{"id":110,"date":"2006-12-29T07:00:57","date_gmt":"2006-12-29T12:00:57","guid":{"rendered":"https:\/\/blogs.mathworks.com\/steve\/?p=110"},"modified":"2006-12-22T15:17:53","modified_gmt":"2006-12-22T20:17:53","slug":"b-profile-connection-space","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/steve\/2006\/12\/29\/b-profile-connection-space\/","title":{"rendered":"B = &#8220;Profile Connection Space&#8221;"},"content":{"rendered":"<p>A couple of weeks ago I asked if anyone could guess what this \"equation\" means on my office whiteboard:\r\n\r\n<p>\r\n<img decoding=\"async\" src=\"https:\/\/blogs.mathworks.com\/images\/steve\/107\/IMG_1253_small.jpg\" alt=\"B=PCS\" \/>\r\n\r\n<p>\r\nIt's related to the color management approach standardized by the <a href=\"http:\/\/www.color.org\">International Color Consortium (ICC)<\/a>. In this approach, each input device (a camera, for example) or output device (such as a printer) has an associated <em>color profile<\/em>. The color profile contains a numeric \"recipe\" (multiple recipes, actually) for converting colors between the device's own color space and one of two standard colorimetric spaces: XYZ and L*a*b*. The standard space is called the <em>profile connection space<\/em>, or PCS.\r\n\r\n<p>\r\nThe idea is to allow color management systems to transform colors appropriately as they move from an input device to a computer display, and then to an output device. All color space transformations in the pipeline work by \"connecting\" through one of the two standard profile connection spaces.\r\n\r\n<p>\r\nICC profiles contain transformation recipes that go both ways: from the device to the PCS, and from the PCS to the device. The lookup tables, curves, and matrices that make up the recipes are stored in <em>tags<\/em> in the profile. These tags have names like <tt>AToB<\/tt> and <tt>BToA<\/tt>.\r\n\r\n<p>\r\nWhich finally brings us to the answer to my whiteboard mystery: I have a lousy memory! I could never remember whether \"A\" referred to the device space, or to the profile connection space. I was always having to look it up in the spec.  One day I got tired of this and wrote \"B = PCS\" on my whiteboard.\r\n\r\n<p>\r\nMaybe I'll leave it there forever.\r\n\r\n<p>\r\n<strong>Happy New Year, everyone!<\/strong>","protected":false},"excerpt":{"rendered":"<p>A couple of weeks ago I asked if anyone could guess what this \"equation\" means on my office whiteboard:\r\n\r\n\r\n\r\n\r\n\r\nIt's related to the color management approach standardized by the International... <a class=\"read-more\" href=\"https:\/\/blogs.mathworks.com\/steve\/2006\/12\/29\/b-profile-connection-space\/\">read more >><\/a><\/p>","protected":false},"author":42,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/posts\/110"}],"collection":[{"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/users\/42"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/comments?post=110"}],"version-history":[{"count":0,"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/posts\/110\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/media?parent=110"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/categories?post=110"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.mathworks.com\/steve\/wp-json\/wp\/v2\/tags?post=110"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}