function init(){
                // var time_start = new Date().getTime();
                if(!quality) quality = 50;
                // Create tables
                initCharLookupTable()
                initHuffmanTbl();
                initCategoryNumber();
                initRGBYUVTable();
    
                setQuality(quality);
                // var duration = new Date().getTime() - time_start;
                // console.log('Initialization '+ duration + 'ms');
            }
Detecting vertical squash in loaded image.
Fixes a bug which squash image vertically while drawing into
canvas for some images.