What Are The Origins of Post-Production’s ‘Gamma Wars’?

The Apple LaserWriter Print Dialog Box

Is THIS the start of the Gamma Wars? From the original QuickDraw Manual.

A few weeks ago I put a link into the Sunday Newsletter about a 2014 BBC White Paper on High Dynamic Range video. It’s a dense but fascinating read, partly because the Introduction does a nice job comparing modern camera sensors to the capabilities of the human eye. It also has an interesting discussion about the influence of CRTs native response on the choice of video’s ‘2.4 gamma curve’. In the summary of Section 2:

for many years the dynamic range of television displays was limited to about 100:1 by CRT technology. A non-linear “gamma” curve was used to equalise the effect of noise at different brightness levels in analogue TV systems. 

Elsewhere the White Paper discusses the non-linear “gamma” curve in CRTs:

Early television engineers took advantage of the non-linear characteristic of CRT displays to achieve [uniformity of noise], since the non-linearity of a CRT closely approximates a power law of 2.4

In other words CRTs were used because their native gamma response (nearly) perfectly matched their needs for natural-looking video images. Then, flat panel technology came along:

With the advent of digital TV the same gamma curve also allowed video to be quantised to 8 bits without significant contouring.

As the White Paper explains: At 8bits and above there’s sufficient narrowness between each step of brightness that the eye (usually) can’t see artifacts when using the same “gamma” curve as CRTs. Our Engineering Overlords declared the technology sufficient, 8-bit the minimum requirement for television delivery but they never thought to explicitly define the “gamma” curve—since we hadn’t yet entered the age of digital displays.

What happened on the computer side of video displays?

Why didn’t computer displays match video displays, especially since the early computer displays were CRTs?!? To answer, I put on my Google Gloves and this blog post from 2006 popped up, The Gamma Question: 1.8 or 2.2?

the standard CRT monitor built into the Mac wasn’t anything special either, still having a native gamma somewhere near the 2.5 mark. . . Apple specified how their QuickDraw graphics libraries recorded pixel values to pull the native gamma of the monitor down to 1.8. This made it so that a user adjusting an image on the Mac monitor created pixel values recorded by QuickDraw that printed as a reasonable match to the monitor image. This worked so successfully in fact that the 1.8 gamma became regarded as the gamma of the Mac monitor itself

And what were Apple computers matching their CRT display output to?

Freaking Black & White LASER PRINTERS.

Apple. Broke. the CRT. On purpose. To match QuickDraw to the printed page.

And thus began the Gamma Wars

Yes, I heard this story many years ago and still, forgive me if I can’t stop laughing. Apple has had an over-sized impact on our industry for MUCH longer and in ways than most of us realized.

Friggin’ QuickDraw. Crazy how this stuff happens, right?

– pat

Comments { 0 }

Podcast: Flanders Scientific Part 3

“The Future of Reference Monitors”

Bram Desmet – CEO and General Manager, Flanders Scietific

Bram Desmet is the CEO and General Manager of Flanders Scientific, Inc., based in Georgia just 30 minutes outside of Atlanta.

Despite holding a B.A.in Philosophy from GA State University – and being an instrument rated airplane pilot – Bram ultimately followed in the footsteps of his father, (a 30 year veteran of the professional broadcast industry) when he joined DDA (a sister company of FSI) and then later Flanders Scientific. Both companies focus heavily on professional display technology.

As Managing Director at Flanders Scientific Bram is a vocal advocate of FSI’s core philosophy of providing professional broadcast products that strike an ideal balance between performance, features, and affordability.


In Part 3 of Bram’s Interview we discuss:

  • What is Rec. 2020?
  • Are there devices that can display the Rec. 2020 color gamut?
  • 4K Displays: How widely manufactured? How about true 4k vs. UHD?
  • The problems with high-performance 4K displays

Questions answered from LiftGammaGain:

  • What are the factory settings of FSI displays when they ship to the customer?
  • Do we need to recalibrate if we switch off the factory settings?
  • Why is the 17″ OLED more expensive than the 24″ OLED?
  • How to get better audio sync between SDI video and analog audio monitoring?
  • How to set the output of your camera to minimize audio delay
  • Will FSI allow ‘live grading without a LUT box’ on their displays?
  • Will there be a Mac or PC app for quick LUT loading on an FSI display?
  • Are there scaling artifacts we need to worry about when monitoring 4K material in 2K mode?
  • Do FSI displays clip out-of-gamut data?
  • Finally, there’s the ‘peanut gallery’ question (thanks Paul Provost)!

