"miscellaneous update"

git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@1168 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 24 insertions, 1 deletions

diff --git a/pnmsmooth.html b/pnmsmooth.html
index 62f85cf3..0871ca1a 100644
--- a/pnmsmooth.html
+++ b/pnmsmooth.html
@@ -14,7 +14,6 @@ pnmsmooth - smooth out an image
 
 <B>pnmsmooth</B>
 [<b>-width=</b><i>cols</i>] [<b>-height=</b><i>rows</i>]
-[<B>-dump=</b><I>dumpfile</I>]
 [<I>pnmfile</I>] [<b>-size</b>]
 
 <p>Minimum unique abbreviations of options is acceptable.  You may use double
@@ -98,6 +97,30 @@ the modern Netpbm command line parser, so had an unconventional command line
 syntax.  Most importantly, you could not use an equal sign or double
 hyphens in the options.
 
+<p>Before Netpbm 10.49 (December 2009), there was a <b>-dump</b> option.
+This strange option caused <b>pnmsmooth</b> not to do any smoothing or
+produce any output image but instead write the convolution matrix it
+would have used, as PGM file such as <b>pnmconvol</b> used to use, to
+a file you specify.  The idea was you could then use that file with a
+separate invocation of <b>pnmconvol</b>.
+
+<p>Then, in Netpbm 10.49, there was a rather different <b>-dump</b>
+option with a similar purpose: It caused <b>pnmsmooth</b> to write to
+Standard Error a string suitable as a value for the <b>pnmconvol</b>
+<b>-matrix</b> option (an option that was new in Netpbm 10.49).
+
+<p>But in Netpbm 10.51 (June 2010), <b>pnmconvol</b> started using the even
+newer <b>pnmconvol</b> <b>-normalize</b> option (new in 10.50), which made
+specifying the convolution matrix for the kind of smoothing that
+<b>pnmsmooth</b> does trivial, so <b>-dump</b> disappeared from
+<b>pnmsmooth</b>.
+
+<p>(There were also ease of implementation issues that kept us from simply
+keeping the original <b>-dump</b> around for backward compatibility: As we
+modified <b>pnmsmooth</b> to take advantage of the new features of
+<b>pnmconvol</b>, which <b>pnmsmooth</b> uses internally, the information
+needed to implement <b>-dump</b> was no longer available in the program).
+
 <HR>
 <H2 id="index">Table Of Contents</H2>
 <UL>