130582 2014-03-21 05:27:49 -0700 [CSS Blending] Wrong color result for basic blend modes 2014-11-12 13:06:06 -0800 1 1 1 Unclassified WebKit CSS 528+ (Nightly build) Unspecified Unspecified RESOLVED WORKSFORME InRadar P2 Normal --- 95614 131377 1 rosca webkit-unassigned ap mitica simon.fraser webkit-bug-importer WebkitBugTracker oldest_to_newest 993026 0 227417 rosca 2014-03-21 05:27:49 -0700 Created attachment 227417 Sample for 'difference' mode results According to the spec[1], the 'difference' blend mode should be computed using this formula: B(Cb, Cs) = | Cb - Cs |. For example: Fuchsia difference Aqua = Yellow The result in webkit is different than Yellow. On retina display it's a pale yellow rgb(204, 214, 0), but on non-retina displays, the result is a pale green rgb(0, 190, 0). The behaviour is the same for both accelerated and non-accelerated blending. I did not test for other blend modes than difference (TBD). [1] http://dev.w3.org/fxtf/compositing-1/#blendingdifference 993028 1 mitica 2014-03-21 05:35:03 -0700 (In reply to comment #0) > Created an attachment (id=227417) [details] > Sample for 'difference' mode results > > According to the spec[1], the 'difference' blend mode should be computed using this formula: B(Cb, Cs) = | Cb - Cs |. > For example: Fuchsia difference Aqua = Yellow > > The result in webkit is different than Yellow. On retina display it's a pale yellow rgb(204, 214, 0), but on non-retina displays, the result is a pale green rgb(0, 190, 0). > > The behaviour is the same for both accelerated and non-accelerated blending. I did not test for other blend modes than difference (TBD). > > [1] http://dev.w3.org/fxtf/compositing-1/#blendingdifference There are also problems with other blend modes. The biggest differences are with soft-light. In fact, when validating canvas blend modes, the tests submitted https://bugs.webkit.org/show_bug.cgi?id=119082 entirely skip soft-light since the differences between the formula and the result are consistent. Imho, this is rather a CG/CA bug. 1000999 2 webkit-bug-importer 2014-04-15 15:23:54 -0700 <rdar://problem/16626421> 1048230 3 ap 2014-11-12 13:06:06 -0800 This doesn't appear to be failing on bots any more, will remove the expectation. 227417 2014-03-21 05:27:49 -0700 2014-03-21 05:27:49 -0700 Sample for 'difference' mode results mix-blend-mode-bad-color.html text/html 2345 rosca PCFET0NUWVBFIGh0bWw+CjxzdHlsZSB0eXBlPSJ0ZXh0L2NzcyI+CiAgICAucGFyZW50IHsKICAg ICAgICB3aWR0aDogMTQwcHg7CiAgICAgICAgaGVpZ2h0OiAxNDBweDsKICAgICAgICBpc29sYXRp b246aXNvbGF0ZTsKICAgICAgICAtd2Via2l0LWlzb2xhdGlvbjppc29sYXRlOwogICAgfQogICAg LmJsZW5kZWQgewogICAgICAgIHdpZHRoOiAxNDBweDsKICAgICAgICBoZWlnaHQ6IDE0MHB4Owog ICAgICAgIC13ZWJraXQtbWl4LWJsZW5kLW1vZGU6IGRpZmZlcmVuY2U7CiAgICAgICAgbWl4LWJs