[CASSINI] Image junkies take note: Approach pics to Saturn now available from JPL

....GIF animators take note: JPL's started putting up a large series of
pre-SOI approach images. Might be worth looking at for those wanting
to piece together a quick'n'dirty approach animation.

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

On Sat, 03 Jul 2004 15:20:49 GMT, Bruce Palmer
wrote:

I actually did a test with three of them. One each from the R-G-B pics,
and combined them into 1 color image. It came out pretty good! The
image registration all lined up nicely. Of course finding the R-G-B
filtered pics is a bit harder.

....What exactly were the procedures you too to merge these,
step-by-step? I'm assuming you did it in Photoshop, right? As
embarassing as it is to admit it, all my work has been in separations,
not mergings, and I'm curious as to how you did it lest I waste my
time experimenting :-)

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

OM wrote:

...What exactly were the procedures you too to merge these,
step-by-step? I'm assuming you did it in Photoshop, right? As
embarassing as it is to admit it, all my work has been in separations,
not mergings, and I'm curious as to how you did it lest I waste my
time experimenting :-)

While I mostly use custom-designed applications, I sometimes use Adobe
Photoshop, either version CS or 7.0, which is perfectly acceptable for
most image processing.

That said, the easiest way in Photoshop to do RGB merges, at least for
me, is to use the technique described at

http://www.aecom.yu.edu/aif/instruct.../merging01.htm

The upshot is that you open the "Red" image first and then past the
"Green" image into the "Red" image's green color channel and the "Blue"
image in to "Red" image's blue color channel.

Alternatively, one can use the Merge Channels feature, which is a bit
more kludgy, in my opinion. Just open (and keep open) all three images
taken through the appropriate R, G, & B filters, respectively, all of
which must be of the same dimensions, and change their Mode to
Grayscale. Then go to the Channels Palette and hit the drop-down arrow
and select Merge Channels. When the dialog box pops up, hit the
drop-down and select Mode: RGB Color and Channels: 3. Hit OK and the
Specify Channels box pops up. Just make sure the appropriate files are
placed into each and hit OK and, voila, Photoshop does its magic.

--


Alex R. Blackwell
University of Hawaii

OM wrote:
On Sat, 03 Jul 2004 15:20:49 GMT, Bruce Palmer
wrote:

I actually did a test with three of them. One each from the R-G-B pics,
and combined them into 1 color image. It came out pretty good! The
image registration all lined up nicely. Of course finding the R-G-B
filtered pics is a bit harder.

...What exactly were the procedures you too to merge these,
step-by-step? I'm assuming you did it in Photoshop, right? As
embarassing as it is to admit it, all my work has been in separations,
not mergings, and I'm curious as to how you did it lest I waste my
time experimenting :-)

Like you, I didn't want to waste time trying to figure out how to do it
in Fireