Truth is, I don't even remember who the argument was with - I just remember being annoyed. Thanks Ivan.
Ron Ganbar email: [email protected] tel: +44 (0)7968 007 309 [UK] +972 (0)54 255 9765 [Israel] url: http://ronganbar.wordpress.com/ On 15 November 2011 19:57, Ivan Busquets <[email protected]> wrote: > I hope there was a bet involved... :) > > If you need further proof, you could use this script: > > set cut_paste_input [stack 0] > version 6.2 v4 > BackdropNode { > inputs 0 > name BackdropNode2 > tile_color 0x7171c600 > label BG > note_font_size 42 > selected true > xpos 2434 > ypos 13246 > bdheight 156 > } > BackdropNode { > inputs 0 > name BackdropNode3 > tile_color 0x8e8e3800 > label "Convert back to linear\n\n(assuming your destination\napp will > convert\nto sRGB when importing)" > note_font_size 22 > selected true > xpos 2103 > ypos 14009 > bdwidth 286 > bdheight 218 > } > BackdropNode { > inputs 0 > name BackdropNode4 > tile_color 0x8e8e3800 > label Compare > note_font_size 42 > selected true > xpos 2613 > ypos 13944 > bdwidth 360 > bdheight 167 > } > BackdropNode { > inputs 0 > name BackdropNode1 > tile_color 0x8e8e3800 > label FG > note_font_size 42 > selected true > xpos 2191 > ypos 13222 > bdheight 190 > } > add_layer {rgba redguard1.glow} > ColorWheel { > inputs 0 > gamma 0.45 > name A > selected true > xpos 2201 > ypos 13300 > } > Blur { > size 100 > name Blur46 > selected true > xpos 2201 > ypos 13374 > } > Dot { > name Dot30 > selected true > xpos 2235 > ypos 13479 > } > set N18ce1090 [stack 0] > CheckerBoard2 { > inputs 0 > name B > selected true > xpos 2444 > ypos 13326 > } > set Nd0e8d830 [stack 0] > Dot { > name Dot31 > selected true > xpos 2478 > ypos 13639 > } > set N985ce2a0 [stack 0] > Colorspace { > colorspace_out sRGB > name Colorspace2 > selected true > xpos 2444 > ypos 13704 > } > set Ned256de0 [stack 0] > Merge2 { > inputs 2 > operation stencil > name Merge100 > label B*(1-a) > selected true > xpos 2444 > ypos 13852 > } > push $N18ce1090 > push $N985ce2a0 > Merge2 { > inputs 2 > name Merge101 > selected true > xpos 2207 > ypos 13634 > } > Colorspace { > colorspace_out sRGB > name Colorspace1 > selected true > xpos 2207 > ypos 13698 > } > Merge2 { > inputs 2 > operation from > name Merge102 > selected true > xpos 2207 > ypos 13857 > } > set Nd30cc020 [stack 0] > Unpremult { > name Unpremult4 > selected true > xpos 2207 > ypos 14144 > } > Colorspace { > colorspace_in sRGB > name Colorspace3 > selected true > xpos 2207 > ypos 14168 > } > Premult { > name Premult6 > selected true > xpos 2207 > ypos 14196 > } > Write { > name Write2 > label "write out here\n" > selected true > xpos 2207 > ypos 14263 > } > push $Nd30cc020 > push $Ned256de0 > Dot { > name Dot32 > selected true > xpos 2657 > ypos 13709 > } > Merge2 { > inputs 2 > name Merge103 > label "Comped in sRGB space" > selected true > xpos 2623 > ypos 14057 > } > push $N18ce1090 > Dot { > name Dot33 > selected true > xpos 2755 > ypos 13479 > } > push $Nd0e8d830 > Dot { > name Dot34 > selected true > xpos 2917 > ypos 13354 > } > Merge2 { > inputs 2 > name Merge104 > label "Comped in linear" > selected true > xpos 2883 > ypos 14024 > } > Colorspace { > colorspace_out sRGB > name Colorspace4 > label "Post sRGB conversion" > selected true > xpos 2883 > ypos 14066 > > } > > > On Tue, Nov 15, 2011 at 12:30 AM, Ron Ganbar <[email protected]> wrote: > >> I knew I was right. (You guys just proved an old argument I had with >> someone). >> Oh, the joys of self gratification. >> >> >> Ron Ganbar >> email: [email protected] >> tel: +44 (0)7968 007 309 [UK] >> +972 (0)54 255 9765 [Israel] >> url: http://ronganbar.wordpress.com/ >> >> >> >> On 15 November 2011 10:28, Ivan Busquets <[email protected]> wrote: >> >>> Hi Gavin, >>> >>> As you said yourself, the equation cannot be solved UNLESS you know both >>> variables on one of the sides. >>> In other words, you'd need to have the BG image in order to prep a FG >>> image so it can be comped in sRGB space and match the results of a linear >>> comp. >>> >>> So is there no way to output a PSD or PNG or TIFF which will look the >>>> same as my composite in Nuke over a white background? >>> >>> >>> If you need to get the same results on a white background, you could >>> prep your FG element such that: >>> >>> X = ( (FG * alpha + (1 - alpha)) ^ 2.2 - (1 - alpha) / alpha ) ^ >>> (1/2.2) >>> >>> Where X is the FG image you'd want to export to be comped on a white BG. >>> But of course, this will only give you a match when comping the FG over a >>> WHITE BG. If the BG changes, then you'd need to prep a different FG to go >>> with it. >>> >>> Hope that helps. >>> >>> Cheers, >>> Ivan >>> >>> >>> >>> On Mon, Nov 14, 2011 at 12:13 PM, Gavin Greenwalt < >>> [email protected]> wrote: >>> >>>> How are Nuke users handling workflows in which they need to deliver >>>> images with alpha that will be composited in sRGB space not linear space? >>>> >>>> Essentially we have a situation where you would need to find equations >>>> for u and v such that (xy + z(1-y))^(1-2.2) = (uv + z^(1-2.2)(1-v)). >>>> >>>> My initial impression is that it's impossible since the simplified >>>> version of this conundrum would be (x+y)^2 = (u+v) which I believe is >>>> mathematically impossible to solve... right? So is there no way to output >>>> a PSD or PNG or TIFF which will look the same as my composite in Nuke over >>>> a white background? >>>> >>>> Thanks, >>>> Gavin >>>> >>>> _______________________________________________ >>>> Nuke-users mailing list >>>> [email protected], http://forums.thefoundry.co.uk/ >>>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>>> >>> >>> >>> _______________________________________________ >>> Nuke-users mailing list >>> [email protected], http://forums.thefoundry.co.uk/ >>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>> >> >> >> _______________________________________________ >> Nuke-users mailing list >> [email protected], http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >> > > > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >
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