HSV colour space for video processing

I want to process a video in HSV colour space. For the saturation values of videos. How can I do the conversion between rgb to hsv videos? I am new on these topics maybe the question is so simple but I really want to do it. I tried to work on frames and also don't know how can I reconstruct a video from processed frames. Could you help me about these topics ?

Answer 1

[Image Analyst]

You can do this

thisFrame = read(videoObject, k); % Get k'th frame.
hsvImage = rgb2hsv(thisFrame);
saturationImage = hsvImage(:, :, 2);

See attached demo where I track a green Sharpie pen using Saturation.