You might assume the answer is always yes, but I’m finding that the answer is maybe, maybe not. With the cold and rainy weather, I’ve spent more time inside working on editing or re-editing some old images, and I’ve found a surprise or two when it comes the need for three or more images to create an HDR image. In past articles I’ve talked about the need for HDR when the dynamic range of a scene exceeds the sensor’s capability to record it. I’ve also tried to show the look of Lightroom and Photomatix HDR images, both when the scene is within the sensor’s range and when it exceeds it. Here I’ll try to show if and when you need multiple brackets to create an HDR.
Part of the reason for this article results from my recent Cuba trip. I returned with over 6,000 images, many of which were three image brackets of -2, 0, and +2 stops. Partly to avoid buying more hard drives, and partly because I felt that I was in the mood for more realistic images, I combined the brackets into HDR DNG images in Lightroom, and then deleted the brackets to save hard drive space. After a few weeks I came to regret that decision, when I decided some images would have been more my style if I had the three brackets to send to Photomatix. So I began to experiment by sending some of the Lightroom HDR’s over to Photomatix. Photomatix will tone map a single image, but usually the results are not as good as sending bracketed exposures. I was surprised to find that the LR HDR’s processed as well as the brackets. It makes sense when you realize that the LR HDR may look normal, but it contains the greater range of highlights and shadows that were contained in the three brackets.
I found one sunset image where I kept the three brackets. This allowed me to do some comparisons in HDR processing. While it looks contrasty, this image did not have the sun showing and it was within the range of my sensor. Results would probably be different with a wider contrast range, at least when trying to process a single image in Photomatix.
Here are the three original brackets: -2, normal, and +2 stops.
Below is the normal exposure edited just using the basic tonal controls in Lightroom. It’s an acceptable image, but not very exciting. The drama in the sky that I remembered just isn’t there.
Below is the LR HDR image with no editing, with basic editing in Lightroom, and after mild high pass sharpening and NIK Color Efex 4 Tonal contrast in Photoshop. Now the drama in the sky is starting to pop.
This is the result of sending just the normally exposed image to Photomatix. This worked fairly well, because the scene contrast didn’t exceed the range of the sensor. The image on the left is just as it came from Photomatix. The second image is after high pass sharpening and NIK Tonal Contrat were added in Photoshop. It’s not too bad, but the clouds are pretty noisy.
Here is the result of sending the three brackets to Photomatix. High pass sharpening and Tonal Contrast have been applied. I fully expected this to be the clear winner.
And here is the result of sending the unedited LR HDR to Photomatix. Again high pass sharpening and Tonal Contrast have been applied. I was somewhat surprised to see that it’s virtually identical to the image created from the three individual brackets. It is obviously much better than sending just the single normal exposure to Photomatix. Even though I only sent one image to Photomatix, it contained all of the information available in the three brackets.
So, to answer my question “Do you need multiple Brackets?”
If your scene exceeds the range of your sensor, yes.
If your scene exceeds the range of the sensor , but you have created a LR HDR DNG image from multiple brackets, then no.
If your scene doesn’t exceed the range of the sensor, then maybe not. You can send a single image to Photomatix, but the results are somewhat less than optimal.
If your scene doesn’t exceed the range of the sensor , but you have created a LR HDR DNG image from multiple brackets, then no.
And to answer the question that started all of my experimentation: “Do I need to keep all 3, (or 5 or 7) Brackets?” The answer is now “Not really”, if you combine them into a LR HDR DNG before deleting them, and as long as there is no “ghosting” caused my movement from one image to the next. Photomatix needs the multiple images to fix that.
