Re: referenceWhiteluminance added to the strawman

Looks good

 

Comments on color conversion:

 
Typos?
CURRENT:

function simpleTransform(value, systemGamma) {

  if (value < 1.0) {

    return -1.0 * Math.pow(-1.0 * value, systemGamma);

  } else {

    return Math.pow(value, systemGamma);

  } 

}

 

function simpleInverseTransform(value, systemGamma) {

  if (value < 1.0) {

    return -1.0 * Math.pow(-1.0 * value, 1.0 / systemGamma);

  } else {

    return Math.pow(value, 1.0 / systemGamma);

  }

}

 

I believe the if statements should be if (value < 0.0)

 
I belive pq to srgb needs a similar code snippet to map to sRGB gamut:
 

const r3 = simpleInverseTransform(r2, systemGamma);

  const g3 = simpleInverseTransform(g2, systemGamma);

  const b3 = simpleInverseTransform(b2, systemGamma);

  const [r4, g4, b4] = limitTosRGBGamut(r3, g3, b3);

 
Why is PQ to srgb using gamma 2.4 while HLG uses 2.2? 2.2 is usually the better fit for sRGB. But maybe you want 709 brightness levels?
 

Best,

 

Lars

 

-----Original Message-----

From: Pierre Lemieux <pal@sandflow.com <mailto:pal@sandflow.com>>

Date: Monday, October 16, 2023 at 7:10 PM

To: "public-colorweb@w3.org <mailto:public-colorweb@w3.org>" <public-colorweb@w3.org <mailto:public-colorweb@w3.org>>

Subject: referenceWhiteluminance added to the strawman

Resent-From: <public-colorweb@w3.org <mailto:public-colorweb@w3.org>>

Resent-Date: Monday, October 16, 2023 at 7:10 PM

 

 

Good morning/evening,

 

 

Per our last discussion, please find at [1] a revised strawman that

adds a referenceWhiteluminance parameter to the advanced information

available from the output device.

 

 

referenceWhiteluminance specifies the luminance of reference white as

reproduced by the screen of the output device, and reflects the

viewing environment. It effectively describes the headroom available

for

HDR imagery.

 

 

Best,

 

 

-- Pierre

 

 

[1] https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fw3c%2FColorWeb-CG%2Fblob%2Ffeature%2Fadd-mastering-display-info%2Fhdr_html_canvas_element.md%23add-display-color-volume-information-to-screen-interface-of-the-css-object-model&data=05%7C01%7Cborg%40adobe.com%7C1784d5a36414408464bf08dbcecf6f8f%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C638331162552543282%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=9ffN3L9lyyYWFhCIANLAQbEErg%2BAjte7GYoWHp73sgE%3D&reserved=0 <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fw3c%2FColorWeb-CG%2Fblob%2Ffeature%2Fadd-mastering-display-info%2Fhdr_html_canvas_element.md%23add-display-color-volume-information-to-screen-interface-of-the-css-object-model&amp;data=05%7C01%7Cborg%40adobe.com%7C1784d5a36414408464bf08dbcecf6f8f%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C638331162552543282%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=9ffN3L9lyyYWFhCIANLAQbEErg%2BAjte7GYoWHp73sgE%3D&amp;reserved=0>