Changing Color of an area within a picture, webtechnique

Software fully runs with Webtechnlogy, target are mobile devices. Software should be able to handle a foto, which means, loading it on the screen. User should be able to select a certain area by touching it. all pixel with same colour next to this should be selected. see photoshop magic stick function. User should be able to change color of the selected area. also by touching and getting color from color picker. saving pic must be possible.