Reputedly an excellent set of resources for using libpng - but don’t take my word for it - my Japanese is non-existent.

http://www5.cds.ne.jp/~kato/png/

I can’t imagine a better description of this product than is found on the first line of their web page: “PNGwriter is a C++ class for creating PNG images.” And yes, it’s a free library, and it’s portable as all get-out, working on Win32, Linux, Mac OS X, and more.

Version 0.4.0 shipped in June, 2004.

http://pngwriter.sourceforge.net/

Sixlegs PNG Library is a Java 1.1-compatible PNG decoder which features full compliance with the latest PNG specification. It supports all valid bit depths (grayscale/color), interlacing, palette-indexed images, alpha/transparency, gamma correction, access to all standard chunk data, private chunk handling, progressive display, and more

http://sixlegs.com/software/png/

PNG/MNG Construction Set represents the state of the art in animation software. It will assemble your original animations effortlessly through its Animation Wizard, squeeze them down to as close to nothing as possible with its Supercompressor; create eyecatching banners and animated transitions; manage your MNG files; add transparency to existing PNG graphics and a lot more.

Version 2.0.25 is shipping as of June, 2004.

http://www.mindworkshop.com/alchemy/pngpro.html

About.com gives their explanation of what this is.

http://graphicssoft.about.com/library/weekly/aa121699d.htm

SIP intends to do imaging tasks such as filtering, blurring, edge detection, thresholding, histogram manipulation, segmentation, mathematical morphology, color image processing, etc.
These operations are useful for problem solving in real-world applications ranging from car motion planning to automatic diagnosis of medical images.

Version 0.3.1 is shipping as of May, 2004.

http://siptoolbox.sourceforge.net/

OptiPNG is a PNG optimizer that recompresses the image files to a smaller size, without losing any information.
The idea behind this program has been inspired from pngcrush (http://pmt.sourceforge.net/pngcrush), and is explained in detail in the PNG-Tech article “A guide to PNG optimization”

http://www.cs.toronto.edu/~cosmin/pngtech/optipng/

This site is dedicated to open source QuickTime development for popular open source audio and video codecs. We are currently working on Ogg Vorbis, an audio codec developed by Xiphophorus, and MNG, an animation video codec.

http://qtcomponents.sourceforge.net/

This package is used to read DVI files created by TeX et.al. and convert them to PNG files. It claims to be quite fast.

Version 1.0 is shipping as of March 29, 2004.

http://freshmeat.net/projects/dvipng

2PNG is a graphics converter allowing you to convert images to png format from 50+ image file types including conversions from jpeg to png, from gif to png, from tiff to png and so on. (See the full list of supported formats here.) The program has no windows interface and is fully optimized for working in background mode

http://batch.fcodersoft.com/2png/index.htm

A visual tool that lets you degrade image files with visual feedback on how you are doing. A good, easy way to minimize the size of files before using them on your web page, tec.

http://optimizer.sourceforge.net/

SNG (Scriptable Network Graphics) is a minilanguage designed specifically to represent the entire contents of a PNG (Portable Network Graphics) file in an editable form. Thus, SNGs representing elaborate graphics images and ancillary chunk data can be readily generated or modified using only text tools.

Version 1.0.2 shipped in November, 2003.

http://sng.sourceforge.net/

Arcsoft has a line of mobile media codecs that includes support for MIDI, JPEG, PNG, GIF, and speech.

http://www.arcsoft.com/en/wireless/corelibraries.asp

Convert your GIF files to PNG format under UNIX, Linux, or Win32.

http://www.catb.org/~esr/gif2png/

Pngmeta is a tool for extracting metadata from PNG files. This is freeware.

http://pmt.sourceforge.net/pngmeta/index.html

Convert back and forth between PNG and BMP. Freeware.

http://pmt.sourceforge.net/bmp2png/index.html

This Code Project article is pretty much summed up by its descriptive title. It appears to use the .NET framework to store images in PNG format.

http://codeproject.com/useritems/PNGUploader.asp

The MNG file format exists to provide a way to create animated graphics based on the PNG format. Programs that want an easy way to display and manipulate mng format files can use libmng, which is found here.

Version 1.0.5 of libmng is shipping as of March, 2003. TNGImage 1.2 (the Delphi Wrapper for libmng) shipped in April, 2003.

http://libmng.sourceforge.net/

Kazuo Adachi ported both of these important packages to Windows CE and Windows CE .Net. This includes binaries for what I believe are all the currently support CPUs.

http://www.tenik.co.jp/~adachi/wince/

“Compressed Image File Formats is an appealingly compact and useful guide to some of today’s most popular file formats used for image data. For any programmer who needs to know how images are stored, this concise reference can serve as a really invaluable resource.”
Note that the source code for this book includes an independent implementation of a PNG codec, which may be one of a kind. Link to the source code on this page.

Please use
this link to purchase the book through Amazon.com. Your purchase will help support this web site.

http://www.colosseumbuilders.com/imageformats/compressedimageformats.htm

A complete short course on digital photography from Agfa. It shows up here because Lesson 6 is on The Right Compression. You get a discussion of various formats, including GIF, JPEG, JPEG2K, and PNG. Best of all, it looks like the entire page is available in English, German, Spanish, and Portuguese.

http://www.agfanet.com/en/cafe/photocourse/digicourse/cont_index.php3

A tutorial page discussing the various image formats currently in use on the web. Nice comparisons and a good set of links.

http://www.psychology.nottingham.ac.uk/staff/cr1/graphics.html

The Wikipedia entry for PNG. Good overview with many relevant links to other entries in the Wikipedia.

http://en.wikipedia.org/wiki/Png

The Wikipedia entry for MNG. Fairly terse..

http://en.wikipedia.org/wiki/MNG

This site contains a collection of comments, impressions, comparisons, experiments and ideas regarding the PNG (Portable Network Graphics) file format, and related technologies: zlib (Data Compression Library), and MNG (Multiple-image Network Graphics). It is focused especially on the compression algorithms used in PNG.

http://www.cs.toronto.edu/~cosmin/pngtech/

From the site: Pngcrush is an optimizer for PNG (Portable Network Graphics) files. It can be run from a commandline in an MSDOS window, or from a UNIX or LINUX commandline. .

http://pmt.sourceforge.net/pngcrush/

Want to know how things are going in the world of PNG? Come check this page from time to time. See the current ratings for Stability, User Acceptance, Application Support, and so on.

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

AOL’s search page dedicated to the PNG format

http://search.aol.com/cat.adp?from=catsearch&id=112910

Greg Roelofs tells the story of PNG. If anyone should know, it would be the wise man known as Cave Newt.

http://www.libpng.org/pub/png/slashpng-1999.html

This ftp site appears to contain a ton of MNG documentation, specs, etc. This is the official ftp site for the MNG project, the web pages are still being hosted at the www.cdrom.com site.

ftp://swrinde.nde.swri.edu/pub/mng/documents/