Question for color set in colorbar

Hello,

I plot an image using imagesc, and the colorbar is automatically set from blue (lowest value, e.g. 0) to red (highest value, e.g. 1). Is there a way to set the interval color from white (lowest value) to red (highest value) ?

Thanks

Answer 1

[Ameer Hamza]

You can also create you custom colormap

White = [1 1 1];
Red = [1 0 0];

t = linspace(0,1,100)';
cmap = Red.*t + White.*(1-t);

colormap(cmap);
colorbar

[aurc89]

Thanks, this is exactly the colorbar I want to obtain! but it gives me error in the code line:

cmap = Red.*t + White.*(1-t);

[Ameer Hamza]

Which release of MATLAB are you using? are you using some version older than 2016b?

[aurc89]

Yes it's 2014a

[Ameer Hamza]

Try this

White = [1 1 1];
Red = [1 0 0];

t = repmat(linspace(0,1,100)', 1, 3);
cmap = repmat(Red,100,1).*t + repmat(White,100,1).*(1-t);

colormap(cmap);
colorbar

[aurc89]

Now it works! Thanks!

[Ameer Hamza]

Glad to be of help.

Answer 2

[darova]

Yes, there is a way. Use colormap

cmap = hot(100);
colormap(cmap(30:end,:))        % i use only last 70 values because first 30 is too dark
colorbar

[aurc89]

Thanks! But this gives the opposite (dark=minimum, white=maximum), what if I want the reversed one (white=minimum, dark=maximum) ?

Answer 3

[Image Analyst]

Try this:

grayImage = imread('cameraman.tif');
white = [1 1 1];
red = [1 0 0];
imagesc(grayImage);
ramp = linspace(0, 1, 256)';
ramp = [ramp, ramp, ramp];
customColorMap = red .* ramp + white .* (1-ramp);
colormap(customColorMap);
colorbar

[aurc89]

I see the image but the code gives error, I think it's due to my previous version of Matlab.

Thanks anyway! I think it works now