Pixel Selection within a GUI

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Ryan
Ryan on 24 Apr 2013
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.

Accepted Answer

Image Analyst
Image Analyst on 24 Apr 2013
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);

More Answers (1)

Matt Kindig
Matt Kindig on 24 Apr 2013
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).

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