LRGBCombination issues

[Spaceade]

Got a shiny new CCD to replace my DSLR and have being takin a crack at LRGB imaging to see what its all about. Everything was going swimmingly until i came to using LRGBcombination towards the end and it all goes pair shaped!

Have been following Vicent & Harrysastroshed for there tutorials on this, however once i combine my luminance onto my RGB instead of a prettier RGB i get a virtually white image with basically no color or improvement at all. Ive tried messing with both the transferfuctions and channelwieghts sliders, to no avail.

I used an M101 sample off lightvortexastronomy to check if it was just me flopping at astrophtography, however I get the same result. As recommended elsewhere i apply a permanent histogram transformation using the screentransferfuction as a base to both luminance and RGB before mashing them together. Messing with the histogram on the final image gets me nowhere either.

For clarity, here is the Stretched RGB, luminance and final image. Also attatched a link to the TIFF's, if thats any help.

LRGB

LUM

RGB


https://drive.google.com/drive/folders/0B6aPQ3_yz8PBbHF0aUZhdUhJb2c?usp=sharing

Thanks.

[aworonow]

You say you're showing stretched images "for clarity." To apply L to the RGB image, both the L and the RGB should be processed separately into a nonlinear stage (stretched). Then you load up the L only in the LRGBCombine tool and drop it's triangle onto the stretched RGB image.

Alex W

[Spaceade]

Alex,

Yep thats the process i use:

• Apply a permanent stretch separately to both LUM and RGB using the histogram transformation tool to make them nonlinear, using the STF as a guide.
• Select only the LUM in the LRGBCombination tool, and then apply that to the RGB

Beyond that, ive had no luck fiddling with the LRGBCombination tool sliders or the using histgramtransformation tool post-combination.

[pfile]

i can't speak to the problem at hand, but those images really need a trip thru DBE to get rid of all those gradients before doing anything else...

rob

[Spaceade]

Rob,

It shouldn't make a difference, but i tried it anyway. still same result.

Intrestingly whenever i exact a lumininence from the stretched RGB image i get what appears to be a linear image (with only bright stars and galaxy core visible), which is against both what ive done in the past and what others get with their images.

This got me thinking and led me to reset by global pix configuration settings.....and it fixed it!,i get nice pretty LRGB images now.

Never could find the parameter that affected this manually 

[aworonow]

As far as I can tell, the problem is that the image quality is extremely low...especially the RGB. I downloaded it and the lum. Cropped away the edges, which have very extreme colors present. Then did DBE--the gradients are just about as bad as the color edges, background neutralization, and SCNR on the green. Then added in the L. The result is reasonable, I think, give the low quality of the initial RGB image. I think ignoring the gradient and edge problems led to your problems. Also, the RGB stretch is pretty weak...maybe due to the other problems too.
I've attached my quickie result (very low resolution). Not great, but ok as a quickie, I think. What you really need is more integration time, is my bet, plus more processing before introduce L.

Hope this helps,
Alex W