hpr-knowledge-base/hpr_transcripts/hpr2175.txt

Episode: 2175
Title: HPR2175: Kdenlive Part 4 Colour Correction
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2175/hpr2175.mp3
Transcribed: 2025-10-18 15:18:55

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This in HPR episode 2,175 entitled, K-Men Live Part 4 Color Correction, it is hosted
against and in about 18 minutes long, the summer is, a review on the K-Men Live Color Correction
Suite.
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Hello again HPR listeners, this is Gettys with you again with K-Men Live Video Series
Part 4 Color Correction.
The topics included are workflow, the human element, loom of values, levels, colors, things
that look broken, saturation, copying values between clips, color effects, selective color
correction and rotoscoping, and finally conclusion.
So let's get started.
K-Men Live Photography doesn't just happen, careful attention to lens settings, depth of
field charts and lighting will produce quality images, but even those since the days of
the early photography have been taken into the darkroom and adjusted.
K-Men Live's Color Correction Suite easily rivals any professional video edit in application,
and in many ways surpasses the basic tools often found in the expensive industry application.
Let's look at the typical workflow of color correction and then tools.
Workflow Color correction comes into play fairly late in the post-production process for two
reasons.
First, you don't want to spend hours color correcting footage, only to find that later
in the edit the footage is cut entirely from the movie.
Second, adding color effects to all your footage is burdensome on your computer and logistically
difficult for you to keep track of during intensive editing.
So you'll wait until picture lock to start color correction.
Frequently, it's done at roughly the same time as the sound mix is being done.
The workflow of post-production itself will be discussed in further detail in the final
article of this series, without exception color correct your work seen by scene.
Your eyes treat color very subjectively.
A shade of blue that looks too bright one moment starts to fall into place after the
eye has stared at it long enough.
So you want to immerse yourself in one scene and adjust the colors only within that scene,
so that your eye absorbs the colors and character of that scene as normal.
When the camera cuts to a different scene, both you as the colorist and the audience understand
that the color should be different.
We're in a different location now.
So of course, the colors of our hero's skin tone can be drastically different and will
understand why.
Within the same scene of course, that tends not to be the case.
For human element, the human eye naturally gravitates towards other humans, so unless
you're making a documentary about animals or plants, your audience mostly cares about
the humans in your movie, or at least their eyes mostly care about the humans.
For that reason, a good colorist first targets the human in the shot.
Luma values.
Start with the Luma.
Luma is the term used for the levels of your picture's brightness values.
If you were to desaturate your picture so that it was black and white only, then you'd
be looking essentially at the pure Luma values of your image.
The reason this is significant is because Cellulide has a white tolerance for Luma.
Open brackets, according to the responsive sensitivity of the film stop film close brackets.
Think of it as a resolution for the scale from darkest black to brightest white.
First of all, Cellulide can read darker shadows and brighter highlights.
And second of all, the graduation between these two extremes is constant and even.
So even in the darker shadows, there is still great detail.
Video represents a relatively small inset within the Cellulide sensitivity spectrum.
With its darkest value being early in the shadow levels of Cellulide, and its potential
white level being quite early in Cellulide highlights, anything below this dark level
or above the light level bottoms out quickly.
And actually causes distortion, open brackets, which is precisely why our video camera has
a zebra straps function on it close brackets.
Furthermore, the progress from dark to bright is not constant and features less variation
than Cellulide.
In other words, your audience is accustomed to seeing a medium with a colour range almost
as rich as real life and are instead being presented with a digital reproduction.
Since most video is shot to capture a reality, open brackets or suggest that it has captured
some form of reality close brackets, and to the audience reality on film is the look
of Cellulide.
Open brackets, yes, the film industry has trained audiences that film grain and perfect cinematography
equals reality close brackets.
The colourous goal is to fake a more filming look and feel for their video.
The most effective way to fake Cellulide like Luma in your video is to crush the
darks and pop the brights.
In other words, increase the contrast.
There are many ways to do this, but my favourite is the Curves tool.
