How can I plot a heatmap on a custom image?

Hi all,

I have a matrix of size 5x40, which I have been plotting using imagesc. This matrix corresponds to a heatmap of activity in different regions along the hand/forearm(from fingernails to elbow) during an experiment performed. When I use imagesc on this matrix, it understandably plots a grid of size 5x40 with intensities in each grid square corresponding the value within the matrix.

Instead of in a grid form, I would like to plot these data on an image of an actual hand/forearm. Assuming I have an outline corresponding to the hand and forearm, how can I plot the heatmap on this image?

I have been playing around for a while with the image, trying to obtain its coordinates, and reshape the matrix that I have to fit the coordinates of the image, etc but am having difficulty.

Any advice?

Thanks in advance!!

Answer 1

[Image Analyst]

Resize the heatmap to be the same size as the underlying image, then put the heatmap into the overlay:

http://blogs.mathworks.com/steve/2009/02/18/image-overlay-using-transparency/

http://www.mathworks.com/matlabcentral/answers/104889-how-to-overlay-a-foreground-image-over-a-background-image

[Srinivas Chivukula]

Thanks for the prompt reply.

The issue is that the underlying image is of a different shape...

so if I resized the heatmap and overlayed it onto the image, portions of the heatmap would show outside the boundaries of the hand/forearm.

I think I need to reshape the heatmap to the exact size of the outline of the hand/forearm, or somehow segment the hand and forearm and then point a value from my matrix to each segmented region. But I'm not sure how to do this....

[Image Analyst]

Why are they different sizes? And why can't you just resize the heatmap to be the same size as the RGB image? You can use imresize() for that.