Why 'more or less stopped using ISO'?

Started Feb 19, 2014 | Questions thread
Iliah Borg Forum Pro • Posts: 25,440
Re: Maybe this will help.

crames wrote:

Iliah Borg wrote:

crames wrote:

Subjective absolute You do not know brightness, you can only say which one is brighter. Forget absolute.

Subjective absolute....Forget absolute. Hmmm?

Sorry to have corrected "the corrector."

Here's a quote from Fairchild's Color Appearance Models that might help those who find this to be confusing (not you, Iliah!)

After presenting definitions of Brightness and Lightness in the same terms as the CIE, he says,

"The definitions of brightness and lightness are straightforward and rather intuitive. The important distinction is that brightness refers to the absolute level of perception, while lightness can be thought of as relative brightness, normalized for changes in the illumination and viewing conditions.

"A classic example is to think about a piece of paper, such as this book page. If this page was viewed in a typical office environment, the paper would have some brightness and a fairly high lightness (perhaps it is the lightest stimulus in the field of vision and therefore white). If the book was viewed outside on a sunny summer day, there would be significantly more energy reflected from the page and the paper would appear brighter. However, the paper would still likely be the lightest stimulus in the field of vision and so would retain its high lightness, approximately the same lightness it exhibited in the office illumination. In other words, the paper still appears white, even though it is brighter outdoors..."

The problem is that everything about perception is subjective by definition. When somebody says this light bulb is bright he does not mean it is bright, he means either it is bright enough or it is brighter than another bulb. Also, when he says it is bright another person may consider it to be dim.

Perception does not operate in absolute terms. Even perception of distance - very few people can tell the distance to a boat on the still lake. Worse, without the knowledge of the size of boats it is usually impossible to tell which of two boats is closer. Very few people have perfect pitch, perfect colour discrimination, perfect ability to compare brightness.

Overloading physics with terms and definitions that are unnecessary helps only to create confusion and maintain consultant status.

When a branch of physics needs too many descriptive terms it is not yet developed to be considered as science.

If you look at different natural languages you may discover that brightness follow the pattern as being a comparative, very rarely found in constructs such as "brightness is".

Absolut is a rather good vodka from Sweden. But it is not the best one whatever they name it. And often forged.

"Absolute" in terms of perception of brightness means that the perception is proportional to the luminance on an open-ended scale.

Again, absolute and subjective are incompatible. Second, in his classic example Mark substituted brightness with a comparative.

I do not see you using the term brightness alone here, you rather used "perception of brightness". Sensors do not perceive. All of this is not adequate if we are talking of the measurements which is how the sensors function.

More luminance leads to a perception of more brightness.

Adaptation does not happen here? Ummmm.

It doesn't mean that someone can look at a patch of color and tell you what its exact, absolute luminance value is (although someone might have that ability, like perfect pitch.)

Perfect pitch is quite often not that perfect, it usually is rounding to 1/4 or 1/8 of optimized fixed perceptional scale, as a result of trained memory. Changing the scale throughs it off.

Perception is fundamentally a comparison, such is the nature of perception. No need to attempt to make it absolute, it leads nowhere.

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