Portable Network Graphics

Portable Network Graphics (.png) is an extensible file format for the lossless, portable, well-compressed storage of raster images. PNG provides a patent-free replacement for GIF and can also replace many common uses of TIFF. Indexed color, grayscale and RGB images are supported, plus an optional alpha channel. Sample depths range from 1 to 64 bits per pixel, supporting up to 48-bit RGB color with a 16-bit alpha channel.

Description

PNG is designed for online viewing applications, such as the World Wide Web, so it is fully streamable with a progressive display option. PNG is robust, providing both full file integrity checking and simple detection of common transmission errors. Also, PNG can store gamma correction and chromaticity data for improved color matching on various platforms.

"Minified" PNGs

PNGs normally support alpha channels to support transparency at 8 or 16-bits per pixel. However, it is also possible to create a "minified" 8-bit indexed color image with a "cheap" alpha channel; though this format is supported in most modern web browsers, it has not been as widely supported by graphics software until relatively recently.

See also

• SVG (Scalable Vector Graphics), for online vector images.

External links

• PNG (Portable Network Graphics) at the World Wide Web Consortium
• Portable Network Graphics (PNG) Specification and Extensions by Greg Roelofs
• PNG tech: Technical articles on the PNG file format at SourceForge
• Portable Network Graphics at the Adobe Wiki
• Portable Network Graphics at Wikipedia

Online PNG tools

• Compress PNG
• PNG Compressor at Gift of Speed
• PNG minifier at Photopea
• TinyPNG

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This page uses GFDL licensed content from the Free On-line Dictionary of Computing.