HDR Video Steps
Here’s some steps I’ve used for generating some motion/video out of HDR stills. There are many different workflows and I’ll touch on some of them from an overview perspective now. The first one is the workflow I employed for an older clip shot at Eden Gardens State Park in North West Florida. For reference, this is the clip (overview to follow below it).
HDR Video – Eden Gardens 2008 from Michael James on Vimeo.
I shot it with a Nikon D3 with a Nikon 14-24mm f/2.8G lens. It sat on top of a fluid head tripod I use for video work. I also had a shutter release cable attached to the D3. I set the camera to automatic bracketing and once I determined the mid point I switched from aperture priority to full manual so that each of the AEB sequences I was about to fire would be EXACTLY the same. I determined I would not need to go a full 9aeb and set the D3 to fire off 7 shots with 1EV steps between. I lowered the settings of the camera to shoot JPEG in a size that is larger than HD.
Also of critical importance is locking down white balance. I chose Daylight here (an obvious choice), but will often dial in an exact Kelvin setting for other lighting situations (although Kelvin WB selection is generally not available in lower end DSLRs).
If I wanted to shoot RAW I would not have been able to have captured the entire tilt move in just over 60 seconds due to the buffer issues, but the lower JPEG setting meant I would never tap out the buffer and could shoot burst after burst easily. Also, because the steps were only 1EV jumps between each of the 7aeb captures, I was comfortable only shooting JPEG. I would NOT attempt shooting JPEG for anything larger than 1EV jumps between each shot for this type of approach. Time was critical here to capture the entire tilt move in a short period of time. (I shoot RAW for all my other typical HDR workflows, including HDR Timelapse)
The shutter release of the camera was set to continuous so that I could hold down the shutter release cable button with one hand to fire off a full 7 shots at 9fps while keeping my other hand on the tripod handle to make small incremental movements to tilt up after each 7aeb capture. I do it this way to be quick enough to capture the entire tilt move seen in the video in a little over 60 seconds.
To repeat myself slightly now…, I have the camera ready to capture the brackets in continuous shutter release mode and then prepared for the first AEB capture by aiming the camera slightly below the horizon into the deep shadows. I then fired off a burst by holding down the shutter release cable button and quickly moved the tripod a very small (unmeasured and done by eye) amount; slightly tilted up for the next capture. Then again held the shutter release cable button to fire off another 7aeb and repeated this process until the tilt to the sky was complete. This took all of about one minute to capture.
Back home I dump the images to a folder on the computer and then I launched photoshop to begin the merge to HDR process. You don’t have to use photoshop as the program to merge to HDR, but back in 2008 when I put this together that was the process I used. I had a few scripts that I had created that had photoshop merge to HDR and then use custom settings to tonemap out to 16 bit TIFFs.
I employ two alternative workflows these days. One of which is where I merge to HDR in applications that batch merge and have them save .EXR files for each merge. Those .EXR files are then imported into either Adobe After Effects or Eyeon Fusion and then I use open source plugins to do the tonemapping in those compositing programs as well as the ensuing optical flow.
But in 2008 those plugins did not exist yet and this process I’m still describing was the workflow I used for the Eden Gardens sequence.
What you see below in the screen shot (click to enlarge or right click and open in a new window) is one of those 7aeb sequences in the merge to HDR dialogue. I’m just showing you that to show you that the dynamic range of the scene was pretty large for an outdoor shot and the sky was blown out when you could see the leaves straight ahead and the leaves were pitch black when the sky was properly exposed.
Like I said, there are several programs out there that can automate the process of merging and tonemapping your brackets and I plan to cover how to use them in this capacity in some future posts and training, but the process I employed here was a home grown merge to HDR and tonemapping recipe I used for Photoshop CS3. In the end I had 30+ Tiffs from that automated process to then use as the skeleton for an image sequence. I then take those Tiffs to the next step for optical flow treatment.
Before I move to that next step, here is a larger view (click for larger image) of a single tonemapped frame, along with the 7 shots above the top of it showing you the dynamic range covered for that one image.
The next step I did then was to take the TIFFs into Apple Shake which treats the group of single images like a sequence. I then used custom settings (see image below; click to enlarge) to expand the number of frames to be created BETWEEN each of the frames I was importing into it. In other words, Apple Shake was now going to create the frames and guess at the pixel movement between the frames I shot in the garden. There are other programs such as After Effects, Final Cut Pro, Fusion, etc that can accomplish the same thing with optical flow, but I used Shake in this instance.
I also recropped the image in Shake to match the ratio of HD footage and had it export the sequence as 1080p ProRes footage which I planned to send to Final Cut Pro to add audio and titles (see image below; click to enlarge).
Then I imported the 1080p footage into Final Cut Pro (see image below; click to enlarge) and added sound and some titles to export to various formats (including a web version which exists on Vimeo).
Posted by Michael James on Jul 6 2010 in HDR, HDR Timelapse, HDR Tutorial, HDR VIdeo Tags: HDR, HDR Capture, HDR Timelapse, HDR Tutorial, HDR VIdeo, tonemapping, Video
