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How can I show where an image was clicked from a scatter3 plot?

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I created a small app using appDesigner:
It allows loading an RGB image and displaying a CIE Lab scatter plot in 3D. I attached a copy of the app.
My question is, once I clicked a point in the scatter plot, how would I be able to show the corresponding pixel on the 2D image?
I guess I have to respond to the click event of the scatter?
Any help is appreciated.
The slider at the bottom only serves to change the markersize interactively.
I'm slowly getting the hang of appDesigner. But I'm missing the ability to browse variables of the "script" environment and a few other goodies.
Is there documentation on appDesigner?

Answers (1)

Image Analyst
Image Analyst on 23 May 2024 at 2:50
Not sure how to get the lab value from your click, but assuming you figure that out, you can get a binary image of all the pixels in the image that are within some small tolerance of that lab value.
labImage = rgb2lab(rgbImage);
[lImage, aImage, bImage] = imsplit(labImage);
tolerance = 0.05; % Whatever you want.
matchL = (lImage > lClick - tolerance) & (lImage < lClick + tolerance);
matchA = (aImage > aClick - tolerance) & (aImage < aClick + tolerance);
matchB = (bImage > bClick - tolerance) & (bImage < bClick + tolerance);
matchingPixels = matchL & matchA & matchB;
overlaidImage = imoverlay(rgbImage, matchingPixels);
imshow(overlaidImage);
Hopefully it's self explanatory. That's just off the top of my head, untested so it may need modification.
  5 Comments
Roger Breton
Roger Breton on 24 May 2024 at 14:07
Looks like I'm wasting my time with datacursormode and appDesigner. Porting this line of code:
> DataCursorMode1 = datacursormode(fig_3D);
to my appDesigner app always results in "Invalid Handle". This is the line of code I try:
> DataCursorMode1 = datacursormode(app.fig_3D);
The app.fig_3D is the name of the axis. The documentation says something about appDesigner and "UIfigure" but there are no examples, nothing to investigate further?
Image Analyst
Image Analyst on 25 May 2024 at 16:10
Sorry, I haven't used the data cursor with App Designer.
But if you're doing
> DataCursorMode1 = datacursormode(app.fig_3D);
from the command window, I'm pretty sure the command window doesn't know about the app structure of your GUI. Only the code within that GUI itself will see app - i. You'll have to click while using your GUI, and if you need some information outside of your GUI you'll have to save it out to disk somehow, though there may be trickier ways to see it all within memory and not saving it to disk.

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