How do you mark and extract an area from an imagesc-figure?

Hi guys,

I'm looking for a tool that works in a similar way to Matlab's brush tool.

I graph a spectrogram of a signal, i.e. a 2D array, using imagesc. In this spectrogram I would like to manually mark a certain area and extract the data within this area. For this purpose I tried to use Matlab's brush tool. But obviously it doesn't work for imagesc-figures. Can you help me and suggest solutions? Is there another tool from Matlab that works for imagesc-figures?

Thanks for your help.

Answer 1

[Adam Danz]

"I would like to manually mark a certain area and extract the data within this area."

There's a few things you could do. Check out

• ginput

Requiring Image Processing Toolbox:

• drawfreehand | freehand
• drawcircle
• drawassisted | drawcrosshair | drawcuboid | drawellipse | drawline | drawpoint | drawpolygon | drawpolyline | drawrectangle

See ROI creation overview for details.

You can use these tool to select a region and return the coordinates of your selection. Then you can use those coordinates to isolate a section of your data.

[Frederik Schmidt]

Thanks for your help.

The function drawrectangle is the one I've needed.

Answer 2

[Image Analyst]

See my attached masking demo.

[Frederik Schmidt]

Thanks for your help, too.

The trick with the binaryImage is a good one.