So I used DSS to stack some photos we took of Orions Nebula, RGB.  What it gave me was a grey picture, how do I go about enhancing this to bring out the color and make it look good? Im very new to this...this is the first picture I've ever taken. Thanks for any information! :)

Jarm311:

... how do I go about enhancing this to bring out the color and make it look good?

That depends on how you took the original images, how you stacked them, and what you mean be "look good" ...

If, for example, you took the data with a monochrome camera and did not use filters, then you're stuck with a monochrome final image unless you want to "cook" the data and arbitrarily assign color to it.

If you did use color filters with a monchrome camera, then the color balance in the final stack depends on how you assign the original images to the different L, R, G, and B components during the "combine" operation.

If you used a color imager, then the color you see in the raw data is a function both of the actual color in the nebula and the way you process the data afterward.

Tell us more about the original data and we can help more ...

 Ok, I will tell you exactly what we did. It's the departments camera, so I know nothing about it, I just know how to operate it.  First, we pulled off the secondary mirror and replaced it with the camera. We then took 3 exposures of the Nebula (we were just testing the camera this time, not really going for picture of the year), 15 seconds w/ red, 15s with green, and 30s with blue. I then stuck them in DSS and clicked 'stack checked items'.  The resulting image was awesome, but without color.  I stacked them in Photoshop as well, and while I got color, it didnt look as good as the DSS stack. Here is the one I did in Photoshop, and what I mean by 'look good' is to have this same color, but with the prominence of the DSS stack.

Hope you don't mind Jarm311,  but I screwed with your photo a bit,  didn't focus at all because it begins to pixelate to much. You can get all kinds of free photo software here  http://www.download.com/windows/digital-photo-software/ 

Jarm311:

 Ok, I will tell you exactly what we did. It's the departments camera, so I know nothing about it, I just know how to operate it.  First, we pulled off the secondary mirror and replaced it with the camera. We then took 3 exposures of the Nebula (we were just testing the camera this time, not really going for picture of the year), 15 seconds w/ red, 15s with green, and 30s with blue. I then stuck them in DSS and clicked 'stack checked items'.  The resulting image was awesome, but without color.  ...

OK, then the problem is that you didn't get enough color in the raw data. That is, you didn't make enough exposures for the color to be "stronger" in the finished stack. Even with a bright nebula like M42, you need lots of exposure time to register the colors.

By "pulled off the secondary mirror" I'm assuming you were using an SCT and installed a HyperStar imaging system in place of the secondary. This gives you the abiity to make decent images with much shorter exposures, but even so you need more to bring out color.

M42 is simultaneously an easy target and a difficult one. It's easy to get an exposure that shows you it's a nebula, with a nascent star cluster growing from it, and that it has a cupped shape. It's difficult if you want to show all the detail in that shape, the full extent of the nebula, and a properly-exposed image of the cluster stars in the same image. The basic technique with an object like this is to overexpose for the details, and underexpose for the highlights, then mask the two separately when combining the images. This is where Photoshop is so valuable.

By contrast, what you were doing is a modified "snapshot" ... you (not simply, but basically) took unmodified separate exposures of through each color filter and added them together. A modified method (depending on the sensor in the camera, and the density of the filters) might have had you making longer exposures through the red, and several times as many as those of blue, longer (but fewer) exposures yet of green), and shorter exposures of blue, plus perhaps some h-alpha exposures to add in as luminance frames in a final LRGB stack. Something of that nature is needed to give the "magazine quality" color image you might have been expecting to see.

When you edit images in that way, you're making conscious decisions to render it the way you expect it to be -- and that almost certainly differs from "reality". That's okay ... if you're making a photo in such a way you're basically making it for the sake of "pretty pictures" and there's nothing wrong with that. One of the members here (also a Moderator), Jay Ballauer teaches such techniques as a method he calls celestial "landscapes" -- he advises his students and colleagues that what they are doing is rendering these images a certain way as to be pleasing, for whatever reason the imager has in mind. He teaches us how to use the tools to create these landscapes, why the tools have the effects they do on the images, and how to determine what the object "should" look like if rendered via a particular method.

He's not saying that an object MUST look a particular way; he teaches how to use modern imaging and processing technology as an artist would to depict reality through his or her own imagination. He doesn't generally call this art, but he does talk about the effort it takes to learn the art of imaging. It's not exactly intuitive, but it's not rocket science once you begin to look at it that way. It's technical, and the more skill and practice you bring to it, the more you can shape the image to your vision.

