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New stretching software: rnc-color-stretch released (free, open source)

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rnclark

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The rnc-color-stretch first release is now online.

rnc-color-stretch
rnc-color-stretch

Info and links to the download and install instructions are here:


Feedback is appreciated.

Roger
 
Thank you for the time putting this together, I'll download it soon and give it a workout.
 
Sir Canon said:
Sir Canon said:
rnclark said:
The rnc-color-stretch first release is now online.

rnc-color-stretch
rnc-color-stretch

Info and links to the download and install instructions are here:

http://www.clarkvision.com/articles/astrophotography-rnc-color-stretch/

Feedback is appreciated.

Roger
Click to expand...
YESSSSSS going to install it right now!

--
I tend to overdo things
Click to expand...
and offically i have no idea how to make it work :/
Click to expand...
What operating system and which instruction are you having trouble with?
 
chris gunn said:
Looking good!

I'm on Ubuntu, and haven't done a C compile in years. This will be a great excuse!
Click to expand...
Are you compiling davinci? I am on Mint, which is Ubuntu.

If so, I had to do the following:

run configure as instructed then edit the Makefile:

add to the LIBS line in the Makefile: -ljbig

so my libs line looks like:

LIBS = -lhdf5 -lcfitsio -lpng -lz -lm -lX11 -lSM -lICE -ljbig

Roger
 
rnclark said:
Sir Canon said:
Sir Canon said:
rnclark said:
The rnc-color-stretch first release is now online.

rnc-color-stretch
rnc-color-stretch

Info and links to the download and install instructions are here:

http://www.clarkvision.com/articles/astrophotography-rnc-color-stretch/

Feedback is appreciated.

Roger
Click to expand...
YESSSSSS going to install it right now!

--
I tend to overdo things
Click to expand...
and offically i have no idea how to make it work :/
Click to expand...
What operating system and which instruction are you having trouble with?
Click to expand...
windows 10. im not sure what to do with the text files

--
I tend to overdo things
 
Sir Canon said:
rnclark said:
Sir Canon said:
Sir Canon said:
rnclark said:
The rnc-color-stretch first release is now online.

rnc-color-stretch
rnc-color-stretch

Info and links to the download and install instructions are here:

http://www.clarkvision.com/articles/astrophotography-rnc-color-stretch/

Feedback is appreciated.

Roger
Click to expand...
YESSSSSS going to install it right now!

--
I tend to overdo things
Click to expand...
and offically i have no idea how to make it work :/
Click to expand...
What operating system and which instruction are you having trouble with?
Click to expand...
windows 10. im not sure what to do with the text files
Click to expand...
Well, his file is a C program which needs to be compiled. Different operating systems have different compilers etc.

--
cheers!
Gunn
-- Get a big lens and get closer™.
 
If anyone was trying to reach my server, the internet to the server went down last night for a little over 5 hours. It is back up now and hopefully stable. The server is fine, it was an ISP provider problem.

Roger
 
Thanks a lot for your efforts Roger.

I shall download this and try to give it a go.

Regards,

Vishwanath
 
I wouldn't mind playing around with it but, for a visual person like myself, i believe i'm going to need a video tutorial for this one ;0 .
 
rnclark said:
chris gunn said:
Sir Canon said:
rnclark said:
Sir Canon said:
Sir Canon said:
rnclark said:
The rnc-color-stretch first release is now online.

Info and links to the download and install instructions are here:

http://www.clarkvision.com/articles/astrophotography-rnc-color-stretch/

Feedback is appreciated.

Roger
Click to expand...
YESSSSSS going to install it right now!
Click to expand...
Click to expand...
Click to expand...
Click to expand...
Click to expand...
Click to expand...
 
jammeymc said:
I wouldn't mind playing around with it but, for a visual person like myself, i believe i'm going to need a video tutorial for this one ;0 .
Click to expand...
Yup, so much for a "One Click Fix".


PI is easier......
 
Last edited:
rnclark said:
chris gunn said:
Sir Canon said:
rnclark said:
Sir Canon said:
Sir Canon said:
rnclark said:
The rnc-color-stretch first release is now online.

Info and links to the download and install instructions are here:

http://www.clarkvision.com/articles/astrophotography-rnc-color-stretch/

Feedback is appreciated.