This podcast was edited by Tom Parish out of Austin, Texas. Visit him at TomParish.com.

Tweet, Like, or Leave a comment! (bottom of the page, no registration required)


Listen Now

Part 1 | Part 2 | Part 3

Subscribe in iTunesSubscribe to the Tao Colorist Sunday Morning Newsletter
More Interviews


Show Notes (links open in a new window / tab):

This interview is part of an on-going interview series with the movers, shaker, and thinkers involved in the field of professional color grading for moving images. When I have new episodes to release, they are released on Tuesdays. To be notified you may follow me on Twitter (@patInhofer), via our RSS feed, and on iTunes.

You can find more interviews here: TaoOfColor.com interview series homepage.


FCC Disclaimer
Yes, I have affiliate accounts with online retailers. Anything on this page that links to Amazon, B&H Photo or ToolFarm is  an affiliate link. If you buy anything from my affiliate link not only do I get a commission, but you get a warm pleasant feeling that you’re helping to sustain the Tao Of Color website! If that is what you do – I, and all my readers and listeners say, Thank You.
Comments { 0 }

SMPTE-NY Meeting: Live Blogging “Evaluation Grade Monitoring”

Feel free to discuss this post in the comments!

This past Thursday, SMPTE-NY had a joint meeting with the IEEE and SID-MAC. The topic “Evaluation Grade Monitoring for Cinema and Television”.

In truth, most of the discussion was on Television monitoring. In a separate room was the Dolby PRM-4200 Reference Monitor, a 20-series Panasonic plasma, and (3) Sony displays sitting side-by-side: BVM 24″ flat tube CRT, the new 25″ OLED in the middle, and their 24″ BVM LCD.

Before I get to my notes, some quick impressions on the displays I saw:

  • Dolby PRM-4200 LCD: This $50,000US LCD is a monster. When I first walked into the room I though someone had rolled in one of the old flat screen 40″ CRTs or a rear-projection set. That said, it’s a great looking LCD. And listening to the Dolby presentation I got a sense as to why it’s so expensive. For one, it natively displays the full DCI P3 gamut. Dolby goes through a meticulous process to hand-select panels that can meet this spec. Second, the blacks are very very impressive. Third – the darn thing can output (and, IIRC, maintain grayscale linearity) up to 600 Nits to emulate a typical home display (in comparison, most reference monitors are calibrated between 100 – 200 Nits).  But again – if you need to take this thing with you on-set, it’ll take three men to move it.
  • Sony OLED: This is an impressive monitor. One piece of footage they were running was a long 3 minute wide shot of cliffs over water as the sun sets. The deep shadows in the OLED held detail long after the LCD was overwhelmed by the (dim) ambient room light. And in the Sony presentation it was clear, though not explicitly stated, Sony considers this their Grade 1 reference monitor – knocking their LCDs off that pedestal.
  • Panasonic Plasma: The pro-sumer 20-series they displayed was calibrated to Rec. 709 gamut. Like the OLED, it’s just fun to look at. As I’ve written in my notes, they don’t consider the LCDs to be Grade 1 reference monitors for color critical decision making. They also don’t consider their Plasmas to be in that class either – though they think they make fine client monitors since they can be calibrated very closely to Rec. 709. The big issue is how plasmas need to cut the power in extremely bright scenes (think: standing in front of a white cyc). A reference monitor needs to maintain brightness throughout the grayscale.

Some other general observations:

  • This was a very technical crowd of around 60 -100 people. One speaker asked colorists to raise their hands, and I think maybe 3 hands went up. Lots of engineering types in the room.
  • Green phosphors – in general, displays have trouble getting saturated greens to meet the wider gamuts. This seems to plague all the display technologies.
  • There was lots of talk about modern displays not just meeting the specs of CRTs (which had lots of problems) – but going beyond them.

