● What is the history and background of the auto cal feature? 
 
○ With the launch of our 2016 OLED products, we started receiving requests from  professional content creators who were buying our OLED TVs for use as  reference client monitors. They were happy with the product, but wanted to know  if we had any tips for calibrating. This started an ongoing collaboration with a  number of content partners to improve the accuracy of our displays, some of  which was implemented in our 2017 consumer TVs, though without the  automated feature. 
 
○ During 2017, we started beta testing with our professional partners, the auto  calibration in the form we introduced at CES 2018. At that time, we were the first,  and probably still are the only CE company to offer hardware level access to the  image processing functional blocks in our TVs, offering unparalleled flexibility and  accuracy. At CES 2018 we were honoured to receive a ‘Best of CES’ award from  AVS Forum for this feature.    ○ After the success of our 2018 auto calibration feature, we started looking at how  we could further improve functionality for 2019 products. We’re pleased to  announce three new features that build upon the 2018 functionality and address  the cost ‘barrier to entry’, as well as providing flexibility in configuration and  usability improvements.    As in 2017 for our 2018 products, the feedback we received from beta testing  with our content creation industry partners over the last year has directly  influenced the new 2019 features, and we’re very grateful to the partners we  have worked with to achieve this. 
 
● What’s new for 2019? 
 
○ For 2019, we’re introducing 3 new features / changes over the 2018 auto  calibration implementation. 
■ Integrated Test Pattern Generator (iTPG) - Reduces the barrier to entry by  at least $1,500 
■ HDR10 Tone Curve Parameters - Provides the ability to set the HDR10  tone mapping to match the measured peak luminance of the display and  adjust the roll-off point for 3 definable metadata points 
■ Picture Mode Reset Behaviour - Allows individual picture modes to be  reset to factory status after an auto calibration, removing the need to do a  full factory reset loosing all calibrations for all picture modes as was the  case in 2018 
 
● What are the capabilities of the iTPG, and how is it different from an HDMI TPG?   
○ The iTPG has the potential to result in increased accuracy over an external TPG  for the following reasons: 
■ It operates at 10-bit precision, with CalMAN able to make full use of this  precision 
■ It operates in RGB space, and is therefore not subject to the potential  errors from RGB to YCbCr conversions such as rounding errors and / or  incorrect matrix co-efficients   

○ The iTPG operates in 10-bit Full Range RGB space, and has the following  capabilities: 
■ 3840 x 2160 native resolution 
■ 10-bit precision RGB 
■ Up to 10 different boxes can be defined at arbitrary sizes and positions (a  typical 10% area patch is, for example, two boxes; 1 full screen black, and  1 10% area for the patch) 
■ Up to 4 Gradient ramps running horizontally or vertically, with definable  start RGB value, step size (in RGB value) and spacing (in pixels)   

○ The iTPG is positioned in the video pipeline after the HDR processing, and after  the Brightness and Contrast controls, but before all of the LUTs used for  calibration.   
○ Brightness and Contrast adjustments are a legacy function that is often  misunderstood. In theory, these controls should never be used or needed with  digital signals, and they should not normally be used when using the auto  calibration feature because the functions they provide are more accurately served  by making changes in the 1D LUT.   

The location of the iTPG means that any changes made to Brightness and  Contrast will not have any effect on the iTPG patterns. Any changes from the  default settings for Brightness and Contrast (50 and 85 in SDR; 50 and 100 in  HDR respectively) will make an auto calibration using the iTPG invalid.    

Note:​ Changes to the Brightness and Contrast from default will also cause a 1D  auto calibration using an external TPG to fail, for related, though not identical  reasons.   

○ The iTPG can be used for SDR, HDR and Dolby Vision calibration, but cannot be  used to validate HDR and Dolby Vision calibration in PQ space because it is  located after the HDR tone mapping, once the signal is in Gamma space. 

■ It’s important to understand that up-stream HDR processing is not  something that gets calibrated, and is simply maths. LG would encourage  journalists to test this (using a traditional external TPG to validate an iTPG  HDR calibration), but if the iTPG calibration result is good, it is safe to  assume that the HDR and Dolby Vision calibrations will also be good, even  though they cannot be validated with the iTPG   

○ As with an external TPG, it is necessary for the TV to be operating in SDR mode  to perform an SDR calibration, HDR mode to perform an HDR calibration, and  Dolby Vision mode to perform a Dolby Vision calibration. With an external TPG,  this is achieved by setting the output mode of the TPG. With the iTPG however,  there is no equivalent setting.   

It is therefore necessary to ensure that a video of SDR, HDR or Dolby Vision is  playing as needed. This can be achieved using an external video source like a  Blu-ray Player, but the easiest way is to play a video file using the USB file  playback support of the TV. LG has therefore provided 3 test videos that simply  play 1 hour of 15% stimulus full screen grey in SDR, HDR and Dolby Vision. 

