Assigning color to gray image

I have a gray image (it's a flame) like the image below and I want to get something like the next image. I think I need to apply color and contour maps. But I don't know how to apply them. Thank you.

Answer 1

[Image Analyst]

I'd just use colormap and not mess with contours unless you know what you're doing and what you want. To pseudocolor a grayscale image an leave it as grayscale but display it as colored:

imshow(grayImage);
colormap(jet(256));
colorbar;

To convert a grayscale image into a true color RGB image and display the RGB image instead of the pseudocolored image:

rgbImage = ind2rgb(grayImage, jet(256));
imshow(rgbImage);

You don't use color bars with RGB images.

[Karina]

Thank you. That was the answer I was looking for.

Answer 2

[Walter Roberson]

contourf(YourImageMatrix);
colormap(hot)

[Karina]

Thank you.