Employ custom picture styles to get round your
DSLR’s dynamic range limitations
Whenever you record
video, pretty much whichever camera
you use, some of the picture information
is discarded during the recording process. How much you get to keep generally comes down to how much you spent on your camera in the first place – the cheaper the camera, the less data that will actually make it to your editing program.
A lot of this data loss occurs due to
compression. Raw video takes up a
huge amount of space. A 1080p video without any compression needs around
9GB per minute – that’s over half a
terabyte an hour. Video compressed using H.264, by comparison, typically comes in at a much more space-friendly 300MB per minute – only 18GB per hour, or the
same space as just two minutes of raw video.
Compression makes digital video much more
manageable, both from a capture and
management perspective. However, the
price you pay for this convenience is you have less data to start with, which gives you less flexibility when it comes to the
final look of your creation. One of the biggest casualties
is dynamic range – the difference between the brightest brights and the darkest darks in the image. With a
narrow dynamic range, you’re limited
in what you can change during post
production, as the image information simply isn’t there. This shows up in areas such
as shadows. With a wide dynamic range you can alter the setting to bring
out details that are hidden in the
dark areas of the image. If you only have a narrow dynamic range to start with,
that detail is lost: it will simply be black no matter how much tweaking you do.
As a rule of thumb, the more you spend on your
camera, the higher the dynamic range
it will record. However, there’s a feature you can use on some cameras that lets you increase the dynamic range on relatively inexpensive cameras so you’ve got more data to play with when it comes defining the look of your video later.
Quick brown fox – The free LUT Buddy plug-in from Red Giant Software lets you easily apply a LUT to flattened footage shot with CineStyle
The big killer of dynamic range is bits, or
rather lack of them. Dynamic range is
measured in f-stops, similar to camera apertures. The scale is logarithmic, so each successive stop halves
or doubles the amount of light. A very high-end digital cinema camera typically has a dynamic range of around 13 stops.
The sensor on the Canon 5D MkII, by comparison, has a dynamic range close to 12 stops,
which isn’t bad for a camera costing
a tenth of the price of a high-end cinema model. But the big problem with the
5D MkII is that while the sensor can see
that dynamic range, a lot has been discarded by the time it gets to the file
stage, primarily because it records in an 8-bit format, which isn’t capable of recording that level of detail.
You can get around this, though, by way of
picture styles. Like many other
DSLRs, the 5D MkII uses picture styles to change the look of an image in camera. The important part is that sensor data is processed before it’s reduced
to 8-bit, so you can try and save some
of that data before it’s discarded.
In addition to the built-in picture styles,
you can create your own and upload
them to your camera. The aim, if you want
to preserve as much dynamic range as
possible, is to shoot with a picture
style termed flat. This maximises the information in the image,
although it will appear washed out when
it comes out of the camera. It’s not a look you’d want to use straight from the camera,
but it can provide greater flexibility when it comes to colour grading later on. If you don’t plan to tweak your video using colour grading to achieve a specific look, you should use one of the preset picture styles. However, if you’ve found the presets limiting when it comes to
grading, it’s worth experimenting with custom styles.
Creating your own from scratch is possible, but there are many available online, most notably Tehnicolor, which offers a picture style called CineStyle for free on its website. The first step to getting a custom picture style
onto your camera – CineStyle will work on any Canon DSLR – is to use the bundled Canon utility. Just hook up
your camera, load in the picture style and select which of the three custom presets you want to put it in. Once it’s loaded,
Technicolor recommends that you set the picture style settings to Sharpness: 0, Contrast: -4, Saturation: -2 and
Color Tone: 0. Now, when you record video, the CineStyle picture style will be applied to the camera data before it’s saved to a
file. The result is an image that has
much more detail in darks and lights, making it much better suited to colour grading during postprodu ction work.
Using CineStyle isn’t without its problems.
First, the image you see when
recording is washed out, making it tricky to properly set exposure. One way around this is to use one of the preset styles when setting exposure and then
switching back to CineStyle when it
comes to actually recording.
The next issue is how to get the footage looking
less washed out when editing.
Luckily, Technicolor provides what’s called a look-up table (LUT) that will bring back the
darks and lights that were flattened
during recording. The free LUT Buddy plug-in from Red Giant Software
(redgiantsoftware. com) provides a
simple way to apply the LUT to your footage. Just drop it on your clip,
load up the supplied LUT and the shadows
and highlights will be restored. This is really just a quick fix, however. If you only intend to apply the LUT in post, you’re probably better just recording with one of
the preset styles and your video will be quicker to process.
Where CineStyle comes into its own, though, is
when you want to grade your footage
to create a specific look for your video.
The flat style provides a great starting point and lets you play more with the colours. It’s not perfect and because you’re trading which data you’re storing within
the same 8-bits, it will still break
down if you push it too far, but if you know what it can do, you can
get great results. The key thing is
to experiment on footage that’s not being used for a live project. Only by trying out
how the footage holds up to post production
will you know what it can and can’t do.
CineStyle and other
picture styles aren’t a magic bullet, but they’re good to have in your arsenal. Even better, all the tools required are free, so you can download them
and play around with them without it
costing you a penny.
Picture styles aren’t unique to Canon’s
cameras. It’s the only DSLR platform
Technicolor has embraced, but you can get a similar flat style for
Nikon DSLRs: Google ‘TassinFlat’ and you’ll
find a similar picture style that will give a you flat image from your Nikon camera suitable for later colour
correction.
(1) The standard
picture style looks decent out of the camera but loses detail in the lights and darks
(2) The raw footage
shot with CineStyle retains more detail,
but looks washed out
(3) Applying the LUT
makes the CineStyle footage less
washed out, but still retains a bit more detail than the sttandard picture style
(4) Colour correction
is where a flat picture style really
comes into its own – the standard style quickly loses detail
(5) The CineStyle
footage can be pushed further in colour
correction and retains more detail
(6) If you’re applying
a specific look to your film, you’ll
lose detail with the standard picture style
(7) CineStyle gives
you much more detail even with an
extreme look applied
(1) Again,
the standard picture style loses detail in dark areas of the image
(2) CineStyle
retains more detail for the
same exposure setting
(3) With
just the LUT applied, more detail is visible in the CineStyle footage
Compared with the standard picture style, with both standard (4) and CineStyle (5) colour corrected, you can see details outside the windows
and also on the dark table in the foreground
When you apply an extreme look to both, the CineStyle footage
(6) gives much more of the original detail than standard footage (7)
