Author Topic: HDR - Individual sets against fully stacked version  (Read 115 times)

Offline m_abukhalid

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HDR - Individual sets against fully stacked version
« on: 2018 September 16 15:26:30 »
Hello all,

I am working on an andromeda galaxy series of shots that I took (17X 3min, 28X5min, 11X10min). I stacked the whole bunch and then it occurred to me that with the center all blown out I might benefit from some HDR. I attached a copy of a print screen of the stacked image after preprocessing (Integration, DBE, color cal, SCNR). What Im wondering is do I stack each set separately and combine them with HDR composition or since I have a fully stacked image with all the data, do I just need to HDR the final integrated image with the shortest exposure length (3min)?

Offline monkeybird747

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Re: HDR - Individual sets against fully stacked version
« Reply #1 on: 2018 September 17 18:34:07 »
I just finished an HDR Composition of Andromeda a few days ago. The tutorial I read (LVA) had you calibrate, integrate, and DBE the individual exposures, then use the HDR Composition routine on the resulting integrated images. For me I only had 300s and 60s frames, so I used HDRComp on two fully preprocessed and integrated images. I suppose in this fashion you would lose the benefit of stacking more images and the associated gains in SNR. I'm not 100% on that part though. For a target like this that may not be much of a consideration.

For Andromeda I had to significantly reduce the Binarizing setting to get the amount of masking of the core I wanted. The default settings only masked a tiny dot at the center of the core, and I wanted to replace more of the saturated core with the 60s exposures. I also bumped the smoothness up to 20 or so. All this had the effect of including a handful of the most saturated stars in the mask, replacing them with the less saturated versions of the 60s exposures. This was my first attempt at this process, so please take with a grain of salt. After this was photometric color calibration using Sb galaxy profile. I saved the HDR Multiscale Transform for near the end of processing. Final version linked below.

https://astrob.in/366999/0/