[RCC] How to find the right colors and tone in a LHaRGB image - Forums

Topic starter

May 13, 2021

I always confuse with what is the correct colors and tone in LRGB/LHaRGB images. The image of Lagoon & Trifid nebulae that I recently shot is an example: I am not sure if the darkness on the right side of the image is correct or just a gradient.

Gear and acquisition: QHY294M, WO RedCat, Optolong filters Ha 9*300s L40*60s RGB ~ 20*60s each

Workflow:
Pre-processing and integrate in APP
Combine HaRGB remove gradient (L & HaRGB) and color calibration in APP export fit files (one Chrominance and one Lum files) to PI
Deconvolution Luminance
Linear Denoise Chrominance and Luminance, stretch to non-linear (using EZ processing suite in PI)
LRGB combine, export 32bit tiff to Lightroom for tone and color adjustments

Lagoon Nebula & Trifid Nebula

Clear skies,
Kijja

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Peter Robertson

Jan 6, 2022

There are many others better qualified to answer and I don’t use PI ( yet) but it looks like a very nice image, congratulations. You can compare with my own effort here https://www.astrobin.com/jr379u/

I didn’t get much-blue in triffid with my set up and location, but happy with the overall image.

Clearly a number of factors (but especially light pollution) can cause the image to darken on one side. The colours in your image look great, but I also wonder if the salmon pink is the right shade?

I use a one shot colour camera modified and try to keep close to the color I obtain with that when adding a luminance layer. In PS the L layer will lighten the reds to pink unless you counter that by darkening the red and boosting saturation a little.. But I have also seen experts saying that pink is the “right” color . So interesting question, hopefully someone else has the answers.

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Georg N. Nyman

Jan 6, 2022

I think, your colors are fine - maybe slightly different from what one is used to get normally with narrow band filters (..pink as example) but overall, you have done a very good job.

And regarding the "right" colors - I am convinced that there are no "right" colors because we cannot see most of the celestial targets with our own eyes - yes, some are larger, like M31 or M42, but if you look through a telescope, the colors are rather weaker compared to most photographs here on Astrobin. Hydrogen and Oxygen - red and blueish on photographs, their emission is for our eyes not too strong and if you look at the Hubble pictures, the colors are different at all. Not taken with LRGB but with the Hubble HSO or HOS primarily.

On top of that all, colors are subjective - living creatures see colors different - so do people. Some see more blue, some more red, some more green, women see more UV than man etc ( thats why buying shoes with women is usually very demaning for men….brown is not brown for them :-) )

As long as one does not overdo the saturation, colors of different tint are fine - for me at least, and what I write, is just my personal opinion.

Keep doing what you are doing, it is very fine and others, who may sound critical, should provide a significantly better color rendition if the wish…. Overall, you image is very fine.

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andrea tasselli

Frequent contributor

Jan 6, 2022

The gradient you see is correct as to the lower left there is the Sagittarius Star Cloud and to the upper right the MW is tapering off. This said the colours are a bit skewed and there is too much green in the stars/background. Your M8 is a bit too pinkish for my taste but this is maybe a matter of preferences. Use PCC in PI to try and get the right stars colour

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KIJJA JEARWATTANAKANOK

Topic starter

Jan 8, 2022

Peter Robertson:
There are many others better qualified to answer and I don’t use PI ( yet) but it looks like a very nice image, congratulations. You can compare with my own effort here https://www.astrobin.com/jr379u/

I didn’t get much-blue in triffid with my set up and location, but happy with the overall image.

Clearly a number of factors (but especially light pollution) can cause the image to darken on one side. The colours in your image look great, but I also wonder if the salmon pink is the right shade?

I use a one shot colour camera modified and try to keep close to the color I obtain with that when adding a luminance layer. In PS the L layer will lighten the reds to pink unless you counter that by darkening the red and boosting saturation a little.. But I have also seen experts saying that pink is the “right” color . So interesting question, hopefully someone else has the answers.

@Peter Robertson Thank you for sharing your thoughts. Sometimes too many processing choices lead to completely different final images. Adding L is a good idea to start.

Kijja

KIJJA JEARWATTANAKANOK

Topic starter

Jan 8, 2022

Georg N. Nyman:
I think, your colors are fine - maybe slightly different from what one is used to get normally with narrow band filters (..pink as example) but overall, you have done a very good job.

And regarding the "right" colors - I am convinced that there are no "right" colors because we cannot see most of the celestial targets with our own eyes - yes, some are larger, like M31 or M42, but if you look through a telescope, the colors are rather weaker compared to most photographs here on Astrobin. Hydrogen and Oxygen - red and blueish on photographs, their emission is for our eyes not too strong and if you look at the Hubble pictures, the colors are different at all. Not taken with LRGB but with the Hubble HSO or HOS primarily.

On top of that all, colors are subjective - living creatures see colors different - so do people. Some see more blue, some more red, some more green, women see more UV than man etc ( thats why buying shoes with women is usually very demaning for men....brown is not brown for them :-) )

As long as one does not overdo the saturation, colors of different tint are fine - for me at least, and what I write, is just my personal opinion.

Keep doing what you are doing, it is very fine and others, who may sound critical, should provide a significantly better color rendition if the wish.... Overall, you image is very fine.

@Georg N. Nyman Thank you for your answer. Love your metaphor on colors perception of women, I've spent my life with a living evidence here for years.

KIJJA JEARWATTANAKANOK

Topic starter

Jan 8, 2022

andrea tasselli:
The gradient you see is correct as to the lower left there is the Sagittarius Star Cloud and to the upper right the MW is tapering off. This said the colours are a bit skewed and there is too much green in the stars/background. Your M8 is a bit too pinkish for my taste but this is maybe a matter of preferences. Use PCC in PI to try and get the right stars colour

@andrea tasselli Oh, I see. It appears that Star color calibration in APP skews towards blue-green even I redo color calibration with PCC to image files that processed and calibrated from APP. Thank you very much.

Kijja