Talk:Helmholtz–Kohlrausch effect

Confused discussion of stage lighting

The article:

On stage, lighting users have the ability to make the colored lights appear much brighter than the white light by adding gels. This occurs even though gels can only absorb some of the light.

Two problems here: (1) the gels (not an actual gel, they're sheets or plaques of translucent plastic or similar material essentially identical to ones used every day in elementary school science and art classes) are what color the light in the first place, not something that augments already-colored light to make it brighter. (2) The apparent paradox isn't that the effect is present despite the gel not absorbing all of the light, it's the exact opposite: the colored light appears brighter in spite of the fact that the gels absorb part of the light, resulting in less light, in absolute terms, reaching the stage. If the gels were able to absorb all of the light, then they'd be opaque and no light at all would reach the stage. --2601:140:8000:A739:D83E:4EF9:3E06:818F (talk) 17:11, 25 May 2019 (UTC)[reply]

Illustration

I converted the top image to grayscale and I did NOT have the image on the bottom. --Stankot (talk) 17:07, 13 March 2016 (UTC)[reply]
Forget the grammar, you know what I mean:) --Stankot (talk) 19:42, 14 March 2016 (UTC)[reply]

I also converted thee image to grayscale in three different ways in Photoshop and did not get a flat grey rectangle either. I have tried creating a correct image myself, but found that the brightness and lightness values used in my software's color models are not necessarily linear representations of luminosity, so I wouldn't know how to do it. --LongWindingRoad (talk) 22:10, 24 March 2017 (UTC)[reply]

Using my knowledge of colorimetry, I have made an alternate versions of this graph, for which I hope the methodology will be clearer. This version is produced such that the CIE 1931 XYZ channel's Y (luminance as defined by the CIE °2 standard observer) is identical across the image. This can be confirmed by using e.g. convert Helmholtz-Kohlrausch_effect-xyz.svg -colorspace XYZ -channel 2 -separate gray.png, and I have also independently verified it using a colorimeter and calibrated IPS display. This choice of normalization (CIE Y) is the one that most directly illustrates the named effect, which states that different chromaticities appear to “stand out” more even at the same Luminance. I don't know my way around wikipedia policy well enough to update the existing image-place, so I'll throw it out here for now. 109.193.81.112 (talk) 23:32, 23 June 2017 (UTC)[reply]

Please note that we will never get a perfect result when converting to grayscale, because colors are encoded with 8 bpc. So there will always be tiny variations between patches. However this work was not accurate at all. I fixed it and now Y value (luminance) is more constant. Bhutajata (talk) 14:22, 2 October 2017 (UTC)[reply]

"Spectral lights"?

In the sentence:

It appears in both self-luminous and surface colors, although it is most pronounced in spectral lights.

...what does "spectral lights" mean? FrankSier (talk) 08:49, 21 June 2020 (UTC)[reply]

This page is a hoax.

This page is a clear, blatant, and obvious hoax. This is not how color works. All colors are equal. Color as a concept is consistent. Humans do not perceive different colors differently; all claims otherwise are cultural propaganda. This philosophical propaganda must be deleted for the sake of humanity.

Regards,

—2600:1700:E4C0:9EA0:B110:7F80:D99A:A67D (talk) 05:07, 12 February 2022 (UTC)[reply]

This effect is documented in numerous scientific publications, and while it's very susceptible to different viewing conditions and media, it's certainly real. I can only hope, that this is some sort of terrible parody, "for the sake of humanity"... ThomasBorchard (talk) 07:59, 9 August 2023 (UTC)[reply]

It is not a parody. 2600:1700:E4C0:9EA0:81E:C858:7C7D:D0D8 (talk) 21:28, 26 April 2024 (UTC)[reply]