These files can be downloaded here: 
■ SDR - ​https://lgtca.box.com/v/SDR 
■ HDR - ​https://lgtca.box.com/v/HDR 
■ Dolby Vision - ​https://lgtca.box.com/v/DoVi   
● How do the HDR Tone Curve Parameters Work?   

○ LG has provided 7 parameters to adjust the HDR-10 tone mapping behaviour  when Dynamic Tone Mapping is disabled: 
■ Peak Luminance - Used to set the target output luminance range for tone  mapping calculations; set to measured panel peak luminance to track PQ  accurately 
■ Tone Curve Metadata Point (x 3) - Used to define which content metadata  peak luminance value you’re defining the tone curve for 
■ Roll-Off Point (x3) - Used to set the point at which the tone curve deviates  from PQ, expressed as a percentage of the Peak Luminance value   

○ With the 3 Metadata and Roll-Off Points, it is possible to accurately define tone  curves for content with 3 specified metadata points (e.g. 1,000 nits peak content,  4,000 nits peak content, and 10,000 nits peak content); content with peak  luminance metadata between these points will result in a tone curve that is  interpolated between the three defined points.   

○ If a PQ Hard Clip is desired regardless of metadata sent, such as for content  creation purposes, or to use the display as a PQ reference, this can be easily 
achieved by setting all three Roll-Off Parameters to 100%.   

○ If content metadata signals a peak luminance lower than the Peak Luminance  Tone Curve Parameter, a Peak Hard Clip tone curve will be used, tracking PQ up  to the Peak Luminance Tone Curve Parameter and clipping content at higher  luminance.   

○ LG TVs determine the PQ Luminance of content for static tone mapping as  follows:  
■ Use ST.2086 Mastering Display Peak 
■ If MaxCLL is present ​AND​ lower than ST.2086 Mastering Display Peak,  use MaxCLL 
■ If ST.2086 Mastering Display Peak and MaxCLL are both signalled as zero  (as defined for un-available), assume a peak luminance of 4,000 nits   
● How does CalMAN make use of the Tone Curve Parameters    ○ CalMAN features a new section in the DDC panel for entering the 7 parameters  and an upload button to send the data to the TV. Workflows will be updated to  walk users through this process   

○ CalMAN has full information on the maths used by LG TVs to create tone curves  based on the 7 parameters and can therefore use this to update the target EOTF  in their software. If this is done, rather than checking the dE against PQ, which  shows errors as tone mapping inevitably causes deviations from PQ, CalMAN will  now only show errors as the display deviates from its intended, defined by Tone  Curve Parameters EOTF.   

● Is it Possible to only change one of the 7 Tone Curve Parameters?   

○ No, all Parameters must be sent if any one of them is changed. Having said that,  the default values for all 7 are known by CalMAN and it is possible to change only  one of the values and then send the other 6 as the defaults.    

○ For reference, the default values are:  ■ Peak Luminance: 700 nits  ■ Metadata Point 1: 1,000 nits  ● Roll-Off Point 1: 70%  ■ Metadata Point 2: 4,000 nits  ● Roll-Off Point 2: 60%  ■ Metadata Point 3: 10,000 nits  ● Roll-Off Point 3: 50%   

● Which picture modes can be calibrated? 
 
Unchanged for 2019: 
 ○ SDR  ■ Cinema  ■ ISF Expert Bright  ■ ISF Expert Dark  ■ Technicolor Expert  ■ Game 
 
○ HDR (HDR10/HLG)  ■ HDR Cinema  ■ HDR Game  ■ HDR Technicolor Expert 
 
○ Dolby Vision  ■ Dolby Vision Cinema  ■ Dolby Vision Cinema Home  ■ Dolby Vision Game    ● What makes Hardware Level Auto Calibration different from competitor  implementations? 
 
○ Although auto calibration is not a common feature on displays, auto calibration  alone is not something new; many of our competitors have had auto calibration for  some time. What sets this implementation apart from past versions is a number of  significant features, but most importantly, direct hardware access to the functional  blocks in the TV processor (3D LUT, 1D LUT and 3x3 Matrix).  

■ This truly is revolutionary, because having direct access to these blocks  allows for the best possible calibration, rather than being limited to a low  number of adjustment points, or low precision or range of the controls. 
 
○ Additional differentiating features include: 
■ Secure, fast IP Communication (WiFi or Ethernet). 
■ 33x33x33 3D LUT size. 
■ The ability to calibrate multiple picture modes, including Game Modes. 
■ HDR calibration in Gamma Space rather than PQ or HLG (Validation is  done in PQ or HLG).   
● Why is calibrating HDR in Gamma Space beneficial?   

