PAMFIX(1)

💖 PAMFIX(1) — the pamfix girlie's guide 💖

okay bestie, welcome to the Pamfix User Manual, general commands manual energy, and honestly? she's a hero. 🫶

✨ NAME ✨

pamfix — repair a Netpbm image with various corruptions. literally a glow-up surgeon for broken files 💅

✨ SYNOPSIS ✨

pamfix

[-truncate] [-changemaxval] [-clip] [-verbose]

[netpbmfile]

ngl the CLI is chill: you only have to type enough of an option name to make it unique, that's the minimum unique abbreviation rule and yes it counts. you can also use double hyphens instead of a single one to denote options (no one's judging). and if you want to separate an option name from its value with white space instead of an equals sign? slay, go off. ✨

✨ DESCRIPTION ✨

so this program is part of Netpbm(1), periodt. 🌈

pamfix reads a stream that is mostly a Netpbm image but might have certain types of corruption in it, and produces a valid Netpbm image that preserves much of the info from the original. it's giving restoration arc, it's giving main character energy, honestly iconic.

in particular, Netpbm salvages streams that are truncated, and streams that contain illegally large sample values. 🚨

one thing to know: pamfix looks at only the first image in a multi-image stream. just the first one. the rest are background characters, sorry. 🙈

🌸 Truncated Stream 🌸

this is a stream that's missing its last part — like a text that got cut off mid-😭. Netpbm corrects this by creating an output image that simply has fewer rows. shorter king. shorter legend. 👑

you select this kind of repair with the -truncate option.

so like, the header of a Netpbm image implies how large the image must be (like, 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, and it hits you with an error message saying 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 a file being smaller than its header claims is that the bottommost rows are simply missing. so pamfix assumes that's what happened 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 — nerdy but cute.)

the most common way for a Netpbm file to be too small is that something interrupted the program that generated it before it finished writing the file. for example: the program ran out of its own input, or it encountered a bug, or it ran out of space to write the output. classic. 💀

another problem pamfix deals with is where the file isn't actually too small, but because of a system error, a byte in the middle of it cannot be read (think of a disk storage failure — the horror). pamfix 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. bye to everything past that byte, no cap. 🦋

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 pamfix simply creates a valid Netpbm image containing a garbage picture. yes. garbage. she's still valid, she's just... going through something. 🗑️✨

if you want to test an image file to see if it's corrupted by being too small, use pamfile --allimages. it fails with an error message if the file is too small. 🔍

if you want to cut the bottom off a valid Netpbm image, use pamcut. that's a different girlie with a different job. ✂️

🌸 Excessive Sample Value 🌸

this is a stream that contains a purported sample value that's higher than the maxval of the image. overachieving. over the limit. breaking the rules. 😳

the header of a Netpbm image tells the maxval of the image, which is a value that gives meaning to all the sample values in the raster. the sample values represent a fraction of the maxval, so a sample value that's greater than the maxval makes literally no sense. math said no. 🙅♀️

a regular Netpbm program fails if you give it input that contains a value larger than the maxval where a sample value belongs.

pamfix has three ways of salvaging such a stream:

• Clip to the maxval. request this with -clip. ✂️
• Raise the maxval, thus lowering the fraction represented by every sample in the image. request this with -changemaxval. 📈
• Truncate the image at the first invalid sample value. request this with -truncate and neither -clip nor -changemaxval. 🛑

you cannot specify both -clip and -changemaxval. pick a lane bestie, one or the other. 🚫

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✨ OPTIONS ✨

in addition to the options common to all programs based on libnetpbm (most notably -quiet, see Common Options), pamfix recognizes the following command line options:

• -truncate — create a truncated output image from all the valid input rows that could be read.
• -changemaxval — raise the maxval to cope with pixel values that exceed the maxval stated in the header of the input file.
• -clip — change all pixel values that exceed the maxval stated in the header of the input file.
• -verbose — report details of the transportation to standard error. yes, transportation. we ride. 🚗💨

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✨ SEE ALSO ✨

pnm(1), pam(1), pamcut(1), pamfile(1), pamvalidate(1)

the whole squad, linked, supporting each other. 🫶

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✨ HISTORY ✨

pamfix was new in Netpbm 10.66 (March 2014). but she grew out of pamfixtrunc, which was new in Netpbm 10.38 (March 2007) and did only the truncated image repair (and for invalid sample values would simply pass them through to its output, generating an invalid Netpbm image — messy era, we don't talk about it 💀).

so yeah, glow-up confirmed. from one-job pony to multi-talented icon. 👑

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✨ DOCUMENT SOURCE ✨

this manual page was generated by the Netpbm tool makeman from HTML source. the master documentation is at

http://netpbm.sourceforge.net/doc/pamfix.html

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💖 and that's the whole page bestie! this was brought to you by netpbm documentation, dated 06 March 2014, aka the Pamfix User Manual(1) — read it, love it, and go un-corrupt some pixels. mwah. 🎀✨🦋