Simple way to replicate bloom (glow) effect in image using Matlab?
Work in a linear gamma (intensity-linear) color space. Create a Gaussian blurred version of the image. I don't have MATLAB to try it, but it can be done using imgaussfilt. Then add some of the blurred image to the original image, or mix the two images to taste.

Figure 1. Bloom simulated in Gimp by adding to the image its Gaussian blurred copy at 31.5 % opacity.