WebP is an open-source format for image files, raster images. Created in 2010 by Google for web graphics in order to quickly upload images to web pages. This is the main advantage of WebP files. Compression of images in this format can go with or without loss, depending on what level of quality you want to achieve. Thus, lossless compression is 26% better than in PNG files. If quality loss is acceptable, then compression in WebP format is 25-34% better than in JPEG files. Full support for WebP is not yet available on Firefox, Internet Explorer, and Safari.
PNM is a raster image category format. This is a bitmap bitmap created in Portable Any Map format. As you know, this format was intended from the very beginning to process some types of portable monochrome black and white images (PBM), color images (PPM) and grayscale images with shades of gray (PGM). Allows the inclusion of raster graphics data in the .PBM, .PGM or .PPM format. Such formats can provide an intermediate representation of data during the conversion of raster graphic files by different platforms. Separate applications support these three formats directly because they are defined as the PNM format. Able to be stored using binary data or ASCII text. PNM is the common format for the Netpbm package. It contains intermediate files that are used when it comes to converting several open source programs called Portable Bitmap. The PPM format was developed by J. Poskanzer. This is the easiest format for storing graphics. PNM files store one image. They do not apply compression. To view and process a bitmap image in PNM format, you can use programs such as GIMP, ImageMagick, Newera Graphics Converter Pro, XnViewMP. The same programs are able to convert images of this format.