Swan Nebula, reprocessed

[DavidNg]

Hi,

With the help of IIS members, I have reprocessed the existing 17 hours LRGBHa data using PI. Star colors are somewhat more natural, the nebula is still a little washed out, every attempt I've made to reduce brightness also removed surrounding red hue, turned it into blueish, so I left as it is.
The bottom 5th appears a tinge blue, I am not sure where it came from, more likely from cloud or FOV hitting dome edge during blue filter frames.

About 10Mb hi-re link: http://www.astrobin.com/full/51331/?mod=none

The attached image was taking from the screen with screen capture program, heavily cropped to fit allowable 200Kb. What would be the best way to save or create the attach image balancing size and quality?

Thanks
David

[Larryp]

Looks great, David

[jase]

David, a marked improvement on your previous post of this target. Ha blends are tricky at the best of times. You've worked out the basics and still have good star colours to boot. You should be happy with the result. The target has OIII emission so don't suppress it the blue too much. Well done.

[mithrandir]

David, just about any image processing program, including GIMP and Photoshop, will let you resize and compress to fit within the limits.

With GIMP there is an add on called RIOT that lets you say how big you want the file to be and it computes a compression to fit that size. In most cases you'll find that a size around 1 megapixel will let you keep JPEG quality above 90%, but it becomes a matter of trial and error to find the best compromise.
Here's your 10MB image shrunk about as far as possible while keeping quality above 90%, so it is reduced to 20% of full size.

[gregbradley]

That's an excellent image David. My only comment would be to tone down the candy pink colour of the main neb. Gee you got a lot of the background faint Ha. What scope was this? It looks like an AP155 with reducer?

Star colours are superb. The blue bit down the bottom would be actual so don't worry about that. I don't think its an artifact just a deep image.

Greg.

[DavidNg]

Thanks every one, indeed I am thrilled with the Swan, keep showing off to my wife all day :)

Mithrandir, is there similar function I can find in Photoshop? The "save for web" in PS always gave me a tiny thumbnail image for 200Kb limit, otherwise I will have to learn how to use GIMP.:mad2:

Jase great help from your advice, much appreciated.

Greg, yes thats the scope with reducer. I will keep the tone done when I reprocessed again, was too excited, boosted the red to the max :)

Cheers

[gregbradley]

In Photoshop click image/image size/ change size to 350 and then use save as and save it say to desktop for ease of finding it. You will be given a little box that tells the size of the intended save. If its still over 200kb then resize again a bit smaller like 300. Make sure you convert to 8bit first under image/mode otherwise jpeg is not an option for saving and file sizes will be larger.

Greg.

[pluto]

In Photoshop go to File>Save for web
In there you can change the size and compression and it will tell you how big the resulting file will be and it shows how the image will look after compression.

[strongmanmike]

I can see why you are showing this pretty bird off to your wife David :)

Perhaps a tad purple around the swan itself but hey, some nice star colours there and a great field of view :thumbsup:

Mike

[DavidNg]

Thanks Greg, Andrew, Hugh and Mike. I have managed to reduce the pinky candy colour of the main nebula. Playing with PS settings I discovered that adjusting Hue/Saturatio of Red and Magentas did the jobs. Also saved at 8 bit mode allowed larger file size and quality. I chose 80% quality and 45% original size.

Link to 10Mb file:http://www.astrobin.com/full/51505/?mod=none

Regards
David