{"id":2579,"date":"2010-10-15T22:46:16","date_gmt":"2010-10-15T12:46:16","guid":{"rendered":"http:\/\/hifi-writer.com\/wpblog\/?p=2579"},"modified":"2010-10-15T22:46:16","modified_gmt":"2010-10-15T12:46:16","slug":"subtracting-colours","status":"publish","type":"post","link":"https:\/\/hifi-writer.com\/wpblog\/?p=2579","title":{"rendered":"Subtracting colours"},"content":{"rendered":"<p>Yesterday I got my hands on a sample of a projector that will soon be released. It worked beautifully yesterday but, as is often the case with samples, it developed a problem which appeared in fits and starts today, and finally locked in, apparently permanently.<\/p>\n<p>I&#8217;ve recreated the visual appearance of the problem using Photoshop on a SD digital TV frame I happened to have on my computer. Here&#8217;s what I saw:<\/p>\n<p><a href=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusblue.jpg\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-2581\" title=\"minusblue\" src=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusblue.jpg\" alt=\"\" width=\"500\" height=\"281\" srcset=\"https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusblue.jpg 500w, https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusblue-300x168.jpg 300w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n<p>Clearly something is amiss, but what is it? Initially I thought that the projector and my home theatre receiver were having a disagreement about the colour space. HDMI can carry the video in the form of RGB or component video. Sometimes a display incorrectly interprets one as the other, producing very interesting colour effects.<\/p>\n<p>But I noticed that what was supposed to be the white text of the projector&#8217;s own menus was also appearing as bright yellow. The penny dropped: white minus blue equals yellow. This was a 3 panel projector, and produced the image using the red, green, blue colour scheme. Disable the blue and all that&#8217;s left is red and green, which added together look yellow.<\/p>\n<p>I generated the frame above by killing all the blue in the following frame:<\/p>\n<p><a href=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/allcolour.jpg\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-2580\" title=\"allcolour\" src=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/allcolour.jpg\" alt=\"\" width=\"500\" height=\"281\" srcset=\"https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/allcolour.jpg 500w, https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/allcolour-300x168.jpg 300w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n<p>Interestingly, it seems that blue is the most\u00a0dispensable\u00a0of the three colours. The top frame is almost watchable. Compare that to the following two, first with the green extracted:<\/p>\n<p><a href=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusgreen.jpg\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-2582\" title=\"minusgreen\" src=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusgreen.jpg\" alt=\"\" width=\"500\" height=\"281\" srcset=\"https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusgreen.jpg 500w, https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusgreen-300x168.jpg 300w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n<p>and then with the red removed:<\/p>\n<p><a href=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusred.jpg\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-2583\" title=\"minusred\" src=\"http:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusred.jpg\" alt=\"\" width=\"500\" height=\"281\" srcset=\"https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusred.jpg 500w, https:\/\/hifi-writer.com\/wpblog\/wp-content\/uploads\/2010\/10\/minusred-300x168.jpg 300w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Yesterday I got my hands on a sample of a projector that will soon be released. It worked beautifully yesterday but, as is often the case with samples, it developed a problem which appeared in fits and starts today, and &hellip; <a href=\"https:\/\/hifi-writer.com\/wpblog\/?p=2579\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[12,24,5],"tags":[],"_links":{"self":[{"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=\/wp\/v2\/posts\/2579"}],"collection":[{"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2579"}],"version-history":[{"count":4,"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=\/wp\/v2\/posts\/2579\/revisions"}],"predecessor-version":[{"id":2587,"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=\/wp\/v2\/posts\/2579\/revisions\/2587"}],"wp:attachment":[{"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2579"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2579"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hifi-writer.com\/wpblog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2579"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}