Portable Network Graphics facts for kids
|
A PNG image with an 8-bit transparency channel, overlaid onto a checkered background, typically used in graphics software to indicate transparency
|
|
| Filename extension |
.png
|
|---|---|
| Internet media type |
image/png
|
| Type code | PNGf PNG |
| Uniform Type Identifier (UTI) | public.png |
| Magic number | 89 50 4e 47 0d 0a 1a 0a |
| Developed by | PNG Development Group (donated to W3C) |
| Initial release | 1 October 1996 |
| Type of format | Lossless bitmap image format |
| Extended to | APNG, JNG and MNG |
| Standard | ISO/IEC 15948, IETF RFC 2083 |
| Free format? | Yes |
Portable Network Graphics is a raster-graphics file-format that supports lossless data compression. PNG was developed as an improved, non-patented replacement for Graphics Interchange Format (GIF).
PNG supports palette-based images (with palettes of 24-bit RGB or 32-bit RGBA colors), grayscale images (with or without alpha channel for transparency), and full-color non-palette-based RGB or RGBA images. The PNG working group designed the format for transferring images on the Internet, not for professional-quality print graphics, and therefore it does not support non-RGB color spaces such as CMYK. A PNG file contains a single image in an extensible structure of "chunks", encoding the basic pixels and other information such as textual comments and integrity checks documented in RFC 2083.
PNG files nearly always use the file extension PNG or png and are assigned MIME media type image/png. PNG was published as informational RFC 2083 in March 1997 and as an ISO/IEC standard in 2004.
Images for kids
-
30px]] viewed with a hex editor application for Ubuntu.
-
A demonstration of the colour depth in a PNG file, in bits per channel. Left: 8 bits, Right: 16 bits. Note the artifacts, adjusted contrast for clarity.
-
Representation of bit cost per pixel for above PNG file (red=expensive, blue=cheap)
-
A PNG with 256 colors, which is only 251 bytes large with pre-filter. The same image as a GIF would be more than thirteen times larger.
-
An illustration of Adam7 interlacing over a 16×16 image.
-
An APNG (animated PNG) file (displays as static image in some web browsers)
-
Composite image comparing lossy compression in JPEG with lossless compression in PNG: the JPEG artifacts can be easily visible in the background of this kind of image data, where the PNG image has solid color.
See also
In Spanish: Portable Network Graphics para niños
