Wanting to learn how to implement pixel math - Forums

Topic starter

Nov 1, 2024

I am looking for a good resource to learn pixel math (PM). I use Siril for processing and I've tried using PM with a little success. I just can't figure out what formulas to use to achieve various looks.
this image was done with the following formula, saw it used on a tutorial from Deep Spae Astro.
Shot with a L Extreme filter

R Ha
G .4*OIII + .6*Ha
B OIII

The Elephant Trunk nebula sh2-131

For background,
Siril
OSC camera
L-extreme and SII filters are being used

Taman

Nov 1, 2024

Here are a few useful expressions that I've collected from various sources, they all work with Siril:

Narrowband Luminance = (Ha^2 + Oiii^2 + Sii^2)/(Ha + Oiii + Sii)

RGB Luminance = (R^2 + G^2 + B^2)/(R + G + B)

====================================

SHO Foraxx Palette

R = (Oiii^~Oiii)*Sii + ~(Oiii^~Oiii)*Ha
G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + ~((Oiii*Ha)^~(Oiii*Ha))*Oiii
B = Oiii

====================================

HOO Foraxx Palette

R = Ha
G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + ~((Oiii*Ha)^~(Oiii*Ha))*Oiii
B = Oiii

https://thecoldestnights.com/2020/06/pixinsight-dynamic-narrowband-combinations-with-pixelmath/

====================================

Synthetic RGB from Narrowband

R = 0.5*Ha + 0.5*Sii
G = 0.5*Oiii + 0.094*Ha
B = 0.295*Oiii + 0.1*Ha

https://www.cloudynights.com/topic/661929-a-fresh-take-on-synthetic-rgb-from-narrowband/

===================================

Extract Ha & Oiii from Optolong L-eXtreme

Ha = R
Oiii = (2*G+B)/3

==================================

Ha Continuum Subtraction

Ha - f * (R- med(R))

f = 0.13 approx

Helpful Concise

TiffsAndAstro

Nov 1, 2024

Keith Belzner:
I am looking for a good resource to learn pixel math (PM). I use Siril for processing and I've tried using PM with a little success. I just can't figure out what formulas to use to achieve various looks.
this image was done with the following formula, saw it used on a tutorial from Deep Spae Astro.
Shot with a L Extreme filter

R Ha
G .4*OIII + .6*Ha
B OIII

The Elephant Trunk nebula sh2-131

For background,
Siril
OSC camera
L-extreme and SII filters are being used

Looks good from here.

Tony Gondola

Frequent contributor

Nov 1, 2024

It looks like you're already getting the hang of it! Taman gave you a lot of useful combinations. After that it's a matter of small adjustments depending on your data and the look you want. I'm sure pixel math is capable of a lot more so don't be afraid to experiment.

Well Written Respectful Supportive

Keith Belzner

Topic starter

Nov 1, 2024

Here are a few useful expressions that I've collected from various sources, they all work with Siril:

Narrowband Luminance = (Ha^2 + Oiii^2 + Sii^2)/(Ha + Oiii + Sii)

RGB Luminance = (R^2 + G^2 + B^2)/(R + G + B)

====================================

SHO Foraxx Palette

R = (Oiii^~Oiii)*Sii + ~(Oiii^~Oiii)*Ha
G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + ~((Oiii*Ha)^~(Oiii*Ha))*Oiii
B = Oiii

====================================

HOO Foraxx Palette

R = Ha
G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + ~((Oiii*Ha)^~(Oiii*Ha))*Oiii
B = Oiii

https://thecoldestnights.com/2020/06/pixinsight-dynamic-narrowband-combinations-with-pixelmath/

====================================

Synthetic RGB from Narrowband

R = 0.5*Ha + 0.5*Sii
G = 0.5*Oiii + 0.094*Ha
B = 0.295*Oiii + 0.1*Ha

https://www.cloudynights.com/topic/661929-a-fresh-take-on-synthetic-rgb-from-narrowband/

===================================

Extract Ha & Oiii from Optolong L-eXtreme

Ha = R
Oiii = (2*G+B)/3

==================================

Ha Continuum Subtraction

Ha - f * (R- med(R))

f = 0.13 approx

Thank you, I looked at the link under the HOO formula and it was helpful. I'm still looking for information that explains in a more basic way. Formulas are great to plug in but I want to understand the how's and why of it.
again very helpful