Bill Davis
Forum Replies Created
-
Oddly, I just spent a small chunk of time this AM chatting with Phil Pan on-line regarding this general topic.
(Hint: there are plenty of solid reasons to eschew Facebook participation, but as a modern means of connecting with expertise if used judiciously, it has few equals, IMO.Just prior to our chat, he had posted a general overview of color science terminology that I found HUGELY useful as I start to learn more about this topic.
With his permission, I’ll post it below.
But the one thing it has utterly convinced me of is that color science is complex, it’s implementations in modern software are evolving, and I’m WAY dumber about these things than I ever imagined.
This was his response to some questions about basic color science as it relates to the new stuff in X…
Phil Pan:
Let’s start by defining the vocabulary.
The term ‘Brightness’ is defined by the Commission Internationale de l’Éclairage as “the attribute of a visual sensation according to which an area appears to exhibit more or less light”. Brightness is therefore, by the CIE’s definition, a subjective quantity that cannot be measured. Brightness doesn’t have a formula or units, contrary to CIE Luminance and CIE Lightness, which do. Brightness should be understood as the subjective effect (the adjective of its appearance) of Luminance.
The CIE defines Luminance as the radiance weighted by the human spectral sensitivity function; Luminance, measured in candelas-per-square-meter, is the human vision (perceptual) equivalent of Radiance (measured in Watts per steradian per square meter). In film/video reproduction, only Relative Luminance is used (Luminance relative to a defined white level) — this quantity is denoted “Y” and has linear characteristics in relation to physical radiance.
Because of the characteristics of the human visual system, a linear/uniform increase in Y intensity yields a non-uniform increase in brightness perception. To compensate for this, the CIE has defined a uniform brightness scale, called Lightness (denoted L*, pronounced ‘L-star’), which ranges from 0 to 1, and which has a characteristic power-function curve. Each increment of 1% in Lightness is not only perceived as a uniform increment, but constitutes also the threshold (the ‘just noticeable difference, or JND) of brightness perception (denoted “delta E”).
In video systems, for matters of computational efficiency, an approximation of CIE Lightness is used, which is called Luma; it is Luminance raised to a gamma factor (say, 2.2) and is denoted Y’ (‘y-prime’). Exposure and Contrast are different beasts altogether.
Exposure is a dimensionless quantity that is related to the Irradiance of a photonic device (Watts per square meter), or how many photons hit its surface per unit of time. Exposure Value (EV), which is colloquially called ‘f-stop’ is set in an exponential scale (doubling or halving photon count). “Changing the exposure” in a numeric simulation that is properly engineered in linear (relative Luminance) units, is the same thing as applying an additive (‘offset’) to the input values.
Contrast is a subjective value (similar in semantic function to Brightness) that is related to the ratio of two Luminance or Reflectance stimuli. When applied to an entire image, contrast refers in essence to both the spread of its histogram and the barycentre of this spread (the contrast ‘pivot’).
Gain is not a unit of colour science, but a term in electrical engineering which is a simple multiplier. A gain of “2” is a multiplication by 2. A gain of “0.5” is a multiplication by 0.5.
Setup (also called ‘pedestal’ or ‘black level’) is an archaic term from the days of composite NTSC. It represents the (paradoxically ‘visible’) black level above horizontal blanking (the level at which the electron gun’s spot had to invisibly cross the frame to draw new scan lines). Since there were no less than three NTSC standards for black level, old analogue systems had a “setup” parameter so one could conform their black level to whatever NTSC standard they were using. The most common Setup (black level) was pegged at 7.5% of picture excursion. The term ‘picture excursion’ comes from the defunct american Institute of Radio Engineers (IRE), which defined electron gun blanking at 0 IRE units and white level at 100 IRE.
Avid is the oldest digital video software company on the block and its tools are laden with legacy items that will not be removed until the last user from the old analogue broadcast days retires. It makes zero sense in 2018 to use analogue-days nomenclature and units; nor does it for Final Cut to still show a waveform monitor that expresses picture excursion in IRE units, with antiquated concepts such as ‘superblack’ and ‘superwhite’. But the FCP team didn’t have much of a choice, since it needed to compete with Avid in what had become a buttoned-up, conservative market.
In 2008, the American Society of Cinematographers’ (ASC) Technology Committee, defined a bare bones (minimum common denominator) colour decision exchange standard, to enable dissimilar digital imaging systems to achieve and conform the most basic colour grading styles among each other. The Color Decision List (CDL) format is an XML structure that defines four control dimensions: Slope, Offset, Power and Saturation.
