Starting with GDAL 1.9.0, GDAL can read and write WebP images through the WebP library.
WebP is a new image format that provides lossy compression for photographic images. A WebP file consists of VP8 image data, and a container based on RIFF.
The driver rely on the Open Source WebP library (BSD licenced). The WebP library (at least in its version 0.1) only offers compression and decompression of whole images, so RAM might be a limitation when dealing with big images (which are limited to 16383x16383 pixels).
The WEBP driver supports 3 bands (RGB) images. It also supports 4 bands (RGBA) starting with GDAL 1.10 and libwebp 0.1.4.
The WEBP driver can be used as the internal format used by the Rasterlite driver.
Starting with GDAL 1.10, XMP metadata can be extracted from the file, and will be stored as XML raw content in the xml:XMP metadata domain.
QUALITY=n: By default the quality flag is set to 75, but this option can be used to select other values. Values must be in the range 1-100. Low values result in higher compression ratios, but poorer image quality.
LOSSLESS=True/False (GDAL >= 1.10 and libwebp >= 0.1.4): By default, lossy compression is used. If set to True, lossless compression will be used.