New Script: DBXtract

Carmelo Garcia de Rich:

Hi Raúl, in which sensors?

Congrats for this usefull script.

Enol Matilla:
I see one problem, but this problem is inevitable using an OSC.
Any time you add or substract the splitted RGB channels to get the narrowband compositions, you are mixing the bands, because one channel didn't have only one band. May be a despreciable amount, but testing with bright objects as M27, and comparing a real OIII image with a syntetic one (generated doing the inverse of the Youtube formulas and then the script) you can see some differences.

But like I said at the beginning, this is inevitable using an OSC with multi band filters (with single band filters you simply extract luminance).
This aproach (the script) gives better results than using only single extracted channels.

Greetings.

Raúl Hussein:
Dual Band eXtract
The script allows you to extract the SII, HA and OIII signal from dual band filters to compose a SHO image



Download script: https://dbxtract.astrocitas.com/
Youtube video (spanish version): https://youtu.be/hREbb3tIztw?si=4iwh79why6RylUu3

In color cameras, it's increasingly popular to use dual-band filters like the well-known Optolong L-Ultimate and Askar ColorMagic. However, extracting the specific signal from each emission band can be challenging.

This script enables the extraction of the emission bands of Ha, SII, and OIII, taking into account the contributions of each band in the RGB channels. This is done by considering the quantum efficiency (QE) parameters of different Sony sensors (IMX). Inspired in Dark Sky Geek youtube channel (thanks)

For example, the following graph represents the QE of the IMX 571 sensor. By drawing a line for each of the emission bands captured by the most common dual-band filters, we obtain that each RGB channel is represented by a percentage of transmission. Therefore, it is not correct to assign the Ha or SII signal natively to the R channel, nor the OIII to the G or B channels.

From these formulas, it's possible to isolate each of the Ha, SII, and OIII signals as part of an RGB combination. For example, HA = (R - 0,03*O3) / 0,80 or S2 = (R - 0,03*O3) / 0,73 to IMX 533 sensor.


Finally, the OIII signal should be calculated after isolating Ha and SII in their respective B and R channels using this formulas:


An example of Askar ColorMagic C1 and C2, ZWO ASI 533mc-pro of NGC 7635NGC 7635, Bubble Nebula by Fran Masip

Figure 1. HO and SO images


Figure 2. SII, OIII and Ha extracted signal


Figure 3. SHO combination


Figure 4. Final image


Download script: https://dbxtract.astrocitas.com/
Youtube video (spanish version): https://youtu.be/hREbb3tIztw?si=4iwh79why6RylUu3

Alejandro Navarro:
Gran trabajo como siempre Raúl. 
Ya lo estuve probando y es evidente la mejora. 
Un abrazo

Wow, this is great.

Would this work with a tri or quadband filter?  I have a Radian Ultra quadband that gets very little use these days.

Kay Ogetay:
Great work Raúl! Three parameters and three equations, linear algebra at its best Would you consider adding an option to manually enter the coefficients? In that way, I think people can find their best coefficients from the ones that automatically comes with the sensor info.