I tried searching the forum for "H-II" but gave up looking after the first 30 hits, or so. So, if this topic has already been covered, please point me to the appropriate thread.
With the popularity of OSC cameras has come the advent of dual narrowband filters to make good use of their RGB capabilities for emission nebulae. The H-I+O-III filter would suit generating HOO palette images, and adding a S-II+H-II filter allows one to include SHO palette processing. However, this latter processing would use just the S-II data in the red channel, and completely ignore the very nice imaging resulting from the H-II regions in the G & B channels. So, I am asking: how should/could I use the H-II emission data?, as it would be a waste not to use it, and there is scientific interest in H-II emission regions.
An obvious answer would be to combine the H-II and H-I data into just the red channel. However, it occurs to me (perhaps wrongly) that while H-II emissions are probably generated in the same areas as H-I emissions, the reverse is probably not true. That is, the H-I emission regions are not all energized sufficiently to produce H-II emission, so that the H-II emissions are from specific regions within the H-I emissions, and to my mind, are worth accentuating in some way. What say you, and how should I do this as all 3 channels are already assigned? Would a light red for H-I and a dark red for H-II achieve an acceptable result, and how might I do this?
Paul.
With the popularity of OSC cameras has come the advent of dual narrowband filters to make good use of their RGB capabilities for emission nebulae. The H-I+O-III filter would suit generating HOO palette images, and adding a S-II+H-II filter allows one to include SHO palette processing. However, this latter processing would use just the S-II data in the red channel, and completely ignore the very nice imaging resulting from the H-II regions in the G & B channels. So, I am asking: how should/could I use the H-II emission data?, as it would be a waste not to use it, and there is scientific interest in H-II emission regions.
An obvious answer would be to combine the H-II and H-I data into just the red channel. However, it occurs to me (perhaps wrongly) that while H-II emissions are probably generated in the same areas as H-I emissions, the reverse is probably not true. That is, the H-I emission regions are not all energized sufficiently to produce H-II emission, so that the H-II emissions are from specific regions within the H-I emissions, and to my mind, are worth accentuating in some way. What say you, and how should I do this as all 3 channels are already assigned? Would a light red for H-I and a dark red for H-II achieve an acceptable result, and how might I do this?
Paul.
. Create your own G and B channels by combining the O3 and H2 data. Maybe something for green like O3*0.9 + H2*0.1 and blue something like O3*0.8 + H2*0.2. Fiddle around with the math until you get a result you like. Note, I've never used an H2 filter, so the pixel math formulae I provided are just examples, not any kind of definitive statement of ratios to use in your combination.