○ Although not obvious, all consumer (and almost all professional) display panels  produced today have a 2.2 Gamma native EOTF response. There are a number of  reasons for this, including the actual non-linear characteristic of the display  material (LCD, LED, OLED etc.), and of course history.    

○ As a result of the 2.2 Gamma native panel response, all TVs which support HDR  video inputs, must convert the incoming signal from PQ or HLG into 2.2 Gamma.  There are also no TVs produced today which can reproduce the full 10,000 nits of  a PQ EOTF signal, so tone mapping must also be applied.    

○ The purpose of calibration is to correct for panel variability, and correct for panel  behaviour that isn’t as designed. Tone mapping and conversion to 2.2 Gamma are  not calibration functions, they’re simply maths, but the output of this maths  assumes a perfect 2.2 Gamma panel with an accurate white point and a known  peak luminance.   

○ When LG TVs are calibrated using the Autocal function, the upstream HDR maths  is bypassed, and the 1D LUT and 3D LUT are created to achieve a result as close  to the perfect 2.2 Gamma with accurate white point that the HDR processing is  assuming.   

○ Calibrating HDR without bypassing this HDR processing maths is possible, but all  of the adjustments are taking place in Gamma space, even though your input is  PQ or HLG. If your panel peak luminance is higher or lower than the assumed  peak luminance of the HDR processing maths, you may find yourself pushing the  greyscale adjustments in odd directions to compensate, resulting in the potential  for banding. 
 
● How big are the LUTs that CalMan has access to? 
 
○ The 1D LUT is a 10-bit LUT (1024 points) at 15-bit precision. 
 
○ The 3D LUT is 33x33x33 in the Alpha 9 Gen 2 Chip (used on all OLED except for  the B9 series). 
 
○ The 3D LUT is 17x17x17 in the Alpha 7 Gen 2 Chip (used on all SK Series Super  UHD LCD TVs and the B8 series OLED). 
 
● Why does CalMan only make adjustments for a small number of points if there is  access to 1024 points in total? 
 
○ Obviously, measuring and adjusting 1024 points would take a long time, but we  have found through testing that it is simply not necessary to make that many 
adjustments. As long as the point that you are adjusting is exactly lined up with  the point that you’re measuring (which isn’t always a given by the way), and the  interpolation between points is sufficiently good, measuring additional points does  not increase accuracy. 

■ This can actually be seen when the autoCal process is running; often an  patch is measured, and no adjustments are made at all because the  interpolated LUT data at that point is already accurate. 

■ Another way to look at this is that displays, including OLED and LCD will  trend towards a certain neutral colour, rather than being, for example, too  blue at 10% and then too Red at 20%. It’s therefore understandable that if  you adjust 10% and 20%, and you interpolate the adjustment at 15%,  you’ll already be very close; and in our testing, we optimised the spacing to  take advantage of these trends. Multiple adjustment and measurement  point options are given though, so you do get a choice. 
 
● If CalMan is only adjusting ~20 points for grayscale, how is this any advantage over a  traditional 20 point grayscale adjustment? 
 
○ Traditional 20 point grayscale adjustment takes place at a ‘UI’ level, even though  the eventual hardware that will implement the changes is a hardware 1D LUT just  like we’re using. At the UI level however, there are multiple settings that will take  effect on the 1D LUT, such as: 
■ White point setting 
■ Gamma setting 
■ 2 point white balance (RGB Gain / Offset) 
■ 20 point white balance 
■ Factory white balance settings in the service menu 
■ Brightness & Contrast (indirectly) 
 
○ All of these settings are merged in an algorithm that also interpolates values  between settings and applies corrections for boosting contrast, lifting shadows  etc. The interpolation algorithm for a traditional 20 point 5% spaced greyscale  might be great, but there are so many other inputs that you may be fighting  against that prevent you from, or make it take longer, to achieve a good result.  An example of this might be that you want to target a white point of D65. The UI  setting for D65 is too red, and the cooler white point is way too blue. You select  the D65 setting because it’s closest, and use the 2 point or 20 point to remove  some red, but in this situation the factory calibration for the D65 UI setting had  already added red to achieve the factory D65 white point. That setting is adding  red and you’re removing red; two UI settings fighting one another! With direct  LUT access, all of the UI settings, including even the factory calibration settings  are all bypassed, and the LUT data is directly manipulated. 
 
○ SpectraCal has worked hard through testing to optimize the number and  distribution of the adjusted points, rather than simply adjusting at 5% intervals as  is traditionally done. 
 
● What is a 1D LUT? 
 
○ A LUT, or ‘Look Up Table’ takes an input value, and outputs a different value from  the data in the LUT. An example would like like this: 
 
Input  Output 
0  0 
1  3 
2  7 
3  9 
4  12 
..  .. 
 


