PGM to PNG converter

.pgm

PGM file format was developed alongside the open-source Netpbm package of graphics program. Developed by Jef Poskanzer in 1988, PGM was a format for storing grayscale images and supporting bitmap. The PGM file format is forward compatible with recent graphics editing software like Corel PaintShop Pro X4, ACDSee Photo Manager 14, and ACD Systems Canvas 15. Being a plain text format, PGM can be edited using any available text editor, and thus survives the quintessential changes that image files undergo when transmitted via email. PGM files come in two types, only differentiated by magic numbers – P2 and P5, which helps graphics editor software identify the data encryption standard.

Portable Gray Map Images can be stored away with each pixel taking up memory space of either 8 or 16 bits. There are two major sections in the plain text string of a PGM file – the header and image data. The header starts with the magic number, followed by characters indicating image width, image height, maximum grayscale shade value – never exceeding 65.536, all sandwiched by whitespaces. Though used mainly on the UNIX-based operating system, being open-source has earned the PGM file compatibility with macOS and Windows.

Jef Poskanzer

.png

Microsoft Paint

PNG – is a scan-line graphic format developed as an alternative to GIF, a commercial license. However, they are both raster image types. PNG is based on the best features of the predecessor, including lossless compression and transparent background support. The PNG technology ensures the preservation of all stages of editing and the restoration of the step by preserving the quality. However, it does not allow us to save several pictures in one file at once, limiting its use in the development of animated images.

The PNG extension was proposed as a tool that helps to transfer and store images on the World Wide Web. The technology is limited to an 8-bit transparency channel so that you can adjust the colors from opaque to transparent. It supports 24-bit RGB colors, matching images, and shades of gray. However, as a non-professional format, PNG can not display other color spaces. Most programs allow you to open such files. They can also run in any browser. Images are different in small weight with good quality.

PNG Development Group (donated to W3C)