Notes of importance:

  • It turns out that CRTs never had an explicit standards for image display (peak white level, gamma response, etc). The phosphors were standardized, but nothing else since CRT technology had inherent characteristics that were difficult to change. If you were building a CRT and used SMPTE phosphors there wasn’t much else you could do to the image. Today, that’s all changed and nothing matches CRT, or each other. Standards and Recommended Practices are currently being developed.
  • There’s controversy over what should be a “Specified Standard” and what should be a “Recommended Practice”. I think my notes cover it pretty well.

Read On for my notes from this meeting… and feel free to comment at the end of this post.


————

“Evaluation-Grade Monitoring for Cinema and Television”

Thursday, February 24, 2011

6:30 PM Program Begins

Produced by Mark Forman, Mark Forman Productions, Corp.

No more CRTs! What to use for a reference display? Join us for a technical discussion on the future of evaluation-grade monitoring in the post-production environment for digital cinema and television.

Speaker

David Bancroft: Bancroft Technical Consulting, IEEE BTS Distinguished Lecturer and Chairman of SMPTE’s Fixed-Pixel-Matrix Display Working Group

Laryngitis

Why standards?

  • Interchange & interoperability : consistent results, across a range of suppliers. Suppliers have a common spec to target. Consumers get the possibility to get a consistent viewing experience.

Monitor vs signal standard:

  • recorded signals have specified standards, monitors don’t. CRT didnt need specs due to the technology – operated in a narrow range.  NOW we need standards since current displays don’t natively match CRT – they used to be deficient to CRT, now they are excessive.

Reference monitor:

  • Calibrated measurement tool. 1 volt needs to equal 1 volt. Measuring appearance to reveal content we are adjusting, lighting, exposure, color balance, & balance between camera angles, scenes, even if it doesn’t reflect reality. It must “tell the truth, not just pleasing”. Pleasing is for consumer sets.

What we need:

  • Same content looks same on every reference monitor and should never looks like it needs to be remastered in another facility.. No serious change in appearance with new tech vs CRT mastering.

What Manufacturers need:

  • Ref monitor that should be capable of meeting standard and must have the data to measure.
  • May have to set standard to a higher black level that the monitor can attain so operators can actually calibrate. Blacks in OLEDs are literally black – how do you measure pluge?

Standards are codified and should be practical, realistic

Recommended Practice are suggestions

They need to cover things we can control: Inherent properties of the monitor, inherent properties of the viewing room, controllable properties of the monitor, controllable properties of the viewing room.

The following is personal opinion of speaker about how they should be divided:

  • Standards are the things the User can’t control in the Monitor and viewing room. These are inherent properties.
  • Monitor inherent – gamut limit, intensity range from black to super-white @ color temp, contrast range, pixel counts (spatial response) and 1-to-1 pixel mapping mode (no scaling); temporal response (how quickly can it refresh for acceptable human vision); viewing angle (max allowable variation in luma and color in horizontal and vertical) & surface reflectivity
  • Viewing inherent. -  Max low level light ambient light; reflectance of surfaces on walls.

Recommended Practice:

  • Things easily controlled by the User
  • Monitor setup: engineering setup, operational setup (quick calibrations)
  • Viewing: ambient light, monitor surround (10% of peak white?)

Current status of specifications –

  • EBU revision – April 2011 tech document 332o. It’s a USER requirement
  • ITU has group working on gamma
  • SMPTE, 2008 Study group is now Working Group, 2011Q2 / 2011Q3 for monitor inherent standard; 2011Q4 for viewing inherent; then Recommended Practices in 2012

Audience Question: Shouldn’t we go for more colors and wider gamut rather than be restricted by what CRTs could reproduce?

Answer: We need to agree on incompatibility between old and new content. Not a technology problem, requires more bits, maybe noisier pictures.

Call for User Input on SMPTE panel

————

Speaker

Pete Putman, ROAM Consulting, Display Consultant, Educator and Columnist

Suitable CRT Evaluation Replacements:

Display wide grayscale at consistent over time

  • LCD transmissive, like light shining through window blinds – white crush is problem and is non-linear at very top of response curve
  • Plasma, emissive, like staring at sun (my comment, not speaker’s)
  • OLED, emissive : low yield, two types SM OLED & P OLED
  • FED, killed by lawyers

CRT Replacement must :

  • track color consistent
  • neutral gray
  • wide viewing angles
  • calibrate to standards
  • wide grayscale without clipping or crushing

Accurate gray scales are the key. Shadow detail is toughest. false contouring

LCD – CCFL are tough to track. Color accuracy is problem (especially greens due to added blue phosphor)

Plasma – False contouring is not a problem

Plasma Vs LCD

  • Wider viewing angle – especially up/down axis
  • can match 709 and most of DCI
  • full white drops with power management dropping light output (from 100 nits down to 65 nits)
  • High switching rate (up to 600 Hz)
  • Phosphors age (usually in first 200-300 hours).

