This is my third time imaging M33. Each time it has been with a different telescope and each time I've processed it differently. I was amazed at the amount of detail the CDK 14 resolved in the galaxy and this may be the most success I've had with combining hydrogen alpha with broadband. It's also an image that seemed to force me to revisit many of the "standard" techniques I had been applying to my images. It was one of those times when everything I seemed to know was suddenly wrong and it forced me to a better, if not understanding of the tools then at least a better comprehension that I need to pay more attention to the subtleties (and sometimes not so subtle) effects they have on my images. I'll write more that at the end.

Processing:

L:
DBE
BXT
GHS
NXT
HDRMT
LHE

RGB:
channel combination
DBE
BXT
SPCC
GHS
LRGB Combination (adding in L)
Curves (contrast)
SXT (extracting unscreened stars)
Curves (color)
pixel math in stars (screen)
MLT (mild sharpening)

stars:
produce star was of the medium-large stars (I didn't want any of the small stars nor the largest stars)
MT dilate the mask a bit
HT (to lower the levels on those medium stars)

In the last year or so I had grown accustomed to stretching the stars separately and adding them back in at the very end. But, in this image, SXT was removing far too much content in the center of the galaxy. In addition that galaxy was full of small, faint stars that I wanted there.If I stretched the stars they way I normally would then they wouldn't show up. Overall this image required a much gentler setting on both BXT and NXT. Using the PSF from Render PSF caused the core of the galaxy that was full of high spatial frequency data to turn into a wormy mess so I had to use both a much lower PSF value and a much lower amount to get a good result. Similarly, I had to use a much lower amount on NXT to retain all that faint detail in the center. Overall, this image seemed to take everything I thought I knew about the *XT tools and tell me it was wrong. Not wrong in general, but definitely wrong for this image and likely others with similar characteristics. Now that I'm aware of this I need to go back and look at some older data to see if I've messed it up in there the way I almost did here.