Posts Made By: James Brown

Hi All:

It's been a while since I posted any images here (about two years I think.) During that time I upgraded my camera to an FLI Microline 11002M. I've spent much of the summer and fall setting up my system and getting to know the new equipment. I spent a lot of time messing with my FLI PDF focuser and TEC field flattener. We had great skies for the November new moon a few weeks ago, and I was able to get quite a bit of data on several targets. The first target that I have fully processed is the Pelican Nebula, IC 5067-70 and the Eastern part of the North America Nebula, NGC 7000 in Cygnus.

The attached is a quarter sized and compressed version of the image. I don't have a proper web page, but a full sized (4008 x 2672 pixel) image is here, hopefully it will open up for you:

http://home.comcast.net/~jameslbrown/pwpimages/Pelican-NA%20windows.jpg

A half sized version is here:

http://home.comcast.net/~jameslbrown/pwpimages/Pelican-NA%20windows-half.jpg

This is basically an Ha-OIII image combined to form a synthetic green channel as described by Steve Cannistra. I also layered in regular RGB data which enlarged some of the stars, but brought in quite a few more stars.

Thanks for looking and commenting. I should have about ½ dozen images ready in the next few days (or weeks or...) .

Jim

TEC APO 140
TEC Field Flattener
Astro-Physics Mach 1 Mount
Finger Lakes Microline 11002 M, 2” Filter Wheel and PDF
Starlight Xpress Lodestar with Borg 50mm f5 Achro guide lens.
Astrodon LRGB Filters, Baader Narrow Band Filters
Maxim DL 5, CCD Commander, The Sky, Photoshop CS2, Focusmax

Roland Christen said:

http://www.telegraph.co.uk/science/picture-galleries/6169034/Astronomy-Photographer-of-the-Year-2009-competition-winners.html?image=4

Way to go Tom!!

Congratulations!

J

Hi Eric:

It looks like your web site is going to be very nice indeed. I like the top banner "Skies By Africa" quite a bit. The linked pages and images work quite well. The home page image M34 is maybe initially too big. At least on my computer you have to scroll left and right to see the sides, before you click on it. I personally like to see the whole image on one screen first and then scrolling is expected when you click on the image to get a full sized view. That's only my preference of course.

What package are you using to develop the web page? Is it a lot of work? I'd like to follow in your footsteps and put together something nice one of these days...

Jim

Hi all:

Hopefully you can share some experiences solving what I have found to be a very frustrating part of astro-imaging; namely, preparing an image for web display.

First let me set the stage:

I gather data as FIT files, calibrate and combine the various subs in Maxim. Then I save separate LRGB images as uncompressed 16 bit TIFF files with Maxim. I then stretch and combine these into a LRGB image (or Ha/OIII etc.) using Photoshop CS2. My monitor at home is regularly calibrated using an Eye-One calibration device. I primarily use the stretching and processing techniques shown in Ron Wodaski’s books. After processing in Photoshop I'll have a final TIFF image that I like: the colors are right, the black point is not clipped and the range of contrast is good to my eye.

For example, I have been working on an M33 image for a while, and I now have it as a final TIFF on my computer at home that I think is just spectacular. In particular the subtle and nearly perfect oval of very faint outer stars beyond the spiral arms shows well. You don’t always see this extended portion of M33 in web images. The blue arms and HII regions are really snappy. There are dozens of tiny background galaxies in the full scale version etc.

Now comes the problem part.

To post on Astromart, or I think other web pages, I need to create an 8 bit jpeg. It is easy enough in Photoshop to convert the data to 8 bit from 16 bit and save as a jpeg. When I do that, the image still looks fine in Photoshop. Then when I save it and open it with Windows Picture and Fax viewer or Internet Explorer, the image looks terrible! The colors are all wrong and the dark regions are severely clipped.

I can go back to Photoshop and use the “proof image” function set to “Windows RGB” to see how the image is going to look on my computer with a Windows viewer. When I do that the image initially looks too bright. But if I make adjustments to the jpeg image to make it look just like the TIFF, that ultimately makes the image look even worse on other monitors, like my un-calibrated monitor at work!

Here is a link to a ½ sized M33 that I post-processed in Photoshop using the “Proof Image – Windows” function. This image looks way black-point clipped on my monitors at work. All subtlety in the dim regions are lost:

http://home.comcast.net/~jameslbrown/pwpimages/LR%2BHaGB%208bit%20medium.jpg

Here is a link to the same image that I merely converted to an 8bit jpeg and saved. This one looks way too bright on my calibrated monitor at home, but it is still black-clipped at work! This image also does not show the subtlety of my original TIFF. It’s not even close.

http://home.comcast.net/~jameslbrown/pwpimages/M33%20half.jpg

Here are some possibilities I’ve been considering:

1. My monitors at work are seriously out of whack.

2. With a low-brightness extended object like M33 one is simply hosed when going from 16 bit to 8 bit.

3. I am missing a key conversion or processing step that would solve this problem. For example should I be identifying a particular color space in Photoshop at the beginning?

Any input from you all about similar experiences would be great. Also, let me know how the two M33 images look on your screen. Are the outer regions of the galaxy at all visible in either image? Are the colors OK or garish? Your input into this problem will be very much appreciated!

Jim

That's really cool!

Jim

Hi all:

It's been about a month since anyone has posted a M45 image. Here is my go at this beautiful object. I might try to re-process to minimize the bright star halos, but I might not. The halos don't bother me much and I don't want to dilute the reflection nebulosity. This is basic LRGB processing with 5 minute subs. A full-sized clickable version is here:

http://home.comcast.net/~jameslbrown/pwpimages/M45%20LRGB.jpg


I hope you enjoy one more M45! Thanks for any comments.

Jim


TEC APO 140
TEC Field Flattener
Astro-Physics Mach 1 Mount
Finger Lakes Microline 11002 M, 2” Filter Wheel and PDF
Starlight Xpress Lodestar with Borg 50mm f5 Achro guide lens.
Astrodon LRGB Filters, Baader Narrow Band Filters
Maxim DL 5, CCD Commander, The Sky 6, Photoshop CS2, Focusmax

Hi all:

The following images are of Cederblad 214, a relatively low surface brightness emission nebula in Cephus.

You might recall that I have been puzzled by the variation in jpeg presentation between my computer at work and my computer at home, when viewing images of dim objects. Astromarters Enrico Africa, Charles Hakes and others have offered excellent tips for making sure the colors of my high resolution 16 bit tiff images stay "right" when I convert to 8 bit jpegs. I think I have that part of the puzzle solved. Thanks guys!

I am still having black point issues though.

If you have a moment, take a look at the two images I’ve attached to the next posts. The first one looks nice on my calibrated monitor at home. This image is clearly and tragically black-point clipped at work, in other words the fainter nebulosity right up to the edge of the frame on the N, SW and W is gone and only the central nebulosity shows.

The second image has substantially boosted gamma (about 1.4) I also boosted the overall brightness a bit. At work this one looks like #1 does at home. At home this image is way too bright though!

If you guys could let me know which version is more aesthetically appealing on your monitors, that might help me figure out whether my home system is out of whack, or whether I should just quit looking at these on my work monitors.

Thanks for any input you might have! I’m heading up to the mountains this evening, but I will read all replies carefully on Sunday. Have a great New Years!

Jim

#1: This image of Cederblad 214 looks balanced to my eye at home, on a calibrated monitor, with faint nebulosity showing right up to the edge on the N, SW and W sides of the frame. At work this image is black-clipped and the faint peripheral nebulosity is gone.

#2 : This image has had its brightness boosted. At work, this one looks like #1 does at home. At home, this one is too bright!

Thanks for the comments guys. I am going to re-process this image with a different monitor, and I will remember to embed the sRGB color profile. This has been a very helpful experiment. Stay tuned for a final version.

Thanks!

Jim