Roger
Click to expand...
YESSSSSS going to install it right now!
Click to expand...
Click to expand...
Click to expand...
Click to expand...
Click to expand...
Click to expand...
 
swimswithtrout said:
jammeymc said:
I wouldn't mind playing around with it but, for a visual person like myself, i believe i'm going to need a video tutorial for this one ;0 .
Click to expand...
Yup, so much for a "One Click Fix".

PI is easier......
Click to expand...
Frankly I think you're comparing apples and oranges here, and there's no reason why PI and Roger's stretching algorithm couldn't feature side-by-side in a person's astro workflow.

From a quick read-through three days ago, I gathered that once you have it running, you have to play around a bit with a couple of "stretching parameters" (off the top of my head, so correct me if I'm wrong, Roger) to find what works on a certain image. Nothing easier than entering some numbers and see what the effect is on the output image - and learn along the way what settings work for a certain type of image.

Also, someone is working on a GUI for Windows, which I guess will lower the threshold for many potential users. This being the first iteration of Roger's algorithm, I say applaud him for his efforts instead of whining, and who knows what the next version might look like from a user-friendliness pov!

cheers,
 
Thanks for your efforts, Roger! The blues in the Pleiades image you posted recently were a bit too saturated for my liking, by it's always easier to slightly desaturate to taste than the opposite, especially with respect to noise-control.

I will surely give it a go as soon as I find some time. And if by then the GUI for Windows is up and running, I'll gladly use it of course, but personally I don't think the present workflow should pose too many problems to those that are motivated to use it.

cheers,
 
Thanks for making this available. I'll briefly report what I did. Working on Windows 10 I downloaded davinci and installed it. Then I downloaded Roger's davinci script rnc-color-stretch-v0.936 and put in some suitable directory. That was all I needed. cd into that directory and call the script with

"c:\Program Files\Davinci-2.18\davinci" -f rnc-color-stretch-v0.936 ...

I haven't studied yet what all the options do but simply threw one of the example parameters onto one of my stacked files I did with sequator of some vintage. I'd have to reconstruct how I did the stacking but here is a result. Processed as

"c:\Program Files\Davinci-2.18\davinci" -f rnc-color-stretch-v0.936 m31seqAll1.tif -rootpower 50 -obase m31Alle14 -scurve2 -setmin 5140 5200 5650 -jpegonly -display -enhance 1.4

[ATTACH alt="Processed with "c:\Program Files\Davinci-2.18\davinci" -f rnc-color-stretch-v0.936 m31seqAll1.tif-rootpower 50 -obase m31Alle14 -scurve2 -setmin 5140 5200 5650 -jpegonly -display -enhance 1.4"]1557531[/ATTACH]
Processed with "c:\Program Files\Davinci-2.18\davinci" -f rnc-color-stretch-v0.936 m31seqAll1.tif-rootpower 50 -obase m31Alle14 -scurve2 -setmin 5140 5200 5650 -jpegonly -display -enhance 1.4

Here is a jpg from the original (the tif is too big):

The input file (converted from tif).
The input file (converted from tif).
 

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Last edited:
Greg VdB said:
Thanks for your efforts, Roger! The blues in the Pleiades image you posted recently were a bit too saturated for my liking, by it's always easier to slightly desaturate to taste than the opposite, especially with respect to noise-control.
Click to expand...
Yes I acknowledge that. The thing is, however, I didn't enhance the colors--those were the colors that are there. If you do a short exposure. you will see the strong blues. Example, the NASA APOD: https://apod.nasa.gov/apod/ap990301.html

The reflection nebulae in the Pleiades has multiple molecular clouds and at least a bimodal gain size distribution. I've seen research articles that say the dust is graphite grains with 10 to 100 silicon atoms, and another that says the grains are 0.1 micron in diameter. These sizes are in the Rayleigh scattering regime so the colors should be similar to our daytime blue sky (a good clear blue sky). Further, the Pleiades stars are bluer than our sun, which would make the light even bluer.

B-V photometry of the Merope nebula shows near Merope the color is -0.6, which is quite blue (see http://www.clarkvision.com/articles/color-of-stars/).

See: http://articles.adsabs.harvard.edu/...owOB...6..257E&defaultprint=YES&filetype=.pdf

Amateur astronomers stretching their images to bring out faint details compress the high end, thus losing color. So we commonly see the Pleiades nebula a lighter blue due to that loss of color. It is so commonly done, that the real blue now seems odd.

My stretching program avoids that problem. With enhance=1, it simply puts the colors in the stretched image that were there in the original but were hidden by the sky glow.

Roger
 
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