- From: Erik Dahlstrom <ed@opera.com>
- Date: Tue, 29 Jun 2010 13:18:01 +0200
- To: www-svg@w3.org
On Tue, 29 Jun 2010 12:43:33 +0200, Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de> wrote: > Hello www-svg, > > about arithmetic operation of feComposite is mentioned: > > 'If the arithmetic operation is chosen, each result pixel is computed > using > the following formula: > result = k1*i1*i2 + k2*i1 + k3*i2 + k4' > > What is especially i1 and i2? > My assumption is, that it is the value of the corresponding channel of > the input indicated by the attributes in for i1 and in2 for i2? > If this is correct, my suggestion is to add something like: > > ',where i1 and i2 indicate the corresponding pixel channel values of > the input images, indicated by the attributes in for i1 and in2 for i2, > and k1, k2, k3, k4 indicate the values of the attributes with the > same name.' Yes, the above is correct. > Another suggestion to improve the understanding of the > other operations is to add formulas for the other operations > as well. This can help authors a lot, because the original > article from Porter and Duff is not trivial to find for all readers, > for example currently here an online version: > http://keithp.com/~keithp/porterduff/p253-porter.pdf What other operations? Where in the spec? Are you suggesting adding all the porter-duff equations for 'over', 'xor' etc to the feComposite section? > Additional suggestion for the related example: > Add a generic font-family - > Instead of font-family="Verdana" use for example > font-family="Verdana, sans-serif" Cosmetic change, but yes I agree, it is better practice. Cheers /Erik -- Erik Dahlstrom, Core Technology Developer, Opera Software Co-Chair, W3C SVG Working Group Personal blog: http://my.opera.com/macdev_ed
Received on Tuesday, 29 June 2010 11:18:35 UTC