1. PNG Introduction

Portable Network Graphics (PNG) is a bitmapped image format that employs lossless data compression. PNG was created to improve upon and replace the GIF format, as an image-file format not requiring a patent license. PNG is pronounced “ping” (/pɪŋ/ in IPA). 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 truecolor images are supported, plus an optional alpha channel for transparency. Sample depths range from 1 to 16 bits per component (up to 48bit images for RGB, or 64bit for RGBA).

PNG supports palette-based (palettes of 24-bit RGB colors) or greyscale or RGB images. PNG was designed for transferring images on the Internet, not professional graphics, and so does not support other color spaces (such as CMYK).

PNG files nearly always use file-extension “PNG” or “png” and are assigned MIME media type “image/png” (approved October 14, 1996).

(The PNG image format is NOT Related to the country Papua New Guinea, the Pawnee National Grassland, the Professional Numismatists Guild or the “Pack ‘N’ Go” format)