To add a curve to a clip, right click the clip in the timeline, and select Add Effect,
Color Correction, Curves.
Activate the Effects tab, open brackets, see the previous article on how to modify your
layout and add tabs to your interface close brackets.
Bring the bright level up by clicking the top part of the curve and dragging it to the
left.
Bring the dark level down by clicking the bottom end of the curve and dragging it to the
right.
This makes the graduation between the two extremes less constant, so the result is that
the image now has more drastic dark levels and more drastic bright levels.
Note that this is actually lessening your video's Luma variants.
In other words, it's making it even less like Cellulide by further restricting the Luma
potential.
However, to the audience eyes, it now looks more like Cellulide, because the dark areas
of the image are richer and the bright areas appear brighter, like on film.
Levels
Another Luma modification tool is the Levels effect accessed by right-clicking the
clip, Add Effect, Color Corrections, Levels.
It's a less graphical interface, so might be less user-friendly, but it's a powerful
way to control the input and output levels of each value.
Its controls are available in the Effects tab, as long as the clip is highlighted.
As with the curves, the default channel is red, so if you want to target the Luma
values first, then use the drop-down menu in the top right of the Effects tab to choose
Luma.
Colors
Next, you can manipulate the chroma values of your image.
This is done in the exact same way as you would adjust for Cellulide.
Use your human subject as your guide.
In skin, regardless of tone, loves amber.
Increasing the red and yellow values in a shot with human flesh in it makes the subject
look warmer and more alive and vibrant.
You can use the same toolset as you did for Luma adjustment, but be sure to add a new
effect for each channel you adjust.
You cannot use the same effect for different channels.
You will simply be overwriting the Luma adjustment if you switch an existing curve over to
the red channel.
The order of effects matter, it's a stack.
So anything at the top of the stack is affecting all the effects below it.
This is why I start with the Luma values.
I find that if I adjust color first and then place a Luma curve on top of all these,
I find that the colors are in danger of becoming posterized and need to be dialed down.
So start with the Luma and then move on to the colors.
If you are using curves for the color adjustment, then knowledge of basic complementary colors
will help.
As I've stated in an article on a different video editing application, open brackets
written back in the dark ages before I'd switched to a free software solution close
brackets, there's a simple new modic that my cinematography teacher gave me to remember
the relation of colors in the digital world.
It comes in the form of some stock trade advice.
I quote by General Motors and RC Kohler translated that's by as in BUY equals BY blue and yellow.
General Motors equals GM green and magenta RC Kohler equals RC red and cyan ago or further
translated.
If you add red to a shot, you are necessarily reducing cyan.
If you add green, then you reduce magenta and someone and vice versa.
The curve's interface makes this abundantly clear, since one side of the curve will be
for instance red and the other cyan.
You can target certain areas of the image according to which part of the curve you manipulate.
You can add red primarily to the mid tones where human skin tone is by moving the middle
of the curve more into red.
And strain the darks and highlights to prevent their red levels from changing.
You can also use the levels tool for color manipulation.
Select the red channel to begin with and adjust the different levels of red.
I find this slightly less useful since it's not possible to target just the mid tones.
And yet sometimes it produces a rich result that would less.
So try it out.
But another tool you can use for color adjustment is the RGB adjustment effect.
This is a straightforward manipulation of the levels of the RGB values in the image.
Again, there is no target just a specific range, i.e. just the highlights or just the mid tones.
So I tend to reverse it for overall adjustments.
But combined with other filters, I've used it for primary skin tone adjustment depending
largely on the lighting situation and color depth of the video.
Things that look broken.
The tool that most video editors and colorists will default to when looking for quick color
correction will be the three point balance in effect because in some profession applications
that's the name of the go to tool for color correction.
The three point balancing tool in KDN Live is nothing more than a dumbed down curve front
end.
And it is first applied to image inexplicably turned cyan.
And the color select droppers are completely literal, such that if you select some area
of the image as your white point, it assigns cyan as your white point, turning your image
into a bad parody of a cartoon effect.
