Internet search leader Google has developed an image format called WebP, which promises to make transfer of images over the web faster by reducing the size of files, a company executive said Thursday.
WebP, which Google is hoping will replace the popular JPEG format, reduces file size by 39 percent on an average, without affecting its quality, said Krishnendu Choudhary, a member of the five-member team that developed the technology.
Since 65 percent of web traffic comprises of images, WebP would make the web faster,” Choudhary, an engineer from Google’s Bangalore centre, told reporters.
WebP uses predictive coding to encode an image, the same methodology used by the VP8 video codec to compress keyframes in videos. Predictive coding uses the values in neighboring blocks of pixels to predict the values in a block, and then encodes only the difference (residual) between the actual values and the prediction.
The residuals typically contain many zero values, which can be compressed much more effectively. The residuals are then transformed, quantized and entropy-coded as usual. WebP also uses variable block sizes
“The degree of compression is adjustable. So, a user can choose the trade-off between file size and image quality,” he added.
WebP is supported by a variety of tools. In addition, it is now enabled in Google Chrome 9, currently in developer channel. Developers have also added support to a variety of image editing tools. This release also provides a lightweight decoder library, libwebp and a command line tool webpconv for converting images to and from the WebP format.
Released a couple of weeks ago, it is an open source project. Three engineers from India were among the five-member developing team, he said.
Joint Photographic Experts Group (JPEG) was a committee formed in 1986 and it created the popular JPEG standard, used to store and send images over the net.