pcolor - how to smooth
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Answered: Usenobong Akpan on 15 Mar 2019
I'm plotting some contour map (x, y, z)
If I use Origin, it does some nice smoothing.
In Maltab, using
pcolor(x, y, z); shading interp;
It shows all the noise.
See the picture please.<https://lh6.googleusercontent.com/-fqdFfNo1k5E/UiDzBmXPjtI/AAAAAAAAAz0/iSuJktzidb8/w1044-h352-no/plot.png>
The 3rd plot is a comparison: when data's not noisy, Matlab produces a flat background part (the blue part) too.
I wonder if there's anyway I can get do the same as in Origin using Matlab. Or do I have to smooth the data myself?
Any thoughts are appreciated. Thanks~
Kelly Kearney on 30 Aug 2013
Pretty sure it's just a colormap difference, with origin setting everything less than -90 to black. Try this:
set(gca, 'clim', [-90 -32]);
colormap([0 0 0; jet]);
You'll probably have to fiddle a bit more with the colormap and color limits to get the exact same thing, but that should be close.
Can you somehow get an image out of that? Because images are a lot easier to smoother than a list of random coordinates.
Edited: Image Analyst on 30 Aug 2013
One way, though not necessarily the best way is to just use convolution to blur each color channel one at a time:
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
windowSize = 7;
kernel = ones(windowSize) / windowSize ^ 2;
% Blur the individual color channels.
smoothedPictureR = conv2(double(redChannel), kernel, 'same');
smoothedPictureG = conv2(double(greenChannel), kernel, 'same');
smoothedPictureB = conv2(double(blueChannel), kernel, 'same');
% Recombine separate color channels into a single, true color RGB image.
smoothrgbImage = uint8(cat(3, smoothedPictureR , smoothedPictureG, smoothedPictureB));
Usenobong Akpan on 15 Mar 2019
Please I am a new user of matlab. i need help on the matlab code that would make me plot a single 3 axes graph. I am comparing power (W) and temp (degree celsius) over same time interval. I can if there were of the same unit i.e. W and W over same time interval; but here I am having difficulty.
pls can anyone help out?
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