- Portable Network Graphic ('ping') - is a raster graphics file format that supports lossless data compression. PNG was created as an improved, non-patented replacement for Graphics Interchange Format (GIF), and is the most widely used lossless image compression format on the Internet.
- 8-bit, 24-bit, 32-bit color
- alpha channel
- PNG file size can vary significantly depending on how it is encoded and compressed
- Color depth
Color depth can range from 1 to 64 bits per pixel.
- Ancillary chunks
PNG supports metadata—this may be useful for editing, but unnecessary for viewing, as on websites.
- Interlacing
As each pass of the Adam7 algorithm is separately filtered, this can increase file size.
- Filter
As a precompression stage, each line is filtered by a predictive filter, which can change from line to line. As the ultimate DEFLATE step operates on the whole image's filtered data, one cannot optimize this row-by-row; the choice of filter for each row is thus potentially very variable, though heuristics exist
- Compression
With additional computation, DEFLATE compressors can produce smaller files.
- PNG pitfalls
- Generally larger file size
- Limited support on older browsers - much older browsers (IE6)