vue-advanced-cropper image croped sized is bigger than the original

I'm implementing a system where user choose image, he must crop it before save; i'm using vue-advance-cropper plugin; all system is setted up but the result image sized is bigger than the original;

example: i insert image at 307ko i got 448ko; i insert image at 40ko i got 206ko;

is there any option that i missed to make the result lesser size than the original or is there not anything can be done?