Well M31 needs no introduction, I suppose. Being the visually biggest galaxy in the sky and one of the easiest objects in the sky to get a decent first image on it has a special pull, especially for new people joining the hobby. As it did for me. After 5 years in this hobby and 4 years since my last image of it I thought it is time to revisit this classic.
I have learned so much and honed my skills so thoroughly that I was wondering what would be the result of this effort and boy I am proud of it. I especially wanted to work on a new process for augmenting the red channel with nebula information from my Ha filter. I was not satisfied with the "standard" process documented everywhere with a specific Pixelmath formula. The reason is that it always destroys the color balance because the color balancing routines are based off off RGB OR narrowband star information (in Pixinsight) so I always ended up with bland and or slight green tints. The new process I thought of: basically I stretched Ha, removed the stars, unstretched back into linear, deliberately clipped the background to black with a HistogramTransformation and then used Pixelmath with what would be the equivalent of "Screen" in Photoshop. I suppose you could even just use red + ha though. Worked perfectly, PhotometricColorCalbration still works like a charm and you get the "expected" yellow/blue mix of colors in the galaxy. I also like this process more because the nebulae are not that "in your face" but it is a more subtle augmentation. Additionally it does not introduce much noise into the red channels background which is a nice bonus.
In any case, I wanted to produce the best M31 I could imagine and I have to say that I am happy
Enjoy!
I just realized the funny coincidence that I have 31 hours of exposure time for M31, ha!
Comments