If it's a scientifically accurate image you're after, then the problem you have in determining how to render the color is finding out how much of each color is actually in the object to begin with ... and that's more difficult than most of us imagine. Do you want to render it as it would appear if you were floating in space one light year away? Ten light years? What? This is why most of us who image apply our own sense of how we want the image to look, rather than trying for absolute verisimilitude (hate that word, but it's the one).

Back to your particular images: I don't know what you mean by "prominence of the DSS stack" ... but if what you mean is for the color to have the same strength, then you need to know what DSS is doing with the colors and what sort of processing is taking place. I've used DSS a bit, and unless you use specific processing instructions it is fairly automatic (meaning you can't really tell what it's doing). That makes it easier to apply, but harder to use in the "landscape" mode I mentioned above. Still, I suggest that to alter the strength of the color for this object, you should look at some images you really like, approximate the relative amounts of red, green, and blue that are in those images, then take additional data in those amounts and try a new stack. Remember, however, that if you expose for the details in the nebula the star cluster will blow out the center of the image ... so you must take some additional frames where the brighter bits of the nebula are "properly" exposed (this will mean there will be very little detail in the balance of the nebula) and then process these stacks separately. After you have the detail stack and the highlights stack processed separately, you can mask out the overexposed highlight area in the detail frames and layer in the properly-exposed highlight in its place.

Did that make sense? If you look at Ron Wodaski's book or Web site (The New CCD Astronomy) you'll find this nebula and M31 are processed in similar fashion and the examples there are very helpful.

 Wow...Thank you sir, for the vast amount of information you have just laid upon me. What I gather from all of this is that Astro-imaging is not nearly as simple as point and click. Wow, I really appreciate you taking the time to explain all that to me. When you say LRGB, what do you mean by luminence...is that just clear? I can't even explain to you how helpful all the things you have told me are, Thanks again. I will check out that guys website, especially since I will be going out this weekend to a darker area. I will post pictures here when I get back...to see what I did with what I learned :) then y'all can let me know what to improve. I will most definitely try Orion again, and I will do it right this time.  If 15 seconds over exposed the center, what would you recommend to make the detail in the center come out.  Maybe a 5 second exposure, or even smaller? I see you're in Dallas, I'm not to far from you, I currently reside in Waco.  Take care!

" Hope you don't mind Jarm311,  but I screwed with your photo a bit,  didn't focus at all because it begins to pixelate to much. You can get all kinds of free photo software here  http://www.download.com/windows/digital-photo-software/ "

Yea, Unfortunately I don't know how to mess with picture sizes on the camera, so they remain pretty small.  Thanks for the link!

-Jarm

If you're in or near Waco, then you should check out the Austin Astronomical Society and/or the Central Texas Astronomical Society, either of whose members you should find very helpful to you.

Jarm311:

... When you say LRGB, what do you mean by luminence...is that just clear?

Generally, yes. Stacking software often allows you to specify either an RGB stack or an LRGB stack. What that means is that it expects you will load all your red-filtered shots to be stacked to form a single R image, all the green-filtered ones for a G image, and so forth. You can substitute unfiltered (clear) or h-alpha filtered (to show different detail) images for the L stack. The software will then create a final stack from these. Using a highly-detailed monochrome shot to add to a color stack often greatly improves the detail in the final image.

... I will check out that guys website ...

Visit http://www.allaboutastro.com ...

If 15 seconds over exposed the center, what would you recommend to make the detail in the center come out.  Maybe a 5 second exposure, or even smaller?

Yes, that would be a good start. It all depends on your aperture, the light-pollution conditions, and the ISO rating or sensitivity of the camera. If it were me, I'd make a set at 5 seconds and another at 8 just to be on the safe side.

Make lots of them. Twenty or thirty would not be too many. The more you take, the more you have to choose from to get the "best" stack possible -- even if you decide the proper number for a good exposure stack is only 10 or 12 images.

Do you know about dark frames? These are frames made with the telescope and camera covered (let no light reach the chip) for the same length of time as the "real" (light) exposures. The idea is that what you get in the end will be a picture of the camera noise -- which also varies by temperature. A good procedure is to take 10 dark frames at each exposure setting, then average them (a program like DSS will do this for you automatically if you provide it the raw frames). Doing this can greatly reduce the noise in a stack of images -- especially if there are fewer images in the stack than there really should be.

   Thank you very much sir.  I was going to put all this info into action tonight, but our plans got screwed up :(.  So we are now planning to try again on the next new moon. I had looked into going to a CTAS meeting a while back, but I never go around to it.  Ill make sure to go and check that out.  Thanks again!