Andromeda galaxy - taken with a Canon T7i at ISO 800 on an Omegon Minitrack lx2, Asahi Takumar 135mm f2.5 at f4 lens. 50 frames of 60s, no flats. Processed in Pixinsight, details to follow :)

1 stack of 50 images, Canon 800D at ISO 800, Asahi Takumar 135mm f2.5 lens at f4.0, 1m exposures, Omegon Lx2 tracking mount. 45 darks, 120 biases. Processed in PixInsight as below

***** Integration
lightvortexastronomy tutorial (www.lightvortexastronomy.com/tutorial-pre-processing-cali...)

* CC defect list + master dark
* weighing: (15*(1-(FWHM-FWHMMin)/(FWHMMax-FWHMMin)) + 15*(1-(Eccentricity-EccentricityMin)/(EccentricityMax-EccentricityMin)) + 20*(SNRWeight-SNRWeightMin)/(SNRWeightMax-SNRWeightMin))+50
* img 1507 ref

*****Linear processing

*** Crop

*** DBE, 1.5 tolerance

*** Star mask creation
* star_mask_large: large scale structure 2, small scale 1, noise threshold 0.1, scale 6, binarize
* star_mask_small: noise 0.15, scale 4, small scale 3 comp 1, smoothness 8, binarize, midtones = 0.02
* star_mask_all - sum of star masks

*** Color calibration
* SNCR 0.5 on green, preserve lightness
* apply a trous wavelet transform to star mask all, keep residual of 4 (blurred_star_mask)
* invert image
* apply SNCR 0.9 on green, preserve lightness
* remove mask
* invert image again
* Background neutralization
* Color calibration w/background and structure detection

*** Deconvolution
* Created range mask - extracted luma, applied standard STF, then histogram shadow = 0.2 mids = 0.25 high = 1 and a trous wavelet transform keeping residual of 4
* Deconvolve with range mask on, 100 interations, luminance, custom PSF, dark 0.025 bright 0.004, local deringing with star_mask_large, wavelet regularization

*** Star reduction
* Apply, erosion operator w/star mask small, 4 iterations 0.15

*** Linear noise reduction
jonrista.com/the-astrophotographers-guide/pixinsights/eff...

*TGV - small noise
Created TGV masks - extracted luminosity, standard stretch (tgv_luma_mask), curved it with black point at ~0.2 and white at ~0.5, moved histogram point to middle (tgv_mask)
apply tgv mask inverted to the image, give luma mask as local support
TGV chroma str 7 edge protection 2E-4 smoothness 2 iterations 500
TGV luma str 5 edge protection 1E-5 smoothness 2 iterations 500

*MMT - larger noise and TGV artifacts
Created MMT mask - extract luminosity, standard stretch, move histogram point to 75%, apply low range -0.5. Apply inverted
MMT mask - 8 layers, threshold 10 10 7 5 5 2.5 2 2 on rgb

*****Nonlinear

***Initial stretch
* extract luminance, autostretch, apply to hist - luminance channel
* Apply masked stretch to main image, 100 iterations, HSV Value, background reference
* Extract a and b channels from masked stretch image
* Combine

***Gradient HDR compression, default settings

***Denoise
* Using luma mask, apply MLT with 4 layers, amount 0.5, 2 iterations first 2 layers and 1 iteration layers 3 and 4, thresholds 3 2 1 0.5

*** Clean up background
*Range mask 0.35-1, smoothness 2
*Add star_mask all for star_galaxy_mask. Apply inverted
*MLT on 8 layers on chroma, bias layers 5-8 -1
*histogram transformation, mids 0.6

***MLT stretch
www.stelleelettroniche.it/en/2014/09/astrophoto/m42-ngc19...

**Initial (fine details)
* created a new multiscale linear transform, kept 4 layers using linear interpolation
* diffed from original image to create a "blurred" version of original image
* extracted luminance from original, used as mask on blurred version
* used curves to create s shape in luminance and pump up saturation a lot
* pixelmath sum the 3, rescaled, back to original image

**Second (galactic colors)
* new multiscale linear transform, keep 5 layers
* diff from original
* extract luminance from blurred image, to use as a mask
* masked blurred image with its own luminance, gave it s-shaped RGB curve, big boost in saturation. Shift pinks to blues with H curve
* pixelmath sum the 3, rescaled, back to original image

**Third (galaxy arms shape)
* new multiscale linear transform, keep layers 6, 7, 8
* diff from original

** extract M31 structure only
* extract luminance from blurred image
* iif(inellipse(2400, 2200, 1250, 400), multi678_L, 0)
* clone out stars and M110
* histogram midtones to 0.2 - m31_mask

*masked blurred image with own luminance, gave big boost in RGB/K, some boost in saturation
* pixelmath sum the 3, rescaled, back to original image

***Local histogram equalization - kernel 192, contrast 1.5, blend 0.5

***Further galaxy adjustments (from www.lightvortexastronomy.com/tutorial-example-m31-androme...)
* Create galaxy_mask: Range mask 0.35-1, smoothness 2, iif(inellipse(2400, 2200, 1300, 450), galaxy_mask, 0), substract star_mask_all, clean edges with clone tool
* Apply
* MLT 8 layers chrominance, pump up bias on 5-8 0.025 0.025 0.05 0.05
* Color saturation raised blues a bit (widely) and reds quite a bit more (more narrowly)
* Remove mask

*** Darken
* DarkStructureEnhancer, 8 layers, 0.7, 3x3
* DarkStructureEnhancer, 8 layers, 0.7, 5x5

* Very slight s-shape on all image luminance

*** Sharpen
* Sharpen with multiscale linear transform, bias layers 2-6 (0.05, 0.05, 0.025, 0.012, 0.006)

Taken on: February 16, 2020

Tags:

dso

m32

m110

andromeda galaxy

andromeda

galaxy

pixinsight

takumar 135mm f2.5

takumar

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