HDRI is an interesting effect that, if used in certain instances, can create some very artistic photographs.
The technique combines three photographs, taken of the same scene, at three different exposures. This combination allows the viewer to see a light range higher than what the average camera (and sometimes human eye) can photograph. It allows you to see detail in shadows and light areas that would normally be too dark or blown out.
Problems arising with creating an HDR video stem from the ability to take three different exposures. At the moment, I know no video camera that can take three (or more) different exposures of a single frame. A fix for this would be strapping three cameras together, which will cause some huge complications with focus, zoom and perspective. Not to mention the price of purchasing three HD cameras.
What this Faux HDR effect does is push the exposure in both directions from a regular video clip. While this is not true HDR, you can see a similar effect. Shadows will be lighter and light areas will have more detail. For those lucky few who own a camera that can capture RAW video, your footage will look the best because you can actually push the video up or down a couple of stops. For those of us who don't have $30,000+ on hand, we can still get a pretty nice effect.
What we need -
Adobe After Effects (I used CS5, but older versions may be able to work)
A Video Clip.
-I found that well exposed, and even slightly underexposed video works best. Overexposed video does not look good. I've also found that shade or cloudy days work much better than direct sunlight. Mostly because a camera loses a lot of detail in the shadows when you have an incredibly powerful and uneven light source.
Step 1: Import Your Video
The first thing we need to do is import our video and create a new composition.
If you are familiar with After Effects, this is a pretty basic step. If not, please look up how to use After Effects.
Step 2: Duplicate
Duplicate (Ctrl+D) your video in the timeline to create three separate instances.
Your top video will be the dark areas.
Your middle video will be the bright areas.
Your bottom video will be the mid areas.
Having the mid areas on the bottom allows the dark and bright details to show onto the video. Since the details are already there for the middle exposure, we use this to fill in (you'll see this in action, soon) the rest of the video.
Step 3: Change Exposures
Head into 'Effects and Presets' and search "Exposure". Under the 'Color Correction' tab you will see an effect called "Exposure".
Apply "Exposure" to the top and middle clips on your timeline.
Change the exposure on the top clip to "+1.5"
Change the exposure on the middle clip to "-1.5"
Note : You can push these exposures as high or as low as you want, to get your desired effect. I typically find that +/- 1.5 looks the best but feel free to experiment. I also find that you can push the top exposure a bit more than the bottom exposure. Always feel free to experiment with the numbers I give you to get your desired effect.
Step 4: Duplicate/Luma Matte
Duplicate the top clip (Ctrl+D). You should now have two identical clips with exposure +1.5.
Select the bottom of these two (exp +1.5) clips.
In the timeline, in the "TrkMat" section, use the pull down menu and select "Luma Inverted Matte".
This will effectively remove all of the sections of the image that are too white to hold detail.
Now, we are going to do a very similar thing to -1.5 exposure clip.
Duplicate the -1.5 clip (Ctrl+D). You should now have two identical clips with exposure -1.5.
Select the bottom of these two (exp -1.5) clips.
In the timeline, in the "TrkMat" section, use the pull down menu and select "Luma Matte". (Remember how we did "luma inverted matte" before? Just do "Luma Matte" now.)
This will effectively remove all of the sections of the image that are too dark to hold detail.
Step 5: Finishing Touches
At this point you are essentially done with your HDR Video, but there are a couple of finishing touches we can add to create a couple other effects.
Fine tuning the HDR
Search for the effect "Gaussian Blur".
Place this effect on both of the upper clips of your two exposures (the ones that done have the "Eye" selected).
These invisible clips are giving your visible clips the data they need to make the areas that don't have much detail transparent.
If you blur them, however, you will start to see more sharpness coming through from the mid exposure clip.
You'll notice that blurring the bottom (-1.5) clip hardly does anything to the image. This is because this clip is showing us detail in brighter areas. The reason to blur this is to make a smoother transition between the bright an middle exposed areas. You don't need to blur it too much. I usually use a blurriness setting of "2"
The top (+1.5) clip has a different effect when you blur it. This clip is in charge of bringing out details in the shadow. When you blur it's transparency layer, you are starting to allow shadows to show through this detail, making these areas darker and the image appear sharper. For a soft image, keep it at "0", for a sharp image, bring it up to "10".
Feel free to experiment with these blur numbers.
After you're done with the HDR
Another thing you may decide to do is manipulate the image a bit more after you are done creating the HDR effect.
Add an adjustment layer to the top.
Add the "sharpen" effect to make the image a bit sharper.
Add the "Curves" effect to adjust the bright and dark spots.
Also, the color of your image may end up a little red. You could do some color correction in this layer, too, if you wanted to adjust the color temperature.
Alright! You're done. Always remember, have fun and experiment with these effects to get a good HDR video. All images are different and while the principles may be the same, the effect may need to be adjusted depending on what the image looks like.
Thanks for checking out my tutorial