{"id":237,"date":"2014-11-12T15:53:39","date_gmt":"2014-11-12T20:53:39","guid":{"rendered":"https:\/\/designinglight.com\/?p=237"},"modified":"2014-11-12T15:55:50","modified_gmt":"2014-11-12T20:55:50","slug":"light-and-color-perception","status":"publish","type":"post","link":"https:\/\/designinglight.com\/?p=237","title":{"rendered":"Light and Color Perception"},"content":{"rendered":"

NPR\u2019s All Things Considered<\/em> had a brief piece<\/a> about light and color on Monday. The main thrust of the story was that color is not inherent in an object, but is perceived and interpreted by our brain, but there\u2019s much more to revealing and perceiving the color of objects. Here\u2019s a quick overview.<\/p>\n

To begin, all objects have light reflecting properties. Objects that we identify as red reflect most of the red light that falls on them and absorb the other colors. Likewise for objects that appear to be green, blue, etc. Objects that appear to be white reflect the colors of light more or less equally, while objects that appear to be black absorb most of the light that falls on them. Objects only reflect light, they don\u2019t create it, so if we use blue light to illuminate an object that reflects red light we find that no light is reflected and the object appears to be black.<\/p>\n

As I explain in Chapter 8, we change the balance of the colors in white light every time we change the light source. Even with a single light technology, such as fluorescent, we change the balance of colors when we change from cool white to warm white. The color content of a light source can be measured (it\u2019s called the spectral power distribution or SPD) and graphed as shown below.<\/p>\n

\"SPD<\/a>
SPD of Daylight<\/figcaption><\/figure>\n

 <\/p>\n

\"SPD<\/a>
SPD of a Cool White Fluorescent<\/figcaption><\/figure>\n

When we change the SPD we change the colors of light that are available for reflection by objects, which means that we also change the balance of light that is reflected and thus the color information that our eyes receive. The result is that changing the light may change the color appearance, or the apparent color, of an object. Many of us have had the experience of buying clothing or paint that was one color in the store and another color at home. Here we see this phenomenon with a color\/materials board illuminated by several light sources. \u00a0How well a light source enables us to perceive colors is called color rendering.<\/p>\n

\"Illuminated<\/a>
Illuminated with Incandescent Lamp<\/figcaption><\/figure>\n
\"Illuminated<\/a>
Illuminated with Warm White Fluorescent Lamp<\/figcaption><\/figure>\n
\"Illuminated<\/a>
Illuminated with Cool White Fluorescent Lamp<\/figcaption><\/figure>\n

Color and brightness perception are both relative not absolute. A candle in an otherwise dark room may seem too bright to look at directly, while its brightness on a sunny day seems insignificant. In addition to the effect of SPD on our color perception, colors are perceived in relation to one another, especially between foreground and background as shown below.<\/p>\n

\"The<\/a>
The color of the dots is the same in both figures. The strong background colors affect perception of foreground colors.<\/figcaption><\/figure>\n

If I can demonstrate shifting our color perception why don\u2019t we experience it in everyday life? Why are my blue jeans blue and my red car red in nearly every lighting situation? The answer is color constancy or chromatic adaptation. It does us no good to spend time and energy struggling to figure out colors. We want to be able to tell if a piece of fruit is ripe regardless of the lighting conditions. Color constancy is our brain\u2019s use of information gathered from the entire visual field to understand the lighting conditions and calibrate our color perception so that color shifts are minimized.<\/p>\n","protected":false},"excerpt":{"rendered":"

