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| author | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2007-01-06 18:36:51 +0000 |
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| committer | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2007-01-06 18:36:51 +0000 |
| commit | dda70aa897a9e1d30f7deff7a2628b0f62ebf2f1 (patch) | |
| tree | eb8515e7620ef8fdcfbbb34107b7d4210197e23b /pamfixtrunc.html | |
| parent | d425be9069c100ff16e21373d161b0b4b1e323f1 (diff) | |
| download | netpbm-mirror-dda70aa897a9e1d30f7deff7a2628b0f62ebf2f1.tar.gz netpbm-mirror-dda70aa897a9e1d30f7deff7a2628b0f62ebf2f1.tar.xz netpbm-mirror-dda70aa897a9e1d30f7deff7a2628b0f62ebf2f1.zip | |
"miscellaneous update"
git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@197 9d0c8265-081b-0410-96cb-a4ca84ce46f8
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1 files changed, 90 insertions, 0 deletions
diff --git a/pamfixtrunc.html b/pamfixtrunc.html new file mode 100644 index 00000000..14b8477d --- /dev/null +++ b/pamfixtrunc.html @@ -0,0 +1,90 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML><HEAD><TITLE>Pamfixtrunc User Manual</TITLE></HEAD> +<BODY> +<H1>pamfixtrunc</H1> +Updated: 06 January 2006 +<BR> +<A HREF="#index">Table Of Contents</A> + +<H2>NAME</H2> + +pamfixtrunc - repair a Netpbm image whose file is truncated + +<H2 id="synopsis">SYNOPSIS</H2> + +<B>pamfixtrunc</B> + +[<b>-verbose</b>] + +[<I>netpbmfile</I>] + +<H2 id="description">DESCRIPTION</H2> + +<p>This program is part of <a href="index.html">Netpbm</a>. + +<p><b>pamfixtrunc</b> reads as much as it can of a Netpbm image +that may be truncated (i.e. the file may not contain the last part +of the image) and writes out a valid Netpbm image that is just +missing the bottom rows of the original (pre-truncation) image. + +<p>The header of a Netpbm image implies how large the image must +be (how many bytes the file must contain). If the file is actually +smaller than that, a Netpbm program that tries to read the image +fails, with an error message telling you that it couldn't read the +whole file. The data in the file is arranged in row order, from +top to bottom, and the most common reason for the file being smaller +than its header says it should be is because the bottommost rows are +simply missing. So <b>pamfixtrunc</b> assumes that is the case +and generates a new image with just the rows that are readable. +(technically, that means the output's header indicates a smaller +number of rows and omits any partial last row). + +<p>The most common way for a Netpbm file to be small is that something +interrupted the program that generated it before it was finished writing +the file. For example, the program ran out of its own input or +encountered a bug or ran out of space in which to write the output. + +<p>Another problem <b>pamfixtrunc</b> deals with is where the file isn't +actually too small, but due to a system error, a byte in the middle of +it cannot be read (think of a disk storage failure). <b>pamfixtrunc</b> +reads the input sequentially until it can't read any further, for any +reason. So it treats such an image as a truncated one, ignoring all +data after the unreadable byte. + +<p>But be aware that an image file is sometimes too small because of a +bug in the program that generated it, and in that case it is not +simply a matter of the bottom of the image missing, so +<b>pamfixtrunc</b> simply creates a valid Netpbm image containing a +garbage picture. + +<p><b>pamfixtrunc</b> looks at only on the first image in a multi-image +stream. + +<p>If you want to test an image file to see if it is corrupted by being +too small, use <b>pamfile --allimages</b> . It fails with an error +message if the file is too small. + +<p>If you want to cut the bottom off a valid Netpbm image, use +<b>pamcut</b>. + +<H2 id="seealso">SEE ALSO</H2> + +<A HREF="pnm.html">pnm</A>, +<A HREF="pam.html">pam</A>, +<A HREF="pamcut.html">pamcut</A>, +<A HREF="pamfile.html">pamfile</A>, + +<h2 id="history">HISTORY</h2> + +<p><b>pamfixtrunc</b> was new in Netpbm 10.38 (March 2007). + +<HR> +<H2 id="index">Table Of Contents</H2> +<UL> +<LI><A HREF="#synopsis">SYNOPSIS</A> +<LI><A HREF="#description">DESCRIPTION</A> +<LI><A HREF="#seealso">SEE ALSO</A> +<LI><A HREF="#history">HISTORY</A> +</UL> +</BODY> +</HTML> |