What is your workflow or tips for OSC CCD processing?

[mcbbcn]

Hi again friends,

As I got your help to resolve the issue with the flats, I thought it would be worth it to go back in a new post to the overall topic of processing subs that are made with OSC CCD's.

I took a shot with my QHY8C (one-shot color CCD) of NGC6960.  The current shot is just a test one, and it's about 25min. from a light polluted location.  The image has been calibrated, debayered, star aligned, integrated, cropped & DBE & as a suggestion from Geert, I've applied star mask and noise reduction.

http://dl.dropbox.com/u/8971416/NGC6960_integrationv1_dc.fit

Typically, what I do after DBE is:

1. BackgroundNeutralization which does not seem to have any effect on my color camera.  It just seems to work for Mono CCD.
2. ColorCalibration which does not seem to have any effect on my color camera.  It just seems to work for Mono CCD.
3. Convert the image from non-linear to linear using STF and Histogram tool
4. ACDNR
5. HDRMultiscalteTransform i.e. Typically a value of 4
6. Histogram Stretch
7. SCNR to remove any Green traces

Now, I've received advise that the Mono processing & color processing are pretty similar, but I'm finding that steps like #1 & #2 does not seem to make any difference in the image.  The background and colors of the stars come out pretty well balanced after debayered & DBE.  Now, if you have a different flow for Color or any tips or tricks that can help me extract the color of the nebula without overly saturating the image, I would love to learn them.

So, more than improving the attached image, I'm mostly interested in your workflow when processing subs made with an OSC CCD.

Thanks again for all your help,

Miquel Casas
Portland, OR

[astropixel]

Hi Micquel. For saturation after stretching, having applied HWMT, I use LRGBCombination with the same L* mask that I applied after stretching.

L channel only - select the mask image and set the top slider to 0.5 and the bottom slider to 0.2 - experimenting with different values. Activate by clicking the square button.

Final adjustment with curves.

For different levels of saturation and detail I apply curves and HWMT to the L* image, as required.

[mcbbcn]

Hi Astropixel,

Thanks for your reply.  I assume you're processing using images from an OSC CCD, so how come you use LRGBCombination in an OSC image?  Do you create an Light image from the debayered image somehow?

I did some reading and I experimented with the tool HDRWT which I think is the one you mean, and I applied a star mask with some CurvesTransformation, and I've started to get some better results.

Also, if you're processing debayered images from a OSC CCD, it sounds like you don't use background calibration & color calibration, which it will confirm my suspicion which these functions do not have any effects (at last that I could notice) on debayered images.

Thanks for your help,

M.

[astropixel]

A couple of screenshots is more helpful. Just to explain my first post. Finally got to my PI computer

CCD/OSC or CMOS/DSLR

Starting with a processed integrated linear image (this one processed in BatchPreprocessing); then, very basically, to make the point about LRGBCombination of the L* channel/mask with an RGB image

ABE

ColourCalibration

HistogramTransformation

SNR (forgot this step on the images below)

HDRMedianTransform (image)

LRGBCombination of L* channel (image) - saturation

Curves - contrast.

Sure, there are other steps such as ATWT for noise reduction, or ACDNR, if you want.

And manipulate the mask for different effects, lighter, darker, more or less contrast.

[mcbbcn]

Hi Astropixel,

Thank you.  This is a completely different process that I'm used to, so I'm sure I'm going to learn a lot.

I was not familiar at all with the use of the LRGB Combination tool for OSC images, so I'll definitely learn more about it.

...& your workflow is totally different from what I do with my mono CCD, which I'm happy to discover that the OSC workflow and the Mono workflow are different.  I was told that they were about the same, but I could not get my head around it, as some of the Mono steps did not seem to make any difference with my OSC subs...

I appreciate a lot you sharing.  I'm attaching the latest processing that I did last night.  It's still 25 min. exposure from a bortle 8 location so it's not too bad, but now I'll try your workflow and see what happens.

http://dl.dropbox.com/u/8971416/NGC6960/NGC6960_integration_before_DBE_SM_SCNDR_SM_HDRWT_CurvesTransform.jpg

It's in jpeg format because I sharing it over email with my dad last night, but for taking a look at the progress, it's probably good enough.

Thanks again for all your help,

M.

[astropixel]

...& your workflow is totally different from what I do with my mono CCD, which I'm happy to discover that the OSC workflow and the Mono workflow are different.  I was told that they were about the same, but I could not get my head around it, as some of the Mono steps did not seem to make any difference with my OSC subs...

I have very little experience with mono LRGB processing - channel combination etc. I would have thought that once the image is integrated that there is little difference in post processing compared to an integrated OSC image - perhaps not?

[mcbbcn]

You may have little experience with LRGB, but the image you posted is fantastic.  You have awesome skies & awesome skills!  Thanks Astropixel!

[mcbbcn]

Hi Astropixel,

I tried to apply LRGB Combination over the image but it says it's not compatible.  It'll let me select the star mask but not the image.  Do you do anything with the image to make it compatible with this function?

Thank you,

M.

[astropixel]

You may have little experience with LRGB, but the image you posted is fantastic.  You have awesome skies & awesome skills!  Thanks Astropixel!

That's very nice, I wish it were true, but I just got lucky with that one

I tried to apply LRGB Combination over the image but it says it's not compatible.  It'll let me select the star mask but not the image.  Do you do anything with the image to make it compatible with this function?

OK. Once you have stretched your image with HistogramTransformation, apply SCNR without a mask and them extract the L* Channel.

Menu bar - select, Image > Extract > Lightness (CIE L*) and set the extracted image as your mask - Inverted.

Then do whatever processing - ACDNR, MedianTransformation, ATWT, whatever.

Then set up LRGBCombination as in the second image that I posted earlier. That is, deselect RGB and leave L selected. Choose your L* image as L. Click the blue square button - it wont work if you select the round global button. You should have no errors now.

[mcbbcn]

Neat tip! I tried and it worked.  Thank you so much.  I'll finish processing my mini-25 exposure, and I'll post.  I appreciate all the help.  M.

[mcbbcn]

Thanks a lot Astropixel.  I'm learning a tone.  Here is the result which is not too bad for 25-min exposure from a highly LP sky....

[astropixel]

That's coming along nicely. Alejandro Trombolini has provided some detailed processing examples in this sub forum. Particularly dealing with linear images. Harry has a video on linear background noise reduction too. I think Juan posted an example a while back. A search should turn it up.

[mcbbcn]

Thanks Astropixel.  I just finished processing the 25min. exposure in PS, and this is the result.  It's a bit of postcard approach, but it helped me deal with the star halo.