NPR\u2019s All Things Considered had a brief piece about light and color on Monday. The main thrust of the story was that color is not inherent in an object, but is perceived and interpreted by our brain, but there\u2019s much more to revealing and perceiving the color of objects. Here\u2019s a quick overview. To begin, … Continue reading Light and Color Perception<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[12,17,15],"tags":[61,27],"class_list":["post-237","post","type-post","status-publish","format-standard","hentry","category-color","category-light","category-vision","tag-color-perception","tag-color-rendering"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p4gZSw-3P","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":3148,"url":"https:\/\/designinglight.com\/?p=3148","url_meta":{"origin":237,"position":0},"title":"AI and the Internet Need to Learn Color Rendering","author":"Jason Livingston","date":"March 28, 2023","format":false,"excerpt":"Recently a colleague of mine from the IES Color Committee asked of one of the new AIs \"Tell me about color rendering.\" \u00a0If we assume that the answer was formulated based on information about color rendering that is available on the internet we have a problem because the answer the\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":92,"url":"https:\/\/designinglight.com\/?p=92","url_meta":{"origin":237,"position":1},"title":"The Best Light?","author":"Jason Livingston","date":"January 31, 2014","format":false,"excerpt":"In class yesterday one of my students, thinking about a project she had recently completed, asked, \"What's the best light for a hair salon?\" \u00a0I'm certain she was hoping I would tell her exactly what lamp technology and\/or lamp style to use. \u00a0Of course, it's not that simple. So the\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1977,"url":"https:\/\/designinglight.com\/?p=1977","url_meta":{"origin":237,"position":2},"title":"The Strength of TM-30","author":"Jason Livingston","date":"September 28, 2021","format":false,"excerpt":"The strength of using TM-30 to evaluate light source color rendering.","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2021\/09\/Screen-Shot-2021-09-28-at-7.51.45-AM.png?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2021\/09\/Screen-Shot-2021-09-28-at-7.51.45-AM.png?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2021\/09\/Screen-Shot-2021-09-28-at-7.51.45-AM.png?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2021\/09\/Screen-Shot-2021-09-28-at-7.51.45-AM.png?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2021\/09\/Screen-Shot-2021-09-28-at-7.51.45-AM.png?resize=1050%2C600&ssl=1 3x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2021\/09\/Screen-Shot-2021-09-28-at-7.51.45-AM.png?resize=1400%2C800&ssl=1 4x"},"classes":[]},{"id":617,"url":"https:\/\/designinglight.com\/?p=617","url_meta":{"origin":237,"position":3},"title":"IES Symposium Summary","author":"Jason Livingston","date":"April 6, 2016","format":false,"excerpt":"If you missed IES Research Symposium III Light + Color you missed an exciting (for color geeks) few days. It would take too long to relate everything that was discussed, but here are some key highlights. TM-30-15 is seeing broader acceptance throughout the industry. In an exciting development, it seems\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":386,"url":"https:\/\/designinglight.com\/?p=386","url_meta":{"origin":237,"position":4},"title":"A New Color Rendering Metric","author":"Jason Livingston","date":"May 11, 2015","format":false,"excerpt":"At last week\u2019s Lightfair one of the presentations was Quantifying Color Rendition: A Path Forward. The presentation was the first public look at the (not yet approved) IES Method of quantifying color rendering. What is this new (not yet approved) IES Method? Let\u2019s start with a quick review of the\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"CRI Test Color Sample SPDs","src":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2015\/05\/CIE_CRI_TCS_SPDs.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2015\/05\/CIE_CRI_TCS_SPDs.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2015\/05\/CIE_CRI_TCS_SPDs.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":780,"url":"https:\/\/designinglight.com\/?p=780","url_meta":{"origin":237,"position":5},"title":"The Advantages of TM-30","author":"Jason Livingston","date":"October 30, 2017","format":false,"excerpt":"In this series of posts about IES TM-30-15 I've discussed the problems with CRI and the resistance to adopting TM-30. \u00a0In this post I'll discuss the advantages of TM-30 over CRI, and what TM-30 is and isn't. Color Samples Like CRI, TM-30 compares color samples rendered by a given test\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2017\/10\/TM-30-Bins.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2017\/10\/TM-30-Bins.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2017\/10\/TM-30-Bins.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts\/237","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=237"}],"version-history":[{"count":4,"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts\/237\/revisions"}],"predecessor-version":[{"id":248,"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts\/237\/revisions\/248"}],"wp:attachment":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=237"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=237"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=237"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}