Pixel Selection within a GUI

Okay soi have four small pictures within a GUI, i need the user select a single pixel from one of these four images. How would i go about selecting a pixel and getting the RGB value from that pixel. When i use impixel() it doesnt terminate after one click, is there a way to make it terminate after the user clicks once? I also keep getting NaN NaN NaN as the values when i use impixel() any idea why that would be happening? I would add code but its a GUI and there is just way too much to post here.

Answer 1

[Image Analyst]

Like I said in your duplicate question you should be able to get the RGB values once you have the row and column from ginput as

rgbTriplet = rgbImage(row, column, :);

or

rgbTriplet = impixel(rgbImage, column, row);

Answer 2

[Matt Kindig]

Easiest (although not particularly clean) way might be to use ginput(), and then round the return coordinates to select the pixel:

[x,y]=ginput(1);
pixel_x=round(x); 
pixel_y= round(y);
pixel_val = img(pixel_x, pixel_y);

For a more "professional" look, you can set a ButtonDownFcn callback when the user clicks the image, and retrieve the 'CurrentPoint' property of the axes (which is set when the user clicks the underlying axes).