This paper presents a novel method of lossy image compression for digital colorful image sensors with Bayer color filter arrays(CFAs)based on an analysis of existing compression-first methods.An improved compression and decompression structure is described.The captured CFA raw data are firstly Iowpass filtered in RGB space by a smooth filter followed by a down-sampling operation.Next,the data are transformed from RGB space to YCbCr space. Lastly, the filtered data in YCbCr space are compressed directly before full color interpolation to avoid redundancy. The presented method can provide a lower compression ratio and has lower complexity than both conventional interpolation-first image compression methods and other similar existing compression-first methods.