Pixiq

"Perhaps one day, there will be an in camera HDR solution that will produce the kinds of HDR that can be done with multiple RAW exposures. Until that time, we will need to live with the more laborious means we now employ and perhaps a few compromises for shooting motion subjects."

This post has been updated to clarify the use of ISO Bracketing to create a single image HDR. To my knowledge, the method works as well as any other single shot process.

Since writing the original post, I have tested the theory and found that there is actually no real difference between processing a single RAW file and using this technique. All of the single image methods, I have posted, including this one, are capable of producing equivalent imagery. The question, is whether there is any advantage using one method over any other.

When I discovered that the Olympus interface has an option for ISO Bracketing, I started to believe that the Olympus might have a unique feature within its interface that made a single exposure HDR easier to produce. I now believe that this is not exactly the case.

ISO Bracketing is different from AEB Bracketing. 

ISO bracketing in normal use, simply changes the sensitivity reading for a given exposure. This functions to simulate three exposed images taken at different ISO values by interpolation. In normal use, it allows for different exposures without the need to change the shutter speed or the aperture. This function, produces three different ISO exposures from a single RAW shot.

While there is no more real data in these three images than are found in the single RAW, the fact that it produces the EV value meta tags automatically can be a timesaver when bringing the files into Photomatix Pro. However, it will produce three RAW files on your memory card. For some, this may not be worth the memory space.

When looking at the files on camera, or later on the computer, there seems to be a significant difference in the three exposures.

If there is, Photomatix Pro is not processing that difference. In my testing of this theory, I have found that the outcome, although very convincing as HDR, is not any different than any other single shot method. When using Photomatix Pro default settings, all of the single shot methods produced the same results, no matter what ISO setting was attached.

This simply shows that a single RAW file can produce a very nice HDR look. The method doesn't seem to make any difference to the final outcome.

The manual indicates that three images are taken. It seems to me that only one is taken but it is interpolated to produce three images on the memory card. The proof of which would show in motion subjects, as any lag would be recorded in the image as ghosting. This seems not to happen in any of the images I have produced.

I occasionally find discrepancies when reading through camera manuals. This happens when it is too difficult to explain something as obtuse as image interpolation to a novice. Sometimes you have to read between that lines in order to realize what is going on.

"ISO BKT (ISO Bracketing) – In AE BKT the camera performs the bracket by changing the shutter speed and f-stop combinations for the series of exposures. There may be situations in which it is desirable to maintain the same shutter speed and f-stop through the series of bracketed images. The first image uses the exposure determined by the camera at the preset ISO, the second image uses a lower ISO and the final image uses a higher ISO. The degree of underexposure and overexposure are set in the camera’s menu." - Source Olympus

While the above seems to imply that three different shots need to be taken, the actual function only requires a single shot which is interpolated. Three images with different ISO are automatically created from one captured image.

While the technique produces a reasonable HDR, it seems that there is no major advantage over any other single image method.

ISO bracketed images seem not to have any real advantage over simply tone mapping a single image.  

Olympus is the only camera that I know of, that has ISO Bracketing capability (as described above) built into the camera software.

In my testing, ISO Bracketing produces what seems to be the exact same results as a single RAW image in Photomatix Pro. All of the images in the gallery, could in theory be produced from any of the Single methods I have been discussing in my previous posts.

Perhaps one day, there will be an in camera HDR solution that will produce the kinds of HDR that can be done with multiple RAW exposures. Until that time, we will need to live with the more laborious means we now employ and perhaps a few compromises for shooting motion subjects.

For me, ISO Bracketing once seemed like a dream come true. Now, I am convinced that it has little to no advantage. It works, but it may not be advantageous over any of the other techniques mentioned.

For more reading about my HDR techniques and to see more HDR images, please follow these links.

Single Image HDR by Interpolation 

SS HDR - My Way - Part 1

SS HDR - My Way - Part 2

SS HDR - My Way - Part 3

SS HDR Gallery

NOTICE:    THIS POSTING AS WELL AS ALL PHOTOGRAPHS AND GALLERY IMAGES ARE COPYRIGHT - © JOHN NEEL AND ARE NOT TO BE USED FOR ANY PUPOSE WITHOUT WRITTEN CONSENT FROM THE WRITER, THE PHOTOGRAPHER AND/OR PIXIQ. THE IDEAS EXPRESSED ARE THE PROPERTY OF THE PHOTOGRAPHER AND/OR THE AUTHOR.

Please read more of my posts regarding Digital and Analog Photography on Pixiq. 

"Rethinking Digital Photography - Making & Using Traditional & Contemporary Photo Tools"