The correct way to use this tool is probably not to use it.
Use the more powerful curves tool instead.
But if you like this simplified interface, then manually select shades of grey using
the color picker, obtained by clicking on the color swatch by the black level, grey
level and white level.
You'll also notice that there is no color wheel interface in KDN Live.
To any traditional colorist, this will probably be a deal breaker.
Luckily, I'm not a traditional colorist, and neither should you be.
The tools of the trade are changing, and the color correction tools in KDN Live have
proven themselves to be powerful, flexible and effective.
They have easily matched the color tools in any other professional video editor, used
in the production facility I am part of, and in many ways they are more efficient.
The ability to manipulate colors on a curve, for instance, therefore having a built in
ability to immediately target the loom arrange that those colors are changing within is an
amazing time saver.
Saturation.
Finally, the saturation of the image can be adjusted.
You can create a more vibrant look with very saturated colors.
A dull and stark image with less saturated shades, go completely black and white with a
saturation level of zero.
The tool for this is fairly straightforward.
Add effect, color correction, SOP, saturation.
Add this tool a clip and use the controls in the effects stack to modify the slope offset
power of individual channels, or the levels of the overall saturation.
A level of zero saturation will render a black and white image.
Copy and values between clips.
Obviously, if you want to reapply and redo the color correction from one shot of your
subject to the next, I wouldn't be recommending you do any color correction in KDN Live, but
it's easy to copy color settings between clips.
The first method is to right click on the clip in the timeline, containing the color
effects, move to the clip in need of the same, open brackets or similar if you just want
to start from approximate the same place close brackets, color adjustments and right click
on it, choose paste effects, now tweak the color adjustments as needed.
You can also save your own effect settings, such that they will be available in your effect
menu.
In the effects stack, click on the save icon under the effect you wish to save.
Enter a new name for the effect.
From now on, you can apply that effect with those settings onto any clip by right clicking
on the clip, add effect, custom.
Color effects.
As a final note on stylizing your images look and fill, remember that you have different
compositing options available via the right click, add transition menu.
By layering one clip on top of itself and adding a multiply transition between them and
then adjusting the saturation or color values of the bottom clip, you can create a new
composited image with some very interesting effects, such as the classic Bleach Bypass
look.
If color correction and rotoscoping, if your subject is not moving or if they are moving
and you have a lot of time on your hands, you can rotoscope the subject to isolate it
from the rest of the image.
You're then able to effect only what is visible within your selection.
Rotoscoping and masking is something of an art and is often considered a relative to
animation, especially when your subject is moving around and you need to create a rotoscoping
that moves accordingly.
But the basics are simple, add a rotoscope to your video clip, select the area you wish
to keep and composite.
To try this, place a video on track 2, right click on it and select miscellaneous rotoscoping.
In the effects stack, set the mode to alpha so that anything not selected is converted
to an alpha channel and ensure that the alpha operation is set to white on clear.
In the project monitor, click around the object that you wish to effect on that layer.
After you close your selection, only that object will be visible in that video track.
Now add another track on track 3, just under that clip and right click on the top track
to add a composite transition, open brackets, see the previous article on transition and
effects from what information close brackets.
In the context of color correction, I add the same clip under it so that it appears that
there has been no rotoscoping at all.
It looks like one complete image, but now add a new effect onto the top track, such as
a curve and adjust its color.
It's successfully isolated adjustment on that object to only that object.
Obviously, the use of rotoscoping goes far beyond color correction, but since it's usually
touted as a killer feature of dedicated color correction applications, it's worth mentioning
here.
Conclusion
This article shows that KDN Live is not just a capable video editor, but also a color correction
suite that matches some of the high end color applications available.
Not only is it flexible, but it's efficient, don't let it's lack of some traditional
conventions for you, powerful color correction is easy with KDN Live.
And that's the end of KDN Live, part 4, color correction.
Your feedback and comments are welcome, and this has been Gedis, the Hacker Public Radio,
and we'll meet again in part 5.
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