Iris Nebula (May 2022) (Paul Macklin)

Iris Nebula (May 2022)

Revision title: Process refinement

Current processing steps (revision D):
Steps in AstroPixelProcessor: The main goal here (besides stacking) is to get a good preliminary stretch, good star colors with somewhat reduced intensity, and minimize light pollution.
+ Stack as normal.
+ Remove light pollution at 30% stretch
+ Stay at 20% bg, 3 sigma, 2.5% base
+ Calibrate star colors as normal
+ Reduce stars with intensity at 85%, size at 90%.
+ Use the built-in sharpening at around 3% to bring out more details for the inner core. Optionally, increasing the HL value may show the central star a little better.
+ Export as tif

Steps in photoshop (round 1): The main goal here is to clean up the colors and contrast, and light curves.
+ Crop and rotate as needed to 6000 x 4000
+ Auto color (with caution--watch for washed out bright details)
+ Adjust levels. Auto is probably okay. It'll typically increase black level to around 20 and choose a gamma of 1.49
+ Adjust curves. Since auto levels already applied a brightening, I typically might use linear contrast here.
+ Adjust hue/saturation in the blue, cyan, and magenta channels by increasing saturation +50 and decreasing brightness -25. This helps bring out colorful details in the center.
+ Optionally reduce yellow saturation -15 to -25 to deal with Tau-Cep

Steps in Topaz: Here we want to reduce noise with a minimalist touch to avoid artifacts.
+ Choose low light.
+ Set Reduce noise to 1%
+ Set Enhance sharpness to 5%
+ Set Recover original detail to 50% to help reduce any sharpening artifacts.
+ All other settings at 0.

Steps in photoshop (round 2):
+ Adjust levels one last time. Keep gamma at 1. Whatever auto suggests as a black clipping, probably cut it in half.
+ Adjust curves once more as needed. Probably linear contrast.
+ Save and export as desired.

Original
B
C
Final
D

B

Title: Increased to 9 hours of data

Uploaded: ...

C

Title: Increased to 11.75 hours, improved processing.

Description: I revised my processing steps a bit in this step, with more refined stretching in AstroPixelProcessor in particular, and better blending in Topaz. More details in the main description.

Uploaded: ...

D

Title: Process refinement

Description: I used some of the built-in sharpening in AstroPixelProcessor to bring out more fine detail in the inner iris.

Uploaded: ...

	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape
Artificial satellite

	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
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Status	Advanced success
Started	...
PixInsight job	BSAA8V5JBBN5TEUMI1HF1SM6VLSNUP2J
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	21h02m02s.25
RA (top/left)	20h46m24s.65
RA (top/right)	21h17m03s.30
RA (bottom/right)	21h19m00s.77
RA (bottom/left)	20h45m37s.79

Dec (center)	+68°10′46″.8
Dec (top/left)	+67°10′57″.6
Dec (top/right)	+67°06′13″.2
Dec (bottom/right)	+69°04′30″.9
Dec (bottom/left)	+69°09′50″.0

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