It seems that filterRes is deprecated in the spec (http://dev.w3.org/fxtf/filters/). Quote: "... filterRes attribute was removed from the specification. See SVG 1.1 specification for the definition". Finally FF has removed it already. It makes sense to remove this feature.
*** Bug 124914 has been marked as a duplicate of this bug. ***
I stumbled upon very similar problems with SVG Filters that are rendered in Safari in viewport pixels, disregarding device pixels on 'retina' devices. This was reported in Bug 124914 and in a somewhat related discussion in Bug 93471. I am also using filterRes to get sharp images on retina images. I have a test-page attached. The HTML is: <img src="filtered.svg" width="400"> and filtered.svg has a width of 800px for clients with DPR=2. as soon as a filter is used in the SVG it appears blurry in the browser. i can fix that by repeating the (desired) dimensions as filterRes in the svg: <svg .... width="800" height="531" ...> .. <filter filterRes="800 531" id="noop"> ... I don't know of any other workaround to make filters apply on a canvas regarding the dpr. If there is a better and more compliant way, please let me know. However, as long as I need this workaround, I would like to discourage you to drop filterRes. That said, I think that it is a bug in webkit, that the actual canvas size for filters is (presumably) derived from the targeted viewport area. Other browsers (Chrome and Firefox) that have already dropped filterRes support do not show this behavior. Please use the attached test-page svg-filter.tgz to verify it.
Created attachment 266897 [details] test-page to show effect of filterRes on retina clients
<rdar://problem/44714340>
Created attachment 350573 [details] Patch
Comment on attachment 350573 [details] Patch Attachment 350573 [details] did not pass mac-ews (mac): Output: https://webkit-queues.webkit.org/results/9322431 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg html5lib/generated/run-tests11-write.html imported/w3c/web-platform-tests/html/syntax/parsing/html5lib_tests11.html html5lib/generated/run-tests11-data.html svg/dom/SVGAnimatedInteger.html
Created attachment 350578 [details] Archive of layout-test-results from ews100 for mac-sierra The attached test failures were seen while running run-webkit-tests on the mac-ews. Bot: ews100 Port: mac-sierra Platform: Mac OS X 10.12.6
Comment on attachment 350573 [details] Patch Attachment 350573 [details] did not pass mac-wk2-ews (mac-wk2): Output: https://webkit-queues.webkit.org/results/9322448 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg html5lib/generated/run-tests11-write.html imported/w3c/web-platform-tests/html/syntax/parsing/html5lib_tests11.html html5lib/generated/run-tests11-data.html svg/dom/SVGAnimatedInteger.html
Created attachment 350580 [details] Archive of layout-test-results from ews104 for mac-sierra-wk2 The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews. Bot: ews104 Port: mac-sierra-wk2 Platform: Mac OS X 10.12.6
Comment on attachment 350573 [details] Patch Attachment 350573 [details] did not pass win-ews (win): Output: https://webkit-queues.webkit.org/results/9322571 New failing tests: html5lib/generated/run-tests11-write.html html5lib/generated/run-tests11-data.html svg/dom/SVGAnimatedInteger.html svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg
Created attachment 350582 [details] Archive of layout-test-results from ews202 for win-future The attached test failures were seen while running run-webkit-tests on the win-ews. Bot: ews202 Port: win-future Platform: CYGWIN_NT-6.1-2.10.0-0.325-5-3-x86_64-64bit
Comment on attachment 350573 [details] Patch Attachment 350573 [details] did not pass mac-debug-ews (mac): Output: https://webkit-queues.webkit.org/results/9322499 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg html5lib/generated/run-tests11-write.html imported/w3c/web-platform-tests/html/syntax/parsing/html5lib_tests11.html html5lib/generated/run-tests11-data.html svg/dom/SVGAnimatedInteger.html
Created attachment 350585 [details] Archive of layout-test-results from ews116 for mac-sierra The attached test failures were seen while running run-webkit-tests on the mac-debug-ews. Bot: ews116 Port: mac-sierra Platform: Mac OS X 10.12.6
Comment on attachment 350573 [details] Patch Attachment 350573 [details] did not pass ios-sim-ews (ios-simulator-wk2): Output: https://webkit-queues.webkit.org/results/9322506 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg html5lib/generated/run-tests11-write.html imported/w3c/web-platform-tests/html/syntax/parsing/html5lib_tests11.html html5lib/generated/run-tests11-data.html svg/dom/SVGAnimatedInteger.html
Created attachment 350586 [details] Archive of layout-test-results from ews121 for ios-simulator-wk2 The attached test failures were seen while running run-webkit-tests on the ios-sim-ews. Bot: ews121 Port: ios-simulator-wk2 Platform: Mac OS X 10.13.6
Comment on attachment 350573 [details] Patch Attachment 350573 [details] did not pass mac-debug-ews (mac): Output: https://webkit-queues.webkit.org/results/9323346 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg html5lib/generated/run-tests11-write.html imported/w3c/web-platform-tests/html/syntax/parsing/html5lib_tests11.html html5lib/generated/run-tests11-data.html svg/dom/SVGAnimatedInteger.html
Created attachment 350589 [details] Archive of layout-test-results from ews113 for mac-sierra The attached test failures were seen while running run-webkit-tests on the mac-debug-ews. Bot: ews113 Port: mac-sierra Platform: Mac OS X 10.12.6
Comment on attachment 350573 [details] Patch Attachment 350573 [details] did not pass ios-sim-ews (ios-simulator-wk2): Output: https://webkit-queues.webkit.org/results/9323436 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg html5lib/generated/run-tests11-write.html imported/w3c/web-platform-tests/html/syntax/parsing/html5lib_tests11.html html5lib/generated/run-tests11-data.html svg/dom/SVGAnimatedInteger.html
Created attachment 350592 [details] Archive of layout-test-results from ews123 for ios-simulator-wk2 The attached test failures were seen while running run-webkit-tests on the ios-sim-ews. Bot: ews123 Port: ios-simulator-wk2 Platform: Mac OS X 10.13.6
Created attachment 350601 [details] Patch
Comment on attachment 350601 [details] Patch Attachment 350601 [details] did not pass win-ews (win): Output: https://webkit-queues.webkit.org/results/9326123 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg
Created attachment 350603 [details] Archive of layout-test-results from ews202 for win-future The attached test failures were seen while running run-webkit-tests on the win-ews. Bot: ews202 Port: win-future Platform: CYGWIN_NT-6.1-2.10.0-0.325-5-3-x86_64-64bit
Comment on attachment 350601 [details] Patch Attachment 350601 [details] did not pass ios-sim-ews (ios-simulator-wk2): Output: https://webkit-queues.webkit.org/results/9326105 New failing tests: svg/W3C-SVG-1.1-SE/svgdom-over-01-f.svg
Created attachment 350607 [details] Archive of layout-test-results from ews121 for ios-simulator-wk2 The attached test failures were seen while running run-webkit-tests on the ios-sim-ews. Bot: ews121 Port: ios-simulator-wk2 Platform: Mac OS X 10.13.6
Created attachment 350608 [details] Patch
Comment on attachment 350608 [details] Patch Clearing flags on attachment: 350608 Committed r236447: <https://trac.webkit.org/changeset/236447>
All reviewed patches have been landed. Closing bug.