PNG or portable network graphic
Definition and characteristics
PNG means portable network graphic. The PNG format is one of the most common formats on the Internet for a pixel graphic whose compression should be loss-free. PNG images have a larger data volume than JPG files. Compared to TIFF, they are less complex, support different colour depths and, unlike JPG images, allow transparency.
A greyscale image can have a resolution of 16, 8, 4, 2 or 1 bit per pixel. Colour images consist of 16 or 8 bits depending on the colour channel. Alternatively, coloured images can be saved with a maximum of 256 colour tones, whereby these can be freely selected from the entire RGB 8 spectrum.
Transparency information is available as singular transparent colours or as an alpha channel. The transparency of channels can be determined with a value between 0 and 255. 255 corresponds to complete background coverage, 0 stands for 100% transparency.
Advantages and disadvantages
Irregularly shaped objects can be displayed freely as well as on any background. A box in white or other colour appears around the image. Due to the lossless compression, much more information can be saved than with a JPG file.
However, websites with many PNG images require longer loading times than with JPG. The PNG format is not suitable for printing because only the RGB colour space is covered and the CMYK model is required for print products.
