Helpful Hero 3 Practice Above + Below the Waterline

GoPro's HD Hero 3 action cams are very popular for sure. Especially GoPro's top of the line HD Hero 3 Black Edition delivers stunning pictures above and below the waterline. And this despite its small size.

But right out of the box, video footage shot with the HD Hero 3 below the water surface still sometimes really sucks heavily, so how do we properly configure a Hero 3 Black Edition and then post-process (color-grade) the resulting footage to avoid such mishaps?

Actually, this article is the first article from the upcoming small series of blog articles in which I want to share my experience in getting the most out of a HD Hero 3.

GoPro HD Hero 3 Black (& Silver)

My focus is primarily on the GoPro HD Hero 3 Black Edition. With some limitations my article can also be applied to the HD Hero 3 Silver Edition. I don't cover the previous HD Hero and HD Hero 2 models as you cannot switch off the automatic white balance ... something that you need to do as the automatic white balance is prone to severe color distortions. This is especially true for filming in cold water.

The HD Hero 3 Black Edition also differs from the Silver Edition in that it comes with a much better video sensor. Despite the larger resolution, the sensor of the Black Edition produces much less color noise than the Silver Edition in the same situation. As we unfortunately are forced to switch off the cam-integrated color denoiser this becomes an issue in postprocessing video footage. I never managed to denoise HD Hero 2 Protune material, so that's why I'm suggesting to use only the Black Edition.

Update: GoPro has finally managed to break the Protune compression curve with the HD Hero 3+ insofar as raw Protune footage now comes with a significant sepia tint when WB is set to raw. Currently, it is difficult to fix such borked footage outside of Cineform/GoPro Studio. This is a really dumb idea on GoPro's side as this also breaks the usual work flow where grading happens after scene freeze. And GoPro Studio is a toy not suitable for real editing. Personally, I'm staying with my 3's for the time until GoPro cleans up this mess they've made.

Universal: 2.7K Wide

When it comes to the many different video modes the GoPro HD Hero 3 Black Edition offers you really should read Abe Kislevitz' blog article Understanding Your New GoPro.

If you don't care about memory storage, then I highly recommend to shoot in the 2.7K dimension, that are 2700×1520 pixels. This mode is where the Black Edition really shines. It only comes at 25 or 30 frames per second, but this should be sufficient for many dive scenarios.

Over the past ten or so months, I've found this 2.7K mode to be quite useful also for shooting aerial footage, unless you want to shot acrobatic flight. In such situations, you are probably much better of using the trusty 1080p mode with 50 or 60 frames per second. The advantage of the 2.7K dimension is that it gives you a lot of pixels for defishing in post production, so you don't loose too muh quality.

Note: traditionally, HD video image (frame) dimensions are specified in terms of their vertical size, such as 720p and 1080p. The final «p» signals that we get a full picture containing all pixel rows. In contrast, «i» means that we are getting only half the rows and the rows of two frames need to be interlaced in order to get the full picture. Interlacing is ridden by interlacing artefacts, such as the two half images not properly forming a uniform picture, especially when there are quick movements in a scene. Luckily, GoPro never went down this slippery slope and avoided this hack from the early times of video technology.

Probably thanks to marketing bubbling we got the term 2.7K instead of 1520p, the latter properly reflecting the vertical dimension. Consequently, it probably won't take too long to arrive at 4K in order to better see all the action sports inflicted wounds and blood in vivid detail.

But back to the here and now. Filming in 2.7K/1520 means that there is only exactly one POV/lens angle: wide. For the 3+, there is now an additional POV. Having only one POV may seem like a disadvantage at first. However, it really isn't one. If we look at the technical specs we can see why.

The HD Hero 3 has, as all other HD Heros so far, fixed focal length optics. The different POVs are emulated: the camera uses differently sized areas of the whole sensor area in order to achieve these different POVs. The sensor has 3840 pixel in its horizontal dimension. With 2700 pixels (or 2716 pixels to be precise) there is almost no reserve left for further more narrow POVs without having to scale up! And scaling up is bad as it creates pixel data that isn't in the original sensor data ... so it eats up space without any optical benefits.

The 2.7K mode is useful for this very reason: you don't need to care about the POV when filming. Later, when you are going to postprocess your footage, you can choose the frame you need for final 1080p output. This leaves enough room for either zooming up to 1:1 on the pixel level or scaling down. No quality loss.
  • The simplest way is to scale down the video clip from 1520p down to 1080p. This keeps the typical fisheye impression.
  • Alternatively, choose a suitable frame of 1080 pixels height.
  • If you place such a 1080 pixel cutout in the center you'll get a very moderate fisheye effect only. Depending on the particular scene, the fisheye effect may even hardly be noticable.
  • You can vary the fisheye effect by choosing a larger cutout.
  • Scale down from a suitable cutout to 1080p in order to get a lossless digital zoom.
  • Finally, the larger frame size allows you to decide how to frame only during video cut instead of having already to decide while filming. This way, you get some freedom to reframe during post processing.

What about True Colors?

There are a lot of add-on color filters being offered to GoPro HD Hero users, especially for filming under water. For tropical waters, red filters are all the craze. However, such red filters usually don't serve any useful purpose in our cold and filthy waters. If you really want to use filters nevertheless, go for the cyan ones in cold waters.

The main purpose of these filters is to help the automatic white balance in a camera do its job. In extreme lighting conditions they may also help with automatic exposure. Especially unexperienced users will benefit from filters. However, filters can also make problematic lighting conditions worse, especially in low light. Also, they may cause even more havoc to white balancing ... albeit they are supposed to especially avoid doing so.

