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Thread Subject:
Plotting time

Subject: Plotting time

From: Gavrilo Bozovic

Date: 14 Jul, 2008 08:46:02

Message: 1 of 2

hi!

I have an image processing loop that looks up all the images
in a folder and acquires some data. During the
postprocessing, I display the image, and the points where I
get the data using following commands:

    figure(imdisp)
    image(threshdata*255); %plot a thresholded image
    hold on;
    plot(sat_nr_pos(:,:,2),sat_nr_pos(:,:,1),'wo'); %plot
points where I get some data (21 points)
    plot(temp_nr_pos(:,:,2),temp_nr_pos(:,:,1),'wo'); %idem

I checked the timing, and found that the display of the
image took only 0.02 s, roughly, but the plotting of the
points (42 points in all) takes ten times more.

Does anyone know why it is so, and if it's possible to do it
quicker? I ceased displaying the points, as it takes too
much time, but it would be useful...

Thanks in advance!

Gavrilo

Subject: Plotting time

From: roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson)

Date: 14 Jul, 2008 15:57:06

Message: 2 of 2

In article <g5f3o9$o84$1@fred.mathworks.com>,
Gavrilo Bozovic <gavrilo.bozovic@helbling.ch> wrote:

>I have an image processing loop that looks up all the images
>in a folder and acquires some data. During the
>postprocessing, I display the image, and the points where I
>get the data using following commands:

> figure(imdisp)
> image(threshdata*255); %plot a thresholded image
> hold on;
> plot(sat_nr_pos(:,:,2),sat_nr_pos(:,:,1),'wo'); %plot
>points where I get some data (21 points)
> plot(temp_nr_pos(:,:,2),temp_nr_pos(:,:,1),'wo'); %idem

>I checked the timing, and found that the display of the
>image took only 0.02 s, roughly, but the plotting of the
>points (42 points in all) takes ten times more.

Consider using line() instead of plot().
--
  "Eightly percent of the people in the world are fools and the
  rest of us are in danger of contamination." -- Walter Matthau

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