The basic characteristics of PNG

PNG is a file format used especially for images. It is a free file format, meaning that it can be used by everyone in any way he wants it without paying any royalties to anyone. But this is not the main advantage of PNG, I would even call it a minor advantage, as the end-users do not quite feel it.

The PNG format was intended to be a replacement for the older PNG format and, in some ways, to the TIFF format. It’s mainly used in two areas: World Wide Web and image-editing.

On the Web, PNG is much better that GIF. It has included alpha-channels (meaning that the image can have variable transparency), gamma correction (Its correcting the brightness of the image on every machine, so that the image would always be the same) and two-dimensional interlacing (a method of progressive display). PNG has a better compression than GIF, but as the difference between them is minor (only 2-25 % difference), it’s not really a great advantage. Also, PNG has a great disadvantage compared to GIF: it doesn’t support animations, being initially created only as a single image format. There are formats like APNG and MNG that come with the purpose of enabling animation on PNG.

As PNG’s compression is lossless, it is widely used in image editing software, mainly for saving intermediate stages of editing. In such a way, due to the lossless compression and 48-bit color and 16-bit grayscale saving, saving, restoring and re-saving of a PNG image will give you the same result as the first image, in contrast with JPG, which will perpetually degrade image’s quality. Anyway, for the transmission of finished images, JPEG is better, as it can provide a good quality at a comparable small size. Also, comparing to TIFF’s Group Fax Compression or the JBIG format, it provides a far smaller quality than the TIFF.PNG is a raster format, meaning that it is simply a two-dimensional array of dots, every dot containing its color information. It is not a vector format, so when you will zoom it, you will see the square pixels, in contrast with vector format where it is possible to zoom virtually infinitely.