This image was processed before by the Hubble team but in a totally different way. In their image the hubble palette was used, using 3 images.
For this image 6 different bands were used:
N2: used as yellow
SII: used as red
SIII: used as magenta/red
h-beta: used as lightblue
OIII: used as blue
H-alpha: used as green
The luminance was made from the SII and H-alpha channels.
In this way much more detail in the center can be seen than in the original hubble processing.