M17 Color

[Stargazer_Ken]

Hi Folks,

Also a newbie but have been reprocessing old data like mad and learning along the way. I processed an M17 image and have interesting colors. I suspect that StarTools actually did the correctly but everyone else's is mostly if not all red. Mine more resembles some of the images that were done with line filters. Take a peek and see what you think. Of course the original fts file is quite large (207mb) and I don't have any file sharing set up at this point.

M17 Colors

M17 DCRaw-ST.jpg (287.21 KiB) Viewed 11517 times

Ken

[Stargazer_Ken]

P.S. Suppose I should have included it was done with a Canon T2i. I ran the CR2s through DCRaw using the command line I found here in the forums to remove the white balance. I found I also had to add an argument so it wouldn't use the rotation information from the camera. DSS doesn't like rotated files!

Ken

[Stargazer_Ken]

Ok, put the stacked, not white balanced FTS file on Google Drive for anyone who wants to play with it.

https://drive.google.com/file/d/0B7HOeR ... sp=sharing

The image on this page looks a lot like the color in mine.

http://apod.nasa.gov/apod/ap140527.html

Ken

[Rowland]

Ken. Just to be clear? Is the camera astro modified, and what calibration, if any, has been applied to the images? Reading your post I get the impression that you converted a set of light frames with dcraw and stacked them. I'm interested to know which dcraw options you are referring to and whether you mean DSS handles or does not handle rotated/flipped images.

[Stargazer_Ken]

Hi Rowland,

It's a factory camera, no modifications at all. The images were taken looking to the south, directly toward the light pollution of Colorado Springs. I am really impressed with StarTools ability to deal with that light pollution. If it had been modified to have the IR filter removed, I would have expected much more reds.

Here is the version of DCRaw I downloaded:

http://www.centrostudiprogressofotografico.it/en/dcraw/

One of the StarTools threads that mention the command is:

http://forum.startools.org/viewtopic.ph ... craw#p3029

When I ran the DCRaw command as mentioned and tried to stack the resulting tiffs in DSS, it gave me an error that the images weren't all the same size. I looked at the sizes and saw that some were landscape and some were portrait. Same dimensions, just rotated, X and Y sizes flipped. Apparently I had the auto-rotate function of the camera turned on when I took the photos and apparently over the time I took the subs, the camera thought I was switching between portrait and landscape. And DCRaw obligingly rotated those that the camera thought should have been one way or the other and DSS saw them as different image sizes. So, I looked at the DCRaw Man page to see if I could fix that. If all the images were one way or the other, DSS would have been happy (I wouldn't have been, I prefer landscape). The mixture on the other hand didn't work.

From the Man page for DCRaw:

https://www.cybercom.net/~dcoffin/dcraw/dcraw.1.html

-t [0-7,90,180,270]
Flip the output image. By default, dcraw applies the flip specified by the camera. -t 0 disables all flipping.

The DCRaw command line I am using which adds the "-t 0" is:

-v -r 1 1 1 1 -4 -T -S 32767 -k 0 -o 0 -t 0 *.CR2

And since my version of DCRaw has a different name, I use it's name before the arguments so the total command looks like this:

dcraw-9.26-ms-64-bit.exe -v -r 1 1 1 1 -4 -T -S 32767 -k 0 -o 0 -t 0 *.CR2

No calibration to the images. DCRaw is taking the raw CR2 images straight from the camera and making the tiffs based on the above command which removes the white balancing and writes the data as a 16bit linear tiff and disabling other repair functions. It's possible that since I didn't get DCRaw straight from the main site that it is somehow changing the data. I may try the version from the author's site just for grins.

Ken

[Rowland]

dcraw -4 -o 0 -D -t 0 -k 0 -H 1 -T my_raw_files

Ken. Try the options above. This will create 16bit integer CFA monochrome no flip/rotation tiff files. So no matter what the camera rotation all files will be the same orientation. Stack in DSS. This should produce an RGB stack. Ignore the white balance. That can be adjusted in ST.

[Stargazer_Ken]

For grins, I had DSS use the CR2 files and told it to use the camera WB. I selected No Background Calibration. I got pretty much the same results though this time I pretty much took all the defaults and skipped the fancier stuff like HDR and Magic etc. Pretty much processed like this in another thread (though I binned after wipe instead of before).

Load the data (using Open or LRGB), indicate it is still linear (this switches Tracking On).
Develop or AutoDev to see what we have got.
Fix stacking artifacts with Crop
Fractionally Bin the data with Bin if 1 unit of detail does not fit in 1 pixel until it does (or leave some oversampled data for deconvolution if desired and noise levels allow).
Wipe away light pollution gradients and signal bias.
Redo Develop or AutoDev for final global stretch.
Deconvolution
Use Contrast (for medium-large) and HDR for (medium-small) local dynamic range optimization
Use Sharp (with mask that Deconvolution made) for detail enhancement
Color calibration with the Color module
Switch tracking off for final noise reduction.

Here is the result!

M17 Camera WB-ST.jpg (193.76 KiB) Viewed 11493 times

Since I didn't change defaults, the red is a little wimpy. Looks weak on my "calibrated" monitor and almost non-existant on my non-calibrated monitor. But, the blue is still there!

Ken

[Stargazer_Ken]

dcraw -4 -o 0 -D -t 0 -k 0 -H 1 -T my_raw_files

Ken. Try the options above. This will create 16bit integer CFA monochrome no flip/rotation tiff files. So no matter what the camera rotation all files will be the same orientation. Stack in DSS. This should produce an RGB stack. Ignore the white balance. That can be adjusted in ST.

Used your options to make new tiffs. Must be missing something, a setting in DSS perhaps. I get a monochrome image out of DSS. It doesn't make an RGB.

Ken

[Rowland]

interesting. debayer should produce rgb images as it does with other programs. Very weird. I have debayered numerous sets without issue.

[Stargazer_Ken]

Roland,

I have uploaded 10 of the CR2s, zipped, about 223mb. Please download them and see what you get.

https://drive.google.com/open?id=0B7HOe ... authuser=0



Thanks,
Ken