17522 2012-06-16 23:25:29 +0000 pixelDepth and colorDepth do not mean the same thing. 2013-08-08 13:28:44 +0000 1 1 1 Unclassified CSS CSSOM View unspecified All All RESOLVED FIXED P2 major --- 1 neils.christoffersen zcorpan glenn zcorpan public-css-bugzilla oldest_to_newest 69159 0 neils.christoffersen 2012-06-16 23:25:29 +0000 The CSSOM View spec section 4.2 defines two properties on the Screen interface: pixelDepth and colorDepth. The spec is unclear/wrong on two counts: 1. pixelDepth and colorDepth are defined together, implying that they should always be the same. If they are always identical, then there is no point in having two properties. 2. Pixel depth and color depth do not always mean the same thing, depending on the display device. 71811 1 glenn 2012-08-03 05:55:22 +0000 reassign to myself; apparently i am not the default assignee for this component 87652 2 zcorpan 2013-05-14 14:52:19 +0000 How are they different? 89459 3 glenn 2013-06-18 09:10:44 +0000 (In reply to comment #2) > How are they different? colorDepth is (or is often interpreted as) bits per component, also called bits per sample; while pixelDepth often refers to the combination of bits for a pixel contributed by all applicable samples; so, e.g., RGBA4444 is 4 bits per sample, or colorDepth 4 but pixelDepth 16; see https://en.wikipedia.org/wiki/Color_depth for more discussion at present the definitions of both colorDepth and pixelDepth in Section 5.2 are wrong 89466 4 zcorpan 2013-06-18 09:57:23 +0000 Ah. Yes, they are different to the industry terms 'color depth' and 'pixel depth'. However, the current definition is interoperably implemented in Presto/Blink/WebKit/Gecko/IE, as far as I can tell. This is a case where the implementations predated the spec, I believe. 89468 5 glenn 2013-06-18 09:59:21 +0000 The implementations are broken. We fix broken implementations all the time. Do not close this bug again without addressing it substantively. 89470 6 zcorpan 2013-06-18 10:02:42 +0000 *** Bug 14071 has been marked as a duplicate of this bug. *** 89474 7 zcorpan 2013-06-18 12:59:58 +0000 In http://webdevdata.org/ data-dec2012 I see 3269 matches of "\.(color|pixel)Depth". Looking through the matches, it seems like basically all of them are for the purpose of tracking. Here's an example: document.write("<img src='http://counter.yadro.ru/hit;prian?r"+ escape(document.referrer)+((typeof(screen)=="undefined")?"": ";s"+screen.width+"*"+screen.height+"*"+(screen.colorDepth? screen.colorDepth:screen.pixelDepth))+";u"+escape(document.URL)+ ";"+Math.random()+ "' width=1 height=1 alt=''>") 89573 8 zcorpan 2013-06-19 08:54:33 +0000 I made them always return 24. https://dvcs.w3.org/hg/csswg/rev/e87354ee3440