MATLAB: Could I set the colorbar resolution？

pcolor; colorbar

when I plot a large picture using the PCOLOR function, there are many values in one color what makes my pic look like a contour map.

could I set the colorbar resolution to make my picture more smooth?

Best Answer

Give a number close to 256, but not more, to your colormap

image(yourImage);  % I would not use pcolor in most situations.
colorMap = jet(256);
colormap(colorMap);   % Apply the colormap
colorbar;   % Show a colorbar "legend"

Any reason why you're using pcolor? Maybe you don't want the last row and column of your image displayed for some strange reason??? Try imshow() or image() instead.

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MATLAB: Rescale colormap/colorbar with negative value

Change the limits of color axis

caxis([-80 -40])

Bonus: To remove the lines in pcolor, call it like this

p = pcolor(XGrid,YGrid,C)
p.EdgeColor = 'none'

MATLAB: How use two different colormaps for image and pcolor in same figure

Instead of using pcolor() on your data, use

FirstRGBData = ind2rgb( im2uint8( mat2grey(FirstData) ), cm1 );
cm2 = parula(256);   %make sure you use the 256 color version
SecondRGBData = ind2rgb( im2uint8( mat2grey(FirstData) ), cm2 );

Now you can display FirstRGBData and SecondRGBData as images.

The best way to display the two as images depends upon whether you want the two to be in different axes, or if you want the two to have exactly the same size, or if you want the second to overlay part of the first. You should have a look at the XData and YData parameters of image() for information on how to indicate which portion of the axes to display the image at.

I suspect that you want the second one to be at least partly transparent. You would pass AlphaData to image() to do that. For example,

image(FirstRGBData, 'XData', [1/2 4000+1/2], 'YData', [1/2 4000+1/2]);
hold on
image(SecondRGBData, 'XData',  [1/2 4000+1/2], 'YData', [1/2 4000+1/2], 'AlphaData', 0.5);

Best Answer

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MATLAB: Rescale colormap/colorbar with negative value

MATLAB: How use two different colormaps for image and pcolor in same figure

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