Canon 7D: Optimizing DSLR video dynamic range

There’s a great tutorial over at Vimeo on controlling the dynamic range of digital SLRs when capturing video. It turns out that the video mode of digital SLRs is tuned like a typical JPEG mode: To get a contrasty, “finished” look right away. But like JPEGs, this means a lot of tonal and color information is tossed out before the capture is saved, which can be limiting if you need a look that’s different than what the camera gives you. If highlights are blown or shadows are plugged, you may be left with nothing to work with at the high or low end when you try to adjust the image quality.

The technique covered in the video linked below involves using Canon Picture Styles (presets for how the camera processes images) to dial down the contrast and color in an attempt to squeeze as many of the original scene’s tones as possible into the range the sensor can capture. A file captured this way looks flat and lacks contrast, and isn’t something you would show as finished. But that’s because, as with raw capture or like Ansel Adams shooting film, we are at a step in the process where we’re not trying to create a perfect picture at the moment of capture, we’re trying to capture enough of the right data from which we can produce a perfect picture in post-processing. That’s an important difference.

It’s also important to understand that this capture technique isn’t quite as good as actually capturing video in raw format, but video cameras that do are pretty rare and I think most of them are expensive and called RED. This technique is about doing the best you can with the non-raw capture you have.

This capture technique is often called increasing or maximizing the dynamic range, but I prefer to call it optimizing. You’re not making the sensor capture more tones, you’re rearranging the tones you’ve captured before they’re recorded. I suppose you could call it maximizing the available dynamic range.

Here’s the URL to the video:

While the video talks about the technique in terms of the Canon 7D, Canon Picture Styles can be used with the 5DMkII and others. And the principle can be applied to other brands of cameras that give you control over the image quality of the video.

(Update: [May 2011] You might want to try the new Cinestyle picture style by Technicolor and Canon, a more “official” version of the picture styles described in this post.)

Stuttering video playback on PowerBooks and iBooks

If you experience stuttering, jerky video playback on an Apple PowerBook or iBook, here are some ideas.

Check Energy Saver settings. Open your System Preferences and click Energy Saver. In Energy Saver, click the Options tab. Now check the setting for Processor Performance. If it’s set to Reduced, change it to Highest or Automatic. Video playback may be smooth now.

If you’re running on battery, be sure to change the Processor Performance setting back to Automatic or Reduced when you’re done watching video. The Highest setting drains the battery the fastest. Note that on a notebook, the Energy Saver preference lets you save different settings for Battery and Power Adapter.

You might see the effect of the Reduced setting any time you perform processor-intensive tasks such as audio or video rendering, or gameplay. In those situations, you’ll want to set Processor Performance to Automatic or Highest.

Note: The Energy Saver tip won’t work with MacBooks and MacBook Pros, because Intel CPUs automatically try to balance smooth playback against battery drain. The older PowerPC CPUs were not as smart.

Check for other processor hogs. If you set Processor Performance to Highest and you still see choppy performance, the cause may be another application that’s using processor cycles. Open your Activity Monitor utility, view the CPU tab, show all processes, and sort the list by %CPU to see if any applications are using an unusually high percentage of CPU cycles. While new computers can handle today’s streaming video easily, the same video demands almost all the CPU power available in older computers, so any unnecessary tasks can interrupt smooth video playback.

Watch out for HD video. If you have a PowerBook or iBook, you’ll probably have to avoid HD and choose the SD (standard definition) option when you watch Internet video. Smooth HD streaming works best with a recent Intel multi-core CPU. When PowerBooks and iBooks were made, Internet video was much lower quality and there was no high-definition streaming. As CPUs got faster, what made high-quality HD streaming possible were new codecs that made up for limited Internet bandwidth by leaning on the CPU in your computer to process the highly compressed stream. Newer Intel CPUs are optimized for those codecs, so they can decompress video files and Web streaming video very quickly without slowing down the whole computer.

But the G3 and G4 CPUs in PowerBooks and iBooks do not have those Intel optimizations (PowerPC G3 and G4 CPUs were not made by Intel), so they are are too old and slow to decode HD without stuttering. A PowerBook G4 might have a CPU running at 1GHz, while a MacBook Pro has multiple multimedia-optimized CPU cores running at over 2GHz each. Even an old, used MacBook Pro has many times the processing power of a PowerBook G3 or G4.

Also, check the speed of your connection to the Internet. You need a fast enough connection to stream HD smoothly. My old Internet connection was too slow for HD streaming, forcing me to watch SD streaming even on my newest Mac, or let HD video buffer longer before I play it back. My current Internet connection is capable of carrying HD video data fast enough for smooth playback on a computer that’s fast enough to decode it.