LCD v Plasma

  • Polarizing is a problem and reduces viewing angle
  • Led backlights help reduce blacks
  • green can be undersaturated – blue red hits 709 and DCI, green 709.
  • IPS tend to look better.
  • Pro monitors moving to LED backlighting, doesn’t solve viewing angle.
  • Motion blur can be problem.
  • Put up grayscale and move around to test off axis viewing issues.

Panny TH-42PF20U Plasma

  • Covers Rec.709, most of DCI,
  • gamma just barely off and fixable (especially using something like Davio),
  • grayscale track is good as good as many CRTs
  • 120-129 nits, 931:1,
  • nice deep blacks.

Waiting in the wings – OLED, SM OLED is current favorite. High current Low voltage,

LEM-150, 15″, $6k,

  • gamut maps 709 nearly precisely
  • not suitable for P3
  • nice gamma response
  • grayscale track is flat
  • error better than many eval. displays.
  • no viewing angles issues.
  • 100-120 nits
  • 140,00:1
  • black level .001 nits. Beyond range of testing device

————

Gary Mandle, Senior Product Manager, Sony Electronics Inc.

OLED Eval Monitors

Started in 1994, first showing in 2001, 2004 small OLED

$203 million plant just for OLED

First pro OLED was 7″ and now 24″

Simple process, tough execution (process didn’t seem simple to me)

Explained science of OLED

  • Low energy
  • uses phosphors
  • entire panel is 1/16″ thick (some layers are less thick than a water molecule)

To get to P3 gamut they block low energy emissions and enhance high energy emission (esp. in green channel) to get expanded saturation.

Several different OLEDs : Stacked, transparent (HUDs), PLED (flexible), active matrix (that’s the reference OLED)

OLED beats CRT at

  • contrast
  • low light
  • black performance is whatever you want it to be
  • pixel speed from white to black is nearly instantaneous, have to slow it down because the speed produces flickering
  • tuned to balance smear vs flicker

OLED gamut accuracy from black to white, LCD loses accuracy near blacks.

Building 17″ 25″ panels. 10 bit, P3, surpassed CRT life 30,000 hours (failure is sudden toward yellow), 12 bit hdmi, display port

Half weight of LCD

2k for cinema, displays interlace (1080i), plugin card for Harris rasterizer

Burn in can be problem, same as CRT but not any worse, auto shutoff after 10 minutes

72 watts, no fans, no heat problems,

Headroom over 200 nits

  • It measures color balance and luminance to keep panel stable as phosphors decay, using the headroom to slowly compensate for phosphor decay. When it can no longer compensate it does a sudden failure. You ‘ll know it!

———–

Steve Mahrer, Senior Technologist, Production and Media Services, Panasonic

If we replace CRT, don’t just emulate, improve – CRTs were not quite 709

Ideal CRT replacement

  • high res (2k and beyond)
  • great Scaler for non native resolution (don’t introduce artifacts)
  • 1:1 pixel mode
  • user controls for gamut / gamma management
  • good off axis viewing
  • “native” options
  • no 120hz 240hz
  • Bigger is better – content errors missed on 19/ 25″ devices are fully visible at 50″
  • 3d capable? Probably.
  • affordable

Panny Plasma

  • black not quite OLED
  • good gamma especially with LUT management
  • green phosphor decay has been fixed for 3d and looks great in 2d – especially in next generation 30-series plasmas
  • 80% P3

Panny LCD

  • CCFL
  • better than 709
  • LUT presets for 709 601, EBU
  • At best are probably Grade 2 devices

Panny DLP

  • large venue
  • high contrast
  • accurate
  • great for film outs as cinema display.

