How can I change a pixel image from black and white to red & blue

How can I change a pixel image from black and white to red & blue? The image present a letter 'H' with black and white but I want to change the colour into red & blue. ( testmap is my martix name)

    0.2143    0.3395    0.4173    0.3642    0.4025    0.5045
    0.4403    1.0000    0.2445    0.2729    1.0000    0.4498
    0.4804    1.0000    0.2292    0.2102    1.0000    0.4223
    0.3724    1.0000    1.0000    1.0000    1.0000    0.3090
    0.4783    1.0000    0.5504    0.3024    0.5916    0.3535
    0.5192    1.0000    0.2271    0.3599    1.0000    0.4186
    0.3193    0.2616    0.4490    0.2360    0.3270    0.5178
    imshow(testmap(:,:,1), 'InitialMagnification' ,2000);
    
  

Answer 1

[Robert U]

Hi Yik lok Chan,

one way to do so is to utilize colormap()-command:

corn_gray = imread('corn.tif',3);
imshow(corn_gray)

map = [linspace(1,0,256)', zeros(256,1), linspace(0,1,256)'];
figure;
imshow(corn_gray,'Colormap',map)

Kind regards,

Robert

[yanqi liu]

yes，sir，use Robert U method，can get

clc; clear all; close all;
testmap=[0.2143    0.3395    0.4173    0.3642    0.4025    0.5045
    0.4403    1.0000    0.2445    0.2729    1.0000    0.4498
    0.4804    1.0000    0.2292    0.2102    1.0000    0.4223
    0.3724    1.0000    1.0000    1.0000    1.0000    0.3090
    0.4783    1.0000    0.5504    0.3024    0.5916    0.3535
    0.5192    1.0000    0.2271    0.3599    1.0000    0.4186
    0.3193    0.2616    0.4490    0.2360    0.3270    0.5178];
imagesc(testmap(:,:,1));
% red & blue
map=[linspace(1,0,256)', zeros(256,1), linspace(0,1,256)'];
colormap(map); axis equal; axis off;