H-alpha imaging of galaxies is still rarely practised by amateurs....still isn't fashionable. Very interesting in your image to see the distribution of HII regions so very clearly.
For comparison, I attach an Ha image from the SINGS survey:
Note that the orange channel displays the light from the H-alpha
line only (essentially only one wavelength of light).
The red stellar continuum light from the raw Ha image has been subtracted out, leaving
only nebular light.
The blue channel actually displays broadband
red light from the target object.( technically, it displays the red light of the stellar continuum)