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-rw-r--r-- | pamarith.html | 16 |
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diff --git a/pamarith.html b/pamarith.html index 0f300048..7127bc89 100644 --- a/pamarith.html +++ b/pamarith.html @@ -39,11 +39,15 @@ output. <p>For functions that are commutative and associative, <b>pamarith</b> applies the binary function repetitively on as many input images as you supply. For - example, for <b>-add</b> , the output is the sum of all the inputs; for - <b>-equal</b>, it tells you whether all the inputs are equal. For other - functions (e.g. <b>-subtract</b>), the program fails if you supply more - than two input images. (Before Netpbm 10.51 (June 2010), the program always - failed with more than two input images). + example, for <b>-add</b> , the output is the sum of all the inputs. For + other functions (e.g. <b>-subtract</b>), the program fails if you supply + more than two input images. (Before Netpbm 10.93 (December 2020), the + program always failed with more than two input images). + +<p>For some other functions, <b>pamarith</b> could theoretically compute a + meaningful result for multiple arguments, but it fails nonetheless if you + give more than two input images. <b>-mean</b> and <b>-equal</b> are in that + category. <p>Most of what <b>pamarith</b> does is not meaningful for visual images. It works toward Netpbm's secondary purpose of just manipulating arbitrary @@ -322,7 +326,7 @@ that made it backward compatible with <b>pnmarith</b>. <p>The <b>-divide</b> option was added in Netpbm 10.30 (October 2005). <p>The ability to have more than one input (operand) was added in Netpbm -10.51 (June 2010), but not documented until October 2020. +10.93 (December 2020). <p>The <b>-equal</b> option was added in Netpbm 10.93 (December 2020). |