Editing Color vision (section)

== Subjectivity of color perception <span class="anchor" id="Subjectivity"></span>==
{{further|Color appearance}}
{{See also|Linguistic relativity and the color naming debate}}

Color is a feature of visual perception by an observer.  There is a complex relationship between the wavelengths of light in the visual spectrum and human experiences of color.  Although most people are assumed to have the same mapping, the philosopher [[John Locke]] recognized that alternatives are possible, and described one such hypothetical case with the "[[inverted spectrum]]" thought experiment.  For example, someone with an inverted spectrum might experience green while seeing 'red' (700&nbsp;nm) light, and experience red while seeing 'green' (530&nbsp;nm) light. This inversion has never been demonstrated in experiment, though.

[[Synesthesia]] (or [[ideasthesia]]) provides some atypical but illuminating examples of subjective color experience triggered by input that is not even light, such as sounds or shapes.  The possibility of a clean dissociation between color experience from properties of the world reveals that color is a subjective psychological phenomenon.

The [[Himba people]] have been found to categorize colors differently from most Westerners and are able to easily distinguish close shades of green, barely discernible for most people.<ref>{{cite book | vauthors = Roberson D, Davidoff J, Davies IR, Shapiro LR | chapter = Colour categories and category acquisition in Himba and English | chapter-url = https://eclass.uoa.gr/modules/document/file.php/ECD246/Διάφορα%20κείμενα%20και%20για%20εργασίες/ProgressInColour.pdf | veditors = Pitchford N, Biggam CP | title = Progress in Colour Studies | volume = II. Psychological aspects | date = November 2006 | pages = 159–72 | isbn = 978-90-272-9302-2 | publisher = John Benjamins Publishing }}</ref> The Himba have created a very different color scheme which divides the spectrum to dark shades (''zuzu'' in Himba), very light (''vapa''),  vivid blue and green (''buru'') and dry colors as an adaptation to their specific way of life.

The perception of color depends heavily on the context in which the perceived object is presented.<ref>{{Cite book |last=Nänni |first=Jürg |title=Visual perception - an interactive journey of discovery through our visual system |publisher=Niggli AG |year=2008 |isbn=978-3-7212-0618-0 |location=Sulgen Zurich, Switzerland |language=German, English}}</ref>

Psychophysical experiments have shown that color is perceived before the orientation of lines and directional motion by as much as 40ms and 80 ms respectively, thus leading to a [[perceptual asynchrony]] that is demonstrable with brief presentation times.

=== Chromatic adaptation ===
{{Main|Chromatic adaptation}}

In color vision, chromatic adaptation refers to [[color constancy]]; the ability of the visual system to preserve the appearance of an object under a wide range of light sources.<ref name="Fairchild_2005">{{cite book| vauthors = Fairchild MD |title=Color Appearance Models|publisher=Wiley|year=2005|isbn=978-0-470-01216-1|page=146|chapter=8. Chromatic Adaptation|chapter-url=https://books.google.com/books?id=8_TxzK2B-5MC&q=%22chromatic+adaptation%22&pg=PA146}}</ref> For example, a white page under blue, pink, or purple light will reflect mostly blue, pink, or purple light to the eye, respectively; the brain, however, compensates for the effect of lighting (based on the color shift of surrounding objects) and is more likely to interpret the page as white under all three conditions, a phenomenon known as [[color constancy]].

In color science, chromatic adaptation is the estimation of the representation of an object under a different light source from the one in which it was recorded. A common application is to find a ''chromatic adaptation transform'' (CAT) that will make the recording of a neutral object appear neutral ([[color balance]]), while keeping other colors also looking realistic.<ref>{{cite web | vauthors = Süsstrunk S | url = http://ivrgwww.epfl.ch/research/past_topics/chromatic_adaptation.html | title = Chromatic Adaptation | archive-url = https://web.archive.org/web/20110818184220/http://ivrgwww.epfl.ch/research/past_topics/chromatic_adaptation.html| archive-date = 2011-08-18 | work = The Image and Visual Representation Lab (IVRL) }}</ref> For example, chromatic adaptation transforms are used when converting images between [[ICC profile]]s with different [[white point]]s. [[Adobe Photoshop]], for example, uses the Bradford CAT.<ref>{{cite web | vauthors = Lindbloom B | url = http://www.brucelindbloom.com/Eqn_ChromAdapt.html | title = Chromatic Adaptation | archive-url = https://web.archive.org/web/20110926223613/http://www.brucelindbloom.com/Eqn_ChromAdapt.html| archive-date=2011-09-26 | work = Lindbloom.com }}</ref>