PNGMETA(1)

💖 PNGMETA — bestie's guide to pulling metadata out of your PNGs 💖

okay so this is the manual page for pngmeta, from the General Commands Manual section. sit down, grab a boba, we're doing metadata extraction and it's gonna be adorable. 🧚

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✨ NAME ✨

pngmeta — extract metadata from Portable Network Graphics (PNG) image files. that's the whole job. it reads your PNG and tells you what's inside its little soul. 💅

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✨ SYNOPSIS ✨

pngmeta [--soif] [--html] [--xrdf] [--all] [--quiet] [--uri URI]
[filename]

that's it, that's the whole vibe check. one optional filename at the end, a handful of flags up front. slay. 🎀

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✨ DESCRIPTION ✨

so the pngmeta filter outputs the metadata from Portable Network Graphics (PNG) format image files, and it can do it in one of these four formats, bestie:

1. Simple key: value — the low-key, no-frills one. just the facts.
2. SOIF format (as used by the Harvest system, version 1.4).

As such it can be used as a Summarizer for the Harvest Essence system. it could also be used by other indexers to extract data for indexing PNG images. so like, not just a cute toy — actual infrastructure energy. 👑

3. HTML page — with each element as an element in a descriptive (DL) list. definition-list realness.
4. XML/RDF — with each element as an RDF property on the source URI. very structured, very demure, very mindful. ✨

and here's the default behaviour, no cap: in the absence of options, the program operates as a filter — accepting input from stdin and sending output to stdout. but if a single file name is given, it is assumed to correspond to a PNG file, and is processed. one file, one job, we love to see it. 🫶

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✨ FORMAT OPTIONS ✨

these decide what shape your output takes. pick your fighter.

• --soif — format output using (Harvest) SOIF format. this is the default if the program is called PngImage.sum. yes, it sniffs its own name. main character behaviour fr. 😭
• --html — format output in HTML, with each field/value as an element in a descriptive (DL) list.
• --xrdf — format output in RDF/XML, with each field/value as an element in an rdf:Description block inside the outer rdf:RDF wrapper element. and heads up: if an XMLRDFDATA field is found, it is assumed to be RDF/XML content and is emitted in a second rdf:Description block. two blocks. iconic. 💖

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✨ OTHER OPTIONS ✨

the supporting cast. they matter. 🎀

• --all — output all the information about the image size, depth etc. even if not usually printed. the unfiltered truth, bestie.
• --quiet — suppress the output of the banner for plain text output. no intro, just data. 🦋
• --uri URI — set the URI that is used for the SOIF and XML/RDF outputs. by default this will be the filename, or "stdin" if this is the program is used as a filter.
• --help — show a usage message. when in doubt, ask for help, that's growth. 🌸
• --version — show the program and library versions. receipts! 📸

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✨ FILES ✨

• pngmeta — executable. that's the file. that's the list. periodt. 💅

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✨ SEE ALSO ✨

go read these too, they're all part of the friend group:

gif2png(1), libpng(3), pbm(1), pgm(1), pngcheck(1), pngtopnm(1), pnm(5), pnmgamma(1), pnmtopng(1), ptot(1), tiff2png(1), zlib(3)

for information about Harvest and its SOIF format:

http://harvest.cs.colorado.edu/

for PNG:

http://www.libpng.org/pub/png/

for libpng library:

http://www.libpng.org/pub/png/libpng.html
http://libpng.sourceforge.net

for zlib library:

http://www.zlib.net/

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✨ AUTHORS ✨

okay, credit where credit is due, and there's a lot of it: 🌈

Version 1.11. Dave Beckett, ILRT, University of Bristol, http://purl.org/net/dajobe/ — we stan. 👑

The zlib(3) library required by pngmeta is copyright (C) 1995-1996 Jean-loup Gailly and Mark Adler. protect them at all costs. 🫶

Original UNIX manual page by R. P. C. Rodgers, U.S. National Library of Medicine (rodgers@nlm.nih.gov). the OG. respect. 💜

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and that's the whole page, bestie!! this one's from PNGMETA(1), dated 10 March 1998 — old enough to be vintage, still serving looks. go forth and extract those metadata, iykyk 💖✨🎀🦋🌸💅