Extract hands from a video

Hello,

I have a video in which hands perform some gesture and are not always in motion; I have to extract them. Because the first frames are the background I tried with:

readerObj = VideoReader('VideoWithHands.mp4');
nFrames = readerObj.NumberOfFrames;
fr = get(readerObj, 'FrameRate');

writerObj = VideoWriter('Hands.mp4', 'MPEG-4');

set(writerObj, 'FrameRate', fr);

open(writerObj);

bg = read(readerObj, 1);   %background

for k = 1 : nFrames

      frame = read(readerObj, k);

      hands = imabsdiff(frame,bg);

      writeVideo(writerObj,hands);

end

close(writerObj);

but in this way, colors are not "real" and opacity level is low (you can see something through the hands). I wonder whether it would be possible to extract the hands keeping real colors and opacity exploiting the background. Thanks