○ A 1D LUT can only make changes in a single dimension. For a TV, the  ‘dimensions’ that the data is in are R, G and B, so what this means is that any Red  input value can be mapped to any Red output value. A 1D LUT is typically very  accurate, because there isn’t much interpolation, if any, needed between points,  but a 1D LUT does have limitations because it’s only working in a single  dimension - see ‘What is a 3D LUT?’ for more details. 
 
○ There are typically 3 x 1D LUTs in a TV, one for each Red, Green and Blue. 
 
○ 1D LUTs are typically used for grayscale / white point and gamma adjustment,  and they’re ideal for this because their limitations aren’t relevant at this point in  the video path. 
 
● What is a 3D LUT? 
 
○ A 3D LUT is similar to a 1D LUT in that it is a table with a list of input values and  output values. It differs significantly in that it operates on three dimensions,  typically R, G and B. 
 
○ Whereas a 1D LUT will look at only a single input value (single dimension), such  as map Red input 3 to Red output 9 in the example above, a 3D LUT will look a an  RGB triplet, effectively mapping any input colour to any output colour. 
 
○ 3D LUTs are far bigger than 1D LUTs, and it is extremely rare to see a 3D LUT  implemented without any interpolation required. A full (no interpolation) 1D LUT  for 10-bit RGB would be 3,072 points (3 x 1,024) A full 3D LUT for 10-bit RGB  would be 1,024​3​ = 1.07 billion points! 3D LUTs are therefore implemented at  smaller sizes and interpolation is used to re-map colours between these points. 
 
● What are the differences, from a calibration perspective, between the Alpha 9 Gen 2  Chip and the Alpha 7 Gen 2 Chip? 
 
○ The Alpha 9 Gen 2 features a 33x33x33 3D LUT, whereas the Alpha 7 Gen 2 has  a 17x17x17 3D LUT. Functionally these operate in the same way, but a  33x33x33 3D LUT allows for less interpolation.    ○ The Gen 2 versions of LG’s TV SoCs are obviously based on the first generation of  these SoCs, and the difference between the Alpha 9 Gen 2 and Alpha 7 Gen 2  with respect to LUT sizes is the same as between the Alpha 9 and Alpha 7 used  in 2018 TVs 
 
● What are the impact to Game Modes? 
 
New for 2019:   

○ The HDR Gaming Interest Group (​www.hgig.org​) has created guidelines for displays, consoles and games to improve HDR Game Rendering. Using the  HDR10 Tone Map parameters, it is possible to set the Game Mode HDR tone  curve to accurately track PQ and hard clip at measured panel peak luminance. This  will provide a best case implementation of the rendering guidelines of the HGIG.    

Unchanged for 2019: 
 
○ This functionality will allow a vast improvement in colour accuracy for the low latency Game picture modes. Previously, the Game modes did not have user  access to the detailed calibration controls that were available in the other modes  (e.g. Cinema mode, or HDR Cinema.) Now there is no calibration difference  between the low latency Game modes, and any other mode.  
 
○ This calibration feature was based on feedback from game developers, and end  users that made it clear that game video content should not be treated any  different than movie or TV content. Some of the AAA game titles have development costs eclipsing big name movies, and game developers have made it  clear that color accuracy is just as important to them as it is their movie  counterparts. They want their creative intent to be preserved as much as  Hollywood filmmakers do. 
 
● Will it be possible for 2018 TVs to be updated to support the new features launched  in 2019? 
 
○ Almost certainly no for consumers. Development work for these features started  on 2018 TVs, and some of our partners in content production have been using  engineering firmware for 2018 TVs, and we will continue to support the partners  that we worked with on this with their 2018 units, but it is not something that will  be back ported and supported for consumers with 2018 models. 
 
● When will these feature be added to products? 
 
Unchanged for 2019: 
 
○ These features are not vaporware or even really pre-production. The software in  our TVs to support these functions is already in the main development branch and  only bug fixes will take place between now and the launch of these models.  SpectraCal’s software likewise is at a point where only bug fixes will take place  between now and launch. 
 
● What other applications has the hardware level LUT access enabled besides  calibration?   

○ LG TVs are now being used for colour science research in multiple research  settings. Universities including RIT are conducting consumer studies with our  OLED TVs, and Hollywood consultant colour scientists including Gary Demos are  using our OLED TVs for developing new approaches to colour volume mapping  and EOTFs.   

○ Although the API for communicating with our TVs is not public, the API and  additional tools are available to partners that we have a relationship with to  enable access to additional features that CalMAN does not expose or make use of.  Please reach out to Neil Robinson if you would be interested in getting access to  this information