CODEWITHSUNDEEP
matlab
Jam1
Jam1

Reputation: 649

Give certain values specific color in matrix with imagesc

Lets say I have a matrix A

A = [1 1 1 1 1 1 1; 
     1 0 0 1 0 0 1;
     1 0 0 0 0 1 1;
     1 0 1 0 1 0 0;
     1 0 0 0 0 0 1;
     1 1 1 1 1 1 1];

And I want to give the 1's at the edges a specific color, and the 1's that are not at the boundaries a specific color and the 0's a specific color, How do I go about this?

Currently I just have imagesc(A), I have been reading up on colormap and I do not understand it. To me it seems they just have set color scheme. On the website I see winter, summer, hot, jet etc. I would like to know how to modify, and how and where colors are displayed, and what colors are to be displayed.

Upvotes: 0

Views: 134

Answers (1)

itzik Ben Shabat
itzik Ben Shabat

Reputation: 927

Colormap in matlab allows you to set a color for an indexed image (in your case you only have 2 indexes - 0,1 which is usually interperted as black and white). MATLAB has some predefine settings as you mentioned winter,summer, hot, jet etc.

You can define your own colormaps.In order to do that you need to first build a matrix of nX3 where n is the number of colors you need and the 3 is attributed to the RGB color space.

In your example above 

imagesc(A)

Gives a blue and yellow image (since the default is parula).

If you define the new colormap matrix as follows 

Cmap = [1 1 1; 0 0 0];
colormap(Cmap);

You will get the image in black and white (because of the values in Cmap). You can change the Cmap matrix values for different colors.

Upvotes: 3

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