data brushing is extremely slow

Hello everyone

I am using matlab (2016 b) data brush to brush part of data from a picture I2, but it's extremely slow. Please help or give some suggestion. Greatly appreciate it.

I2 is 282 by 282 matrix. It's quite easy to show this figure with imshow(I2), however, matlab built-in brush doesn't work on the figure generated by imshow.

Then I made little change and used scatter to plot this image as the following:

[x,y,z]=find(I2);

scatter(x,y,z)

Now matlab built-in brush works on figure generated by scatter, however, it's extremely slow when brushing data on the figure.

Could someone explain why it's like this? Is there a better way to brush some data from I2?

Thank you very much

Answer 1

[Albert]

Thanks for you comments. I apologize for not posing the right answer here. For my case, there is nothing wrong with MATLAB. Actually I used scatter3. Here is what I did: scatter3(x,y,z,5,v,'s','filled'); we need to specify the size of the marker, in the above case, the size of marker is 5; if we don't designate a fixed size marker then the value v become the size of marker, which will severely slow down the progress. The argument v here is used to indicate the color of the marker.

Hopefully, this would help.

Answer 2

[Bettina Guebeli]

I have the same problem, since the update from version 2014a to version 2016b my function needs about 3x as long as before :-S

any suggestions where this might come from or how to adress the problem?

[Albert]

See my answer posted below. Thank you.