Each operator uses a different mathematical formula to arrive at a final image and has its own particular look. If I remember correctly, I used the Mantiuk operator for the two FHDRIs on this page. Once you change operators, you’ll have to start trying different settings all over again and different operators have different settings to adjust. The one they all have in common is the “pregamma” setting.
Here’s the final image…
So, there you have it. Run out now and make your own HDRIs and FHDRIs. Don’t forget to post the results and let me know about them!
See you next week.