In this article series I'm aiming at those who want to get more and better moving pictures from their GoPro HD Hero 3 Black Edition. I yet want to see users of red filters getting any noticeable benefit from these light swallowing devices. Instead, I've seen many clips with heavy discoloring. I've never had any good experience with my red filters on my HD Hero and HD Hero 2, despite them being very decent quality.

In fact, it is much more important to switch off automatic white balancing of the HD Hero 3. This way, without any automatic white balancing it cannot mess up your valuable footage, after all. Having used my HD Hero and HD Hero 2 was a great lesson in this respect.

So, in order to get suitable video footage from which you can work further to get decent final video, you need to configure your GoPro HD Hero 3 Black Edition this way:
  • switch Protune on, and
  • switch white balancing off.
Protune is GoPro's special handling of video data from the camera sensor before writing it to the memory card. I'll explain this in more detail in a few minutes, so let us tackle this new concept step by step.

When you switch on Protune, several things happen simultaneously that all have the consequence that you need to post process your video footage in any case. No pain, no gain. When you switch on Protune, your GoPro HD Hero 3 works slightly differently:
  • compression of sensor data is reduced, thus resulting in more video data per minute than before. At the same time, as writing bitrates go up considerably, you need better microSD cards that actually can handle the higher bitrates. Unfortunately, suitable microSD cards are a topic of its own.
  • no more automatic sharpening of the sensor image.
  • no more automatic saturation boosting.
  • the curve used for converting sensor red, green, and blue values into the values that are going to be written to disk is not linear but bent like the letter S. In consequence, there are more and finer steps towards the end of the curve, where the darkest and brightest values are. The curve is steeper in its middle part, this is where we don't need all this detail. (Note well: in fact, the curve is never linear but logarithmic, but that's a completely different story.)
In following blog articles I will show you how to post process such video clips which have been shot in Protune mode. It will then become clear what the Protune curve really is.

Did you notice? Our list lacks white balancing! The reason is that switching Protune on doesn't automatically switches off white balancing. Au contraire. However, only in Protune mode we're allowed to control automatic white balancing and to even switch it off completely. While you can set white balancing to some fixed given color temperatures, all of them are of no use for filming under water.

So, our only hope here is: switching in-camera white balancing off! Probably for reasons of marketing political correctness GoPro calls this «raw white balance». But in the end it really comes down to «WB off». This is exactly what we need!

Note: Automatic exposure control cannot be switched off with all the GoPro HD Heros so far and is always on, even in Protune modes.

Enable Protune and Disable WB

To properly set up our GoPro HD Hero 3 we first need to enter the camera settings. For this, press the mode button on the front of the Hero 3 multiple times until you see the monkey wrench symbol appearing in the LCD. Luckily, this doesn't mean maintenance required but settings instead. Now press the shutter button once to enter the settings menu.

While we're at it, you may want to try filming in 2.7K with 25 frames per second. Press the shutter button again. You'll then see a submenu listing the current video size, frame rate and POV. Using the shutter and mode buttons you can change the video size to 2.7K; the frame rate and POV are then fixed (unless you happen to have a 3+ which now features two POVs for 2.7K).

Please use the mode button to step through the many settings until you reach the capture settings. Press the shutter button to enter.

Again, use the mode front button multiple times until you see Protune in the LCD. It will most probably read OFF. So, press the shutter button, then modus to switch to ON, and then the shutter again. Now we're set, half of the configuration is done.

Now we need to switch white balancing off. Press the mode button again and you should see a new setting called WB. This setting is only available after you have Protune switched on. When Protune is disabled, you always end up with automatic white balancing ... and the problems it causes to your footage under water.

Press the shutter to change it and then use the mode button again to switch to WB RAW. Press the shutter button to accept this new setting. 

Please note that by pressing the shutter button for a longer time you will leave the settings menus completely and return to the top level, which usually is filming.

Arg, shocked? Shooting in Protune...

Raw Protune footage.
With Protune on, now shoot a short video clip, then look at it either using the LCD bacpac or any video viewer. You may probably be shocked: you are seeing a dull, flat picture without any contrast and flat colors. Booooring.

You will probably similar see something similar to what I'm showing to the right for illustration purposes. (Please note that I'm using a compressed image in this blog, so you see additional compression artefacts; these are not due to Protune!)

Be patient, this ain't the end. We will later learn (in a separate blog article) how to post process Protune footage in order to turn them into bright and vivid video.

After post-processing/grading the footage.
(grading, saturation and sharpening)
Just to give you a preview on what to expect, take a look at the next    image to the right. Putting personal color preferences aside, you should notice how bright and vivid the video material now appears. The advantage here is that you have almost full control over coloring, contrast, light, and sharpness to your needs and taste.

As usual: be reasonable in post processing, unless you want to mock a typical amateurish vacancy video look.

As usual, there is a simple rule of thumb: be reasonable in post processing, unless you want to mock a typical amateurish vacancy video look. I always find it interesting and also entertaining to see how much consumer cameras are sharpening and pushing color saturation.

However, there is something missing in my example shot: tint. But don't be afraid, I will show you some really tinted real-world examples in the following articles. I also still have so much GoPro HD Hero and HD Hero 2 footage where the white balance has gone berserk.

See you!

Update: Follow-up articles are Effectively Working with 2.7K Footage in Kdenlive, Post-processing Hero 3 Video (Above Waterline) Footage and Post-processing Hero 3 Video (Below Waterline) Footage.
Final note: I won't ever cover GoPro Studio. On purpose, this is a beginners' tool for those who are in need of quick results. If you, like me, rather want to understand what really happens and how post processing works, GoPro Studio is the wrong tool. Moreover, GoPro Studio doesn't fit into the overall workflow: you need to grade the raw footage before scene freeze; this is totally flawed. Finally, GoPro Studio, which once was Cineform Studio, only runs on OS X and Windows. I'm solely using Linux.