Translated in video systems, Slope is the resultant linear angle of the video transfer function achieved through a combination of Lift and Gain. Slope affects contrast (the steeper the slope, the more contrast). Offset is the same thing as either ‘Brightness’, ’Setup’, ‘Offset’, ‘Exposure’ or ‘Picture Level’. Power is the same thing as ‘Gamma’. And Saturation is the same thing as HSL saturation (amount of chroma).
Kodak’s Glenn Kennel and ILM’s Josh Pines chose these units because they encompass a pretty wide array of possibilities and can easily be converted to and from legacy colour grading systems in the video world. It’s good to know that Slope (Contrast), Offset ( Exposure/Brightness/Setup), Power (Gamma) and Saturation, taken together are the most ‘’orthogonal’ control dimensions in a colour grade; this can help you choose what tools are best suited to perform your grades.
Now, if there are problematic naming conventions in FCPs various colour tools, one shouldn’t panic. As is the case for Avid, there are legacy reasons for the naming conventions to be messy. What matters is that you understand which parameter does what to your image. In time, as the industry evolves, Apple will be in a position to ditch the old names and abide by a more coherent standard.
(Ref. Poynton, Charles. “Digital Video and HD”. 2012 Elsevier; Tooms, Michael. “Colour Reproduction in Electronic Imaging Systems”. 2016 Wiley; Giorgianni, Edward. “Digital Color Management – Encoding Solutions”. 2008 Wiley)
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
Thankfully, folks from the ProApps team will be at the next LACPUG meeting – so we can maybe ask them directly if they have any guidance on this.
Things do change – if slowly.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
I totally respect that misimpression was never your intent, Simon.
Sadly, the web beast has a process of its own.
Everywhere I go online today in the X community, I see posts sbout how the FCP X new color grading is “broken” or “sub professional” or “needs bug fixing, stat.”
The fact that the follow up posts from the smartest practioners tend to challenge the simplicity of that assessment, barely matters.
The web doesn’t care. The narrative is set.
The teeming editorial masses have their headline to chew on. Screw the actual harder technical analysis.
IS it actually “broken?”
Or just “different?”
How do you tell anymore?It’s the new reality. Whether we like it or not.
PR has now morphed into PI.
Public relations sat between the manufacturer and the press who’s job it was to help interpret with experience and wisdom the truth of the sellers claims.Now sowing distrust is simply this eras MOST effective strategy.
In Politics, in Marketing – ANYWHERE there’s a competitive buck to be made.
The charge is on page 1 – the technical retraction on page 30.That “road to success” lesson was forged in politics – now it’s everywhere.
FIRST make people concerned or worried – THEN you’re more likely to change their behavior.Our new world.
Happy new year.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
Typical modern internet kerfluffle.
People see something that doesn’t conform to their expectations – and the wild speculation and fantasizing begins.
This reminds me EXACTLY of 2011 when X was released.
The traditional users went all “hair on fire” screaming about how Apple had made a huge tragic mistake and ruined professional editing.
Of course they hadn’t. Just produced a new version of it that had different utilities and functions for a new type of editorial thinking.
This may be precisely in the same tradition.
Maybe it’s the Rec2020 thing Simon and Oliver are discussing.
Maybe it’s Apple looking at and reimagining how grading could be simplified and improved for a changing industry where for every theatrical movie, there’s 10,000 internet videos delivered.
The only thing I know for sure is that for 30 years now when I’ve put my faith in Apples technical development vision, the resulting ratio of hits to strikeouts has been excellent.
So I’m still willing to put my personal productivity bets there, happily.
Already this thing that started out as “Apple Screwed Up!!!!” – is rapidly backpedaling into “Apple has approached the need for modern color grading somewhat differently.”
The last time they did that, my life got easier – and I started making more money with less effort.
I’m OK with that.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
Mathieu,
You are missing the point.
2011-2017 The Color Board was the Devils handiwork and Completely unprofessional.
Now it’s 2018 and since Apple has added Color Wherls and Curves – it’s THOSE that are unprofessional and the Color Board is righteous and true.
Get with the narrative!
(Obviously teasing)
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
I can do a VERY general summarization
Some professional colorists are disappointed that the new Tools in X are not ideally ACES or other standards compliant – tho they note that X’s competitors are generally in the same boat. The thread noted that AVID and Premier, even with Lumetri added – have holes in their approaches to grading that dedicated colorists will find lacking.
