What exactly is PNG?
First, this article is from my curious during my Image processing class. So, I’m just a student that searched about these stuffs and concluded them in my understanding.
PNG stands for “Portable Network Graphic”. According to the history of PNG format, we had to travel back to 1995 when the first draft had been developed by “PNG Development Group”
The purpose of PNG format is designed for replacing GIF format files because of LZW compression’s patent, which expired on June 20 2003. Thus, the new compress algorithm called “DEFLATE (LZ77)” was created.
“PNG don’t have background color?”
Do you know that PNG format has the extra channel that called “alpha”? This channel is used for transparency that are included in pixel value. It will perform this transparency effect when the other pixels are placed over by the alpha channel and it has 16 maximum bits depth.
So, PNG image has the background color but it can transparency by alpha channel.
“PNG and GIF”
PNG format has similarity to GIF format but it cannot create the simple animation as GIF’s ability, that uses multiple images. Meanwhile, PNG format supports 24-bit color RGB but GIF supports only 8-bit color which creating better quality in a single PNG image than the GIF one.
The biggest issue of PNG format comparing to JPEG file is the size of big file. In term of full quality of 24-bit PNG file, it is bigger than twice of 24-bit JPEG file because of lossless compression algorithm.
However, PNG format is not designed for replacing JPEG format. It was created using lossless compression format and transparency channel which is best served in small files on the website.
“You can read more about the history of PNG here, there are a lot of interesting things about the PNG format developing progress. By the way, thank you for reading my article. There are many image types that I had learn in class such as JPEG, TIFF, GIF, BMP, etc.… Next time, I will talk about histogram of picture and cumulative histogram as well as how to contrast the picture by histogram using mathematics functions and coding”
