Understanding the Google's WebP image format

WebP (Web Performance) is an brand new Image format developed by Google. Google purchased the technologies used in WebP format from On2Technologies. It's one of those projects of Google which aims for making the web faster. 

WebP image format comes with both Lossy and Lossless compression for images on web. When lossless compared with the PNG images WebP format gains an upperhand as it's size is found to be reduced by 25% and when compared with JPEG format it's 25%-34% smaller in size than traditional JPEG. WebP supports lossless and lossy transparency. 

WebP uses an predictive coding to encode an image. In the predictive coding methodology the current value of the neighbouring pixel is used to predict the value in the block to be coloured next. And then after this, Actual Values of neighbouring pixels - Predicted values for the current block is calculated, and the residue which is left is encoded. 

The residue obtained can be compressed easily due to the fact that it has many zero's in it. A WebP file consists of VP8 or VP8L image data, and a container based on RIFF. The standalone libwebp library serves as a reference implementation for the WebP specification and is available at this git repository and as a tarball. 


Source- https://developers.google.com/speed/webp/?csw=1


A quick comparison between the JPEG and WebP image formats - 

Topic                                         JPEG                                         WebP
-------------------------------------------------------------------------------------------------------
Lossless Compression                  NO                                            YES

Lossy Compression                      YES                                           YES

RGB Colorspace                          YES                                           YES

Gray Scale Colorspace
(black and white)                          YES                                           YES

Alpha Channel
(Transparency)                             NO                                             YES

Supporting Applications                Universal(almost)                        Limited
                                                                                  (Google Chrome, Android, Opera, G-mail,                                                                                       Picasa, ImageMagik, GDAL and many                                                                                                        other support using plug-in)