How do I get texture feature images from GLCM texture analysis?
Looking at these references, this is what I would understand:


The Haralick descriptors only create a single value for each GLCM (as you also thought).
The Rampun paper creates 32 images, describing 32 different features for each input image.
The crucial point is this sentence: On the other hand, we used
a small window size of 5 x 5 throughout the process
This sentence, in combination with this one (taken from here, p.25, Sec. 2.6): The GLCM Texture Image is the result of moving the GLCM window across the entire image or sub-image. 


So, my understanding is:


Create moving window of size 5x5
move this window over your input image
for each window position (x,y), calculate a feature (e.g. contrast), and write the value for this feature into the "contrast" image at position (x,y).


This way, you extract "local" features, i.e. the GLCM is only done over local area of size 5x5. This also makes more sence, since the Rampun paper wants to segment images, i.e. it needs local features instead of global ones.