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Hi Peter,
I don't think that is quite right.
Firstly LCD monitors do not use phosphors - that is used in CRT or Plasma screen per this article:
"So what about the LCD, today’s most obvious alternative to plasma? A liquid-crystal television is, in effect, a sandwich with many ingredients. Its layers include a bright white backlight, a layer of liquid-crystal molecules, a matrix of thin-film transistors, two pieces of polarized glass, and colored filters. The transistors control the voltage applied to the three groups of liquid-crystal molecules that make up each picture element.
When the voltage is on, it twists the molecules, allowing light through the layers of glass and color filters; the molecules untwist when the voltage is off, blocking light. Each picture element consists of liquid-crystal molecules above a red, a green, and a blue filter. Switching the appropriate molecules on and off gives myriad combinations of red, green, and blue light, and therefore the palette of human vision."
Secondly, there is very little data on the internet about this and this surprised me but the few spectrums I could find that showed wavelengths show "red" as a band from 620nm to 780nm. So Ha at 656.281 is not that far from light red. Some posts state red at 650nm others at 680 - so it seems theres not a lot of agreement about what "red" is.
My point was red is a scale, specifically it is 620nm to 780nm in wavelengths.
Photoshop arbitrarily assigns a non defined red to your Ha channel when you use that technique.
My point is to question the correctness of the red Photoshop is assigning to your Ha layer. It may not be right. It may be too red or indeed not dark enough red.
Per that link, given the frailities of what the computer screen displays etc, the 656nm area defintely showed a bit of orangy red which is the colour that images of the Sun are often displayed as.
If you disagree that is fine but it would boil down to disagreeing with the accuracy of the spectrum I linked to rather than theory about monitors and what they can or cannot display in the red band of the visible spectrum.
Deep red is for sure closer to 700nm per any spectrum I have been able to find on the net.
I am sure not all monitors have the same red response. Certainly checking out different laptop monitors showed a huge variance in ability to display different colours from images of my choosing rather than the sales ones.
So basing the red you use based on your monitors performance is a wild variable.
Greg.
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