25″ vs 50″ size reveals issues

In 2 years all plasma will be 3d for cost of 2d

Panny 42″ 50″ 65″ will all be 3d later this year

At NAB releasing 30series

  • better blacks closer to reference

Don’t make smaller than 42″ Plasma since it tough to make pixels small enough

No announcement about OLED.

Floating white points on Plasma at >130 nits can be better controlled, no comment on when it’ll happen.

————-

David Schnuelle, Senior Director, Image Technology, Dolby Labs, Chairman of the SMPTE Digital Cinema Technology Committee

PRM-4200 Refernce Monitor

  • better than CRT
  • Fixes CRT deficiencies
  • Dark blacks
  • built in 1d 3d LUTs
  • Rec709, P3 (and more)

It’s all about Math – digital processing to model the standardized display

10 bits not enough anymore – Image Interchange Format is 16 bit OpenEXR over 12bit log.

Dithering needs to be removed

Can match consumer brightness. (500 – 600 nits)

How do you do your initial passes without being in the Big Room? Must meet P3 , not a simulation.

10 bit outputs need 12 bit displays

1500 x 3 = 4500 individual RGB LED, 10 bit no dithering,

Balloting finishes on proposal for math to turn electrical impulses into an image on the screen next month

Characterize, calibrate in factory, compensate

Getting accurate color readings at low levels is very difficult and EXPENSIVE

LCD LED life testing. 50,000 hours stay within 1% of their spec.

LCDs are individually qualified because of getting to P3 (mostly in green channel). Primary and white color accuracy better than most CRTs they’ve measured.

  • .005 nits for black. They tend to ride it higher – If they lower it expert viewers complain
  • 2.4 gamma
  • peak deviation are minimal
  • color tracking highly precise

Low reflectence

$1k / inch @ 50 inches !

——-

That’s it!

Discuss in the comments…

Comments { 0 }

Joe Owens Interview, Part 2

“The Banker’s Pass – with a Dash of Tobasco”

Joe Owens is the Owner / Operator of Presto!Digital Colourgrade, located in chilly Edmonton, Canada.

Joe Owens

After getting his start as a camera shader over 30 years ago and now a full-time colorist for over 17 years – Joe’s a well-established presence in his Edmonton market. But his influence is felt around the world – as the leader in the Apple Color forum helping ‘newbies’ (and well established professionals) negotiate the delicate balance between technology, art, and business.

He recently finishing color grading 2 documentaries for the CBC network,  12 1-hour episodes of “Blackstone” for APTN / Showcase HD and 12 episodes of “Pet Heroes” for CMT.

Yes, Joe’s a busy guy.

Joe was kind enough to spend some time with me in my New York office (with sirens and horns) and share his experiences and thoughts of moving from the early days of analog videotape to ‘big iron’ telecine to non-linear digital color grading systems.


In Part 2 of Joe’s Interview we discuss:

  • The original “Final Touch” 2k grading app
  • The “Dark Art” of color grading
  • Colorist ‘thumbprints’
  • Joe’s favorite colorists
  • Creating ‘looks’ in the early days
  • Working with plug-ins & presets
  • When is “good enough”
  • Getting consistent in your grades
  • Client workflows
  • Joe’s office setup
  • Creature comforts
  • The physical setup of a colorist and the client
  • The 3 pillars of color grading
  • The impact of desktop color grading tools
  • How to know when a client is *your* client
  • The business mindset
  • Final comments on the layout of a grading suite

Tweet, Like, or Leave a comment! (bottom of the page, no registration required)


Listen Now 

Part 1 | Part 2
Subscribe in iTunes | Subscribe to the Tao Colorist Sunday Morning Newsletter
More Interviews

Show Notes:

This interview is part of an on-going interview series with the movers, shaker, and thinkers involved in the field of professional color grading for moving images. When I have new episodes to release, they are released on Tuesdays. To be notified you may follow me on Twitter (@patInhofer), via our RSS feed, and on iTunes.

You can find more interviews here: TaoOfColor.com interview series homepage.


FCC Disclaimer
Yes, I have affiliate accounts with online retailers. Anything on this page that links to Amazon, B&H Photo or ToolFarm is  an affiliate link. If you buy anything from my affiliate link not only do I get a commission, but you get a warm pleasant feeling that you’re helping to sustain the Tao Of Color website! If that is what you do – I, and all my readers and listeners say, Thank You.
Comments { 3 }