how to perform false coloring without gray scale conversion?

Answer 1

[Image Analyst]

This is done by the function rgb2ind(). You can make up whatever colormap you want.

indexedImage = rgb2ind(rgbImage, myColorMap);

If you want to see your image as an RGB image again, looking posterized/pseudocolored if your colormap doesn't have too many rows in it:

rgbPosterizedImage = ind2rgb(indexedImage, myColorMap);

Or you can display it as an indexed image with the colormap:

imshow(indexedImage);
colormap(myColorMap);
colorbar;

[sruthi viswanath]

Thank you very much

[sruthi viswanath]

Can you please suggest some color palette that gives best result when reverse false coloring is performed

Answer 2

[KALYAN ACHARJYA]

More clarification needed, though I am trying to figure out what you looking for. %You can directly force the particular value in the respective color plane. %Say if you want all pixel values less than 124 then you can be forced all pixel values should be red color in any plane

rgb_image=imread('test.jpg');
figure, imshow(rgb_image);

R=rgb_image(:,:,1);
G=rgb_image(:,:,2);
B=rgb_image(:,:,3);
R=R<=124;
G=G>124; 
G=G<230;
B=B>230; 

And cat displays all three planes. Also, you can force any specific two colors to zero, the third one will remain. 

G(:,:)>124==0; 
B(:,:)>124==0;

[sruthi viswanath]

Thank you!!

I want to perform false coloring without color-to-gray conversion.For each color value I(x, y) in the original image, the corresponding false color value FI(x, y) need to compute

FI(x, y) = Pc [I(x, y)]

where Pc denotes the cth channel of the color palette P.