Steve Shaw

Pixel sniffing will not really prove anything, and nore will a grey scale image, as a viable film emulation LUT will have cross-colour contamination, varianle grey scale colour temp,, and other artefacts, as that is what film has by default... It is a very, very non-linear colour medium!

See: https://www.lightillusion.com/free_look_luts.html

But, as the page shows, there are a lot of bad LUTs out there.

Steve

It varies batch to batch, and lab to lab, and day to day...

Welcome to the world of film.

We are accurate to the stock provided to us, and the processing it has undergone.

When building film emulation LUTs for real film productions we generate new emulation LUTs when any one of the above changes...

Steve

All film colourimetry data is measured from the provided film stocks using a highly accurate hybrid spectrophotometer & densitometer combined with an extremely stable and fully automated stepper motor controlled film transport system.

it is very, very accurate+

Mark, are you using an external LUT box to calibrate the Sony, or just using the in-built (and very limited) grey scale calibration Sony provide?

As Abby hints at, we are not impressed with Sony's lack of professional in-built calibration capabilities in any of their displays. In today's world there is no excuse for not providing full user calibration via external calibration systems to upload accurate 3D LUTs.

Steve

16% to 20% Discounts on Jeti, Klein and X-Rite probes, as well as Murideo SIX-G and SIX-A generator and analyser, as well as up to 50% off LightSpace CMS...

Steve

https://www.lightillusion.com/forums/index.php?action=vthread&forum=13&topic=446

In 2 days the specials will be posted.

Subscribe to the forum thread to be messaged when the news goes live.

Steve

Looks like the sRGB has been incorrectly based on the encoding Gamma formula.

It should be a pure 2.2 power law gamma.

The encoding gamma fore Rec709 is similar...

Steve

Well, that's wrong...

And why is there an 'S' profile to the curves? sRGB and Rec709 are pure power law. (but as I don't know how the graphs were created I'm probably missing something).

Steve

Just so you know the ONLY difference between Rec709 and sRGB is Rec709 is (nominally) gamma 2.4, and sRGB Gammas 2.2.

There is no other difference.

Steve

I can't trust any display that can't be user calibrated - ever. Having to add a LUT box to Sony display to calibrate them (regardless whether that is because of poor factory calibration, or die to display drift, as they ALL suffer) is just not acceptable in any professional display.

We have not tested the v2 Sony X300, but the v1 versions we tested we not gamut accurate.

But, I trust Juan's ability to test and verify any display - he really does know what he's doing!

Steve.

Actually, sRGB is 2.2, and Rec709 2.4 gamma. The concept of 2.199 comes from trying to 'average' the 'Encoding gamma' of sRGB, which has nothing to do with calibration or grading/image manipulation.

BT1886 is an attempt to modify the 'shadows' based on the black point of a display, and is for calibration only - byt as issues as it lifts the shadows on a display that has lifted blacks... that ca be an issue when grading.

A display with a zero black point will cause BT1886 to define a pure power law 2.4 gamma.

Steve

BT1886 is just a display calibration gamma, and should not be used for any 'conversions'. You should only use Power Law gamma for conversions.

Also, Rec709 is 2.4 gamma, and sRGB 2.2.

A display with a zero black will calibrate using BT1886 to a 2.4 power law. With a raised black you will get lifted shadows. This is one of the issues with BT1886, as the lifted shadows will cause you, the colourist. to over compensate by grading the shadows darker. The end result will be potentially crushed shadows/blacks when viewed on a display that is not calibrated to Bt1886, but has a lifted black point, as many home TV have...

Steve

The default Sony white point (Judd/Voss) offset has been changed a number of times, and still doesn't work... It is why we worked with FSI (who use the Sony OLED glass) to develop the 'Perceptual Match' approach to overcoming Metameric issues:

http://www.lightillusion.com/perceptual_colour_match.html

And although the LG OLEDs are WRGB, they still suffer Metameric Failure, and will need a different Perceptual match white point.

Separately, Sony do not allow for accurate user calibration, providing for grey scale calibration only. And as the Sony gamut calibration is not accurate from the factory, ignoring any drift through ageing of the display, that is not good for a professional display.

Steve

Many (most?) of the film emulation LUTs available from the various suppliers out there have been generated using data provided by Light Illusion, as well as through the use of LightSpace CMS and/or matchLight IMS.

See: http://www.lightillusion.com/lightspace.html

and: http://www.lightillusion.com/matchlight_ims.html

There are also some free film emulation LUTs that can be downloaded, and information how the LUTs were generated here: http://www.lightillusion.com/free_look_luts.html

There is also info on what LUTs really are here: http://www.lightillusion.com/luts.html

And more importantly, a lot of info on using LUTs for calibration, which is their main use, and other aspects of LUT use and colour management workflows, etc., here: http://www.lightillusion.com/tech_info.html

And you can always ask me questions directly.

Steve