So I downloaded libwebp-0.1.3-windows-x86.zip, there is cwebp.exe inside. I can't figure out how to compress PNGs losslessly into WebP. These are the options

So I downloaded libwebp-0.1.3-windows-x86.zip, there is cwebp.exe inside. I can't figure out how to compress PNGs losslessly into WebP. These are the options it gives: Usage: cwebp [-preset <...>] [options] in_file [-o out_file] If input size (-s) for an image is not specified, it is assumed to be a PNG or JPEG file. Windows builds can take as input any of the files handled by WIC options: -h / -help ............ short help -H / -longhelp ........ long help -q <float> ............. quality factor (0:small..100:big) -preset <string> ....... Preset setting, one of: default, photo, picture, drawing, icon, text -preset must come first, as it overwrites other parameters. -m <int> ............... compression method (0=fast, 6=slowest) -segments <int> ........ number of segments to use (1..4) -size <int> ............ Target size (in bytes) -psnr <float> .......... Target PSNR (in dB. typically: 42) -s <int> <int> ......... Input size (width x height) for YUV -sns <int> ............. Spatial Noise Shaping (0:off, 100:max) -f <int> ............... filter strength (0=off..100) -sharpness <int> ....... filter sharpness (0:most .. 7:least sharp) -strong ................ use strong filter instead of simple. -partition_limit <int> . limit quality to fit the 512k limit on the first partition (0=no degradation ... 100=full) -pass <int> ............ analysis pass number (1..10) -crop <x> <y> <w> <h> .. crop picture with the given rectangle -resize <w> <h> ........ resize picture (after any cropping) -map <int> ............. print map of extra info. -d <file.pgm> .......... dump the compressed output (PGM file). -short ................. condense printed message -quiet ................. don't print anything. -version ............... print version number and exit. -noasm ................. disable all assembly optimizations. -v ..................... verbose, e.g. print encoding/decoding times Experimental Options: -af .................... auto-adjust filter strength. -pre <int> ............. pre-processing filter