StarTools

I was originally a Photoshop User that switched mainly to StarTools quite awhile ago and have been very satisfied. Great Product! I watched a recent YouTube video from Tony Hallis that shows his very unusual processing for DSLR's.

https://www.youtube.com/watch?v=PZoCJBLAYEs#t=39

Basically he doesn't use any calibration frames but instead adjusts his raw images with Adobe RAW before feeding them into a stacker and then into his processing program. I agree with him on dithering instead of darks, as this has worked for me for awhile. However, the rest of his presentation goes against the grain. However, he does produce some great results. What do you think about playing with the subs in Adobe Raw before feeding them into a stacker and the result into StarTools?

TimN wrote:I was originally a Photoshop User that switched mainly to StarTools quite awhile ago and have been very satisfied. Great Product! I watched a recent YouTube video from Tony Hallis that shows his very unusual processing for DSLR's.

https://www.youtube.com/watch?v=PZoCJBLAYEs#t=39

Basically he doesn't use any calibration frames but instead adjusts his raw images with Adobe RAW before feeding them into a stacker and then into his processing program. I agree with him on dithering instead of darks, as this has worked for me for awhile. However, the rest of his presentation goes against the grain. However, he does produce some great results. What do you think about playing with the subs in Adobe Raw before feeding them into a stacker and the result into StarTools?

Hey Tim,

While dithering can indeed greatly alleviate the need for dark and/or bias frames, like you say, Tony is unfortunately very much incorrect on a number of things, which starts straight out the box with a DSLR is not a CCD camera. The QHY8 and Nikon D50 used the same CCD chip for example. I could be accused of being pedantic here though; I think he's merely trying to say make a distinction between off-the-shelf consumer cameras and cameras optimised for scientific data acquisition.

However, noise considerations are pretty much the same and what he calls "Color Mottle" is not an inherently physical phenomenon or an attribute of a CCD chip; Color Mottle is *introduced* by Tony and his use of Adobe Camera RAW. The debayering algorithms and noise reduction filters in Adobe RAW look for correlation and *introduce* this correlation. Give me a RAW frame and I can show you a nice poisson noise (not correlated noise) guaranteed, simply by using the correct debayering method.

Dithering is only effective to reduce *fixed pattern* noise; his color mottle is simply the result of transformed (by the debayering) random shot noise; the 'Color Mottle' is never in the same place, so dithering isn't required to fix that.

Tony's solution to use dithering is just a very roundabout way of fixing up his initial error of debayering his frames with Adobe Camera RAW. It's really a less effective way of applying Bayer Drizzle (scroll down the full page) of the RAW frames.

It gets worse with Tony's 'pre-processing'. Straight off the bat he starts messing his data in Adobe Camera RAW. For starters it's already debayered and color balanced, which increases noise, causing his 'Color Mottle'. Then he applies chromatic aberration correction (making the data no longer usable for deconvolution in a mathematically sound way), applies noise reduction (increasing 'Color Mottle' even more and destroying faint detail, while making deconvolution pretty much impossible) and applies sharpening. Worse, he's doing this on a per-frame basis, completely ignoring the fact that a stacked image with higher SNR would at least help the smarter noise reduction and sharpening algorithms to distinguish between real detail and noise.

All the while he seems he's under the impression that his data is 16-bit. It's not. It's 14-bit (most of which go to waste, but I digress). Because he hasn't stacked yet.

But he makes it worse. Let's stretch everything, making any non-linear process completely useless.

At this stage he's basically now shooting in JPEG, perfectly mimicking the way on-board processing makes data unusable for AP, his only saving grace being that his data is still 14-bit instead of 8-bit and that it has not been compressed with a lossy codec.

In particualr at 19:30 he is talking about graininess and spurious colors having vanished; the last remnants of any signal he's just proudly obliterated.

This makes me very, very sad....

EDIT: took a chill pill and toned it down a little - was not happy when I saw this video; he's doing a lot of budding astrophotographers a great disservice here.

Thanks Ivo, what you say makes a lot of sense. Thanks again for saving me the time of trying out some of his ideas. I'll keep dithering - as I was before - but back to my normal processing routine.