You can use wcompress from the Wavelet Toolbox and select from among several wavelet compression methods,each with optional parameters.
For three of the supported wavelet compression methods: 'lvl_mmc', 'gbl_mmc_f', and 'gbl_mmc_h', you can specify the compression ration as an input 'comprat'
With all methods you obtain the actual compression ratio as an output argument.
