File talk:Comparison convolution james.png

If we assume that the two top rows are labeled correctly (with f's and g's), then the 3 red traces should all look identical, as they are at https://commons.wikimedia.org/wiki/File:Comparison_convolution_correlation.svg. The actual error is the $(f\star g)$ picture. It should look like $(f*g),$ because f(t) is symmetrical. Here I am relying on the definition at https://en.wikipedia.org/wiki/Cross-correlation:

$(f\star g)(\tau )\ {\stackrel {\mathrm {def} }{=}}\int _{-\infty }^{\infty }f(t)\ g(t+\tau )\,dt,$

Alternatively, the center picture should be re-labeled $(g\star f),$ which I have just done. It would therefore be nice if the first column depicted $(g*f)$ instead of $(f*g)$. They turn out to be identical, but the tiny illutrations at the bottom of the column are different.
--Bob K (留言) 17:12, 19 November 2016 (UTC)

I fixed the mislabeled case, and added the two missing cases that were causing confusion at https://en.wikipedia.org/wiki/Talk:Convolution.
--Bob K (留言) 18:59, 19 November 2016 (UTC)

I've ported the changes back to File:comparison_convolution_correlation.svg. Hope it's all right to revert the articles back to the SVG. Cheers, cmɢʟee⎆τaʟκ 19:13, 20 November 2016 (UTC)