ZW5kLW1vZGU6IGRpZmZlcmVuY2U7CiAgICAgICAgb3BhY2l0eTogMTsKICAgIH0KICAgIC5yb3cg PiBkaXYgewogICAgICAgIGZsb2F0OiBsZWZ0OwogICAgICAgIG1hcmdpbjogNXB4OwogICAgfQog ICAgLnJvdyB7CiAgICAgICAgZmxvYXQ6IGxlZnQ7CiAgICB9CiAgICAuYWNjZWxlcmF0ZWQgewog ICAgICAgIC13ZWJraXQtdHJhbnNmb3JtOiB0cmFuc2xhdGVaKDBweCk7CiAgICB9CiAgICBib2R5 IHsKICAgICAgICB3aWR0aDogNTAwcHg7CiAgICB9Cjwvc3R5bGU+Cjxib2R5PgogICAgPGRpdiBj bGFzcz0icm93Ij4KICAgICAgICA8cD55ZWxsb3cgKDI1NSwyNTUsMCkgPSAoMjU1LDAsMjU1KSBk aWZmZXJlbmNlICgwLDI1NSwyNTUpPC9wPgogICAgICAgIDxkaXYgY2xhc3M9InBhcmVudCIgc3R5 bGU9ImJhY2tncm91bmQ6IHJnYigwLDI1NSwyNTUpIj4KICAgICAgICAgICAgPGRpdiBjbGFzcz0i YmxlbmRlZCIgc3R5bGU9ImJhY2tncm91bmQ6IHJnYigyNTUsMCwyNTUpIj5Ob24tYWNjZWxlcmF0 ZWQgYmxlbmRpbmc8L2Rpdj4KICAgICAgICA8L2Rpdj4KICAgICAgICA8ZGl2PnZzPC9kaXY+CiAg ICAgICAgPGRpdiBjbGFzcz0icGFyZW50IiBzdHlsZT0iYmFja2dyb3VuZDogcmdiKDAsMjU1LDI1 NSkiPgogICAgICAgICAgICA8ZGl2IGNsYXNzPSJibGVuZGVkIGFjY2VsZXJhdGVkIiBzdHlsZT0i YmFja2dyb3VuZDogcmdiKDI1NSwwLDI1NSkiPkFjY2VsZXJhdGVkIGJsZW5kaW5nPC9kaXY+CiAg ICAgICAgPC9kaXY+CiAgICAgICAgPGRpdj52czwvZGl2PgogICAgICAgIDxkaXYgY2xhc3M9InBh cmVudCIgc3R5bGU9ImJhY2tncm91bmQ6cmdiKDI1NSwgMjU1LCAwKSI+RXhwZWN0ZWQgY29sb3I8 L2Rpdj4KICAgIDwvZGl2PgogICAgPGRpdiBjbGFzcz0icm93Ij4KICAgICAgICA8cD5hcXVhICgw LDI1NSwyNTUpID0gKDI1NSwwLDI1NSkgZGlmZmVyZW5jZSAoMjU1LDI1NSwwKTwvcD4KICAgICAg ICA8ZGl2IGNsYXNzPSJwYXJlbnQiIHN0eWxlPSJiYWNrZ3JvdW5kOiByZ2IoMjU1LDI1NSwwKSI+ CiAgICAgICAgICAgIDxkaXYgY2xhc3M9ImJsZW5kZWQiIHN0eWxlPSJiYWNrZ3JvdW5kOiByZ2Io MjU1LDAsMjU1KSI+Tm9uLWFjY2VsZXJhdGVkIGJsZW5kaW5nPC9kaXY+CiAgICAgICAgPC9kaXY+ CiAgICAgICAgPGRpdj52czwvZGl2PgogICAgICAgIDxkaXYgY2xhc3M9InBhcmVudCIgc3R5bGU9 ImJhY2tncm91bmQ6IHJnYigyNTUsMjU1LDApIj4KICAgICAgICAgICAgPGRpdiBjbGFzcz0iYmxl bmRlZCBhY2NlbGVyYXRlZCIgc3R5bGU9ImJhY2tncm91bmQ6IHJnYigyNTUsMCwyNTUpIj5BY2Nl bGVyYXRlZCBibGVuZGluZzwvZGl2PgogICAgICAgIDwvZGl2PgogICAgICAgIDxkaXY+dnM8L2Rp dj4KICAgICAgICA8ZGl2IGNsYXNzPSJwYXJlbnQiIHN0eWxlPSJiYWNrZ3JvdW5kOnJnYigwLCAy NTUsIDI1NSkiPkV4cGVjdGVkIGNvbG9yPC9kaXY+CiAgICA8L2Rpdj4KICAgIDxkaXYgY2xhc3M9 InJvdyI+CiAgICAgICAgPHA+Ymx1ZSAoMCwwLDI1NSkgPSAoMCwyNTUsMCkgZGlmZmVyZW5jZSAo MCwyNTUsMjU1KTwvcD4KICAgICAgICA8ZGl2IGNsYXNzPSJwYXJlbnQiIHN0eWxlPSJiYWNrZ3Jv dW5kOiByZ2IoMCwyNTUsMjU1KSI+CiAgICAgICAgICAgIDxkaXYgY2xhc3M9ImJsZW5kZWQiIHN0 eWxlPSJiYWNrZ3JvdW5kOiByZ2IoMCwyNTUsMCkiPk5vbi1hY2NlbGVyYXRlZCBibGVuZGluZzwv ZGl2PgogICAgICAgIDwvZGl2PgogICAgICAgIDxkaXY+dnM8L2Rpdj4KICAgICAgICA8ZGl2IGNs YXNzPSJwYXJlbnQiIHN0eWxlPSJiYWNrZ3JvdW5kOiByZ2IoMCwyNTUsMjU1KSI+CiAgICAgICAg ICAgIDxkaXYgY2xhc3M9ImJsZW5kZWQgYWNjZWxlcmF0ZWQiIHN0eWxlPSJiYWNrZ3JvdW5kOiBy Z2IoMCwyNTUsMCkiPkFjY2VsZXJhdGVkIGJsZW5kaW5nPC9kaXY+CiAgICAgICAgPC9kaXY+CiAg ICAgICAgPGRpdj52czwvZGl2PgogICAgICAgIDxkaXYgY2xhc3M9InBhcmVudCIgc3R5bGU9ImJh Y2tncm91bmQ6cmdiKDAsIDAsIDI1NSkiPkV4cGVjdGVkIGNvbG9yPC9kaXY+CiAgICA8L2Rpdj4K PC9ib2R5Pgo=