Painting using a projector and Photoshop

Hello Everyone!
Thank you for having me on this site. I would love some pointers in how to use photoshop to create large canvas paintings from photographs. I have a projector.
In short I would like to be able to break the image I'm using down to, say, 20 - 30 colours. Then, 1 by 1 i would like to be able to project each colour onto my canvas, trace round it and colour it in.
I have not been able to find any tutorials online. Any help will be hugely appreciated. Thank you
I am fairly new to PS. I have CS3

hi

the way to reduce colours in photoshop is to change your image mode to indexed color, selecting the number of colours you require; always work on a copy, not the original image

however I would then project that image onto the canvas and draw outlines over it and then colour these in using a printed image for reference

the way you suggest is unlikely to work unless the image is coloured only with flat pure tones, and even then I see no advantage in it

but of couse, without seeing exactly what it is you are working with and what you wish to achieve, I can only speak from my own experience and I have not used projectors for art in a long long while ;)

youtube has tons of videos on the use of projectors in art...