Resolve wasn’t mentioned in the referenced thread – so I don’t know wether or not Resolve colorists feel they have absolutely everything they need “in Suite.”
I’d suspect it’s much closer due to it’s heritage as a bespoke grading tool in it’s prior lifeIf you want to do your grading inside X – you can get closer if you deactivate the “Preserve Luma” checkbox in FCP X. After after step, apparently, it’s curves adjustment functions will be fully industry compliant, but the color wheels may still get you in technical trouble if used improperly. (this is my reading of things, to be taken with a grain of salt.)
Bottom line, for the legions of FCP X editors who do not wish to take on grading at a professional level – the new color tools are a great addition.
For those who wish to be both editors AND top ranked colorists and work in one program – there are still holes in ALL the current popular NLEs (Resolve perhaps excepted?) that can only be addressed by turning to bespoke tools.
That’s my takeaway, at least.
Others who know more can weigh in on anything I might have gotten wrong.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
First off, trust me, you don’t want to look to me for ANY information on color science. I’m clueless beyond the rudimentary practical knowledge I use for getting my exports “viewable” – and claim nothing else.
But I did enjoy reading that public discussion about how X handles color science when the new FCP X color tools arrived with 10.4.
It went in way more depth than I could ever summarize here – (and I’d likely get many details wrong through ignorance as well!) but since they were public posts, I suppose it’s fair game to copy and paste the most informative of them to you in a private email.
That might help you form specific questions that you could bring back here in the hopes that others more knowledgeable than I might take things further for you.
Keep an eye on your email.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
Happy New Year, Simon.
This kinda got hashed out 2 weeks ago on the 28,000 member Final Cut Pro X Editors Facebook Group.
The thread was started by Radim Řezníček under the heading…
The color management tools inside FCPX or when two do the same, it’s not always the same…
Some serious color professionals weighed in and the conclusion appeared to be that while some of Apples choices might not be absolutely optimal for some professional colorists accustomed to truly bespoke tools – the new tools are an excellent enhancement to the software. (And it’s obvious that no FCP X editor will quibble at the new capabilities price! )
You might want to stop by there and read the thread. Somebody named Phil Pan participated and it appears he’s a top tier color science guy working in or near Hollywood on big $$$, mission critical stuff.
Might help anyone interested in the new FCP X Color tools to better understand Apples approach.
FWIW.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
[Shawn Miller] “How do you know that my non-editorial software is less efficient? Don’t you routinely criticize non-FCPX editors for commenting on software they’ve never used?☺”
Fair criticism, I suppose – but it’s based in the fact that I do have a casual acquaintance with some world class coders – who tell me that some long time software (they mentioned AE in particular) has a lot of legacy code that’s not particularly efficient doing things like still calling the CPU for tasks that would run a lot more efficiently on the GPU – one factor that makes it somewhat inefficient compared to more modern programs.
I think the general coding term is “cruft” – old inefficient code that complete re-writes like X did in 2011 and Resolve continues to write afresh – tends to eliminate.
But you’re right. I’m not a programmer and I have no real expertise in the area. .
It does make sense however that long running software that attempts to maintain every single feature users have become accustomed to over decades – might do that at a price regarding efficiency.
But I could be totally wrong.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery. -
[Shawn Miller] “And that’s great for FCPX editors… but it doens’t have anything to do with my answer to Greg’s original question. If a computer has the hardware I need to get my work done more quickly… I don’t care what it looks like or who makes it.
“Then you answered your own question, even if you’re unwilling to acknowledge it.
If EDITORIAL is a significant part of your work – you should add a Mac and FCP X to your toolkit. Because that’s the hardware and software combo that “edits” the fastest right now.
Of course you’d have to learn to use the software efficiently – which takes effort.
Adding “other software” to the mix is certainly a rational reason to sticking with a PC – but you have to accept that you’re hobbling your editorial tasks, just for access to the greater horsepower required for running less efficient non-editorial software. So you’re just picking one compromise over another. Which is fine. But for how long?
As we saw with FCP X – tearing down a legacy program is a big risk. But a few years down the road – when those performance gains prove to be very significant – it’s one really good way to keep the efficiency curve ascending.
Hard choices.
Creator of XinTwo – https://www.xintwo.com
The shortest path to FCP X mastery.