This function presents both bilateral filter and joint-bilateral filter. If you use the same image as image1 and image2, it is the normal bilateral filter; however, if you use different images in image1 and image2, you can use it as a joint-bilateral filter, where the intensity domain (range weight) calculations are performed using image2 and the spatial-domain (space weight) calculations are performed using image1.
Mahmoud Afifi (2019). Joint Bilateral filter (https://www.mathworks.com/matlabcentral/fileexchange/62455-joint-bilateral-filter), MATLAB Central File Exchange. Retrieved .
@Law lingling: No, this is the regular joint Bilateral filter. For fast bilateral filter, you can check this Matlab func https://www.mathworks.com/help/images/ref/imguidedfilter.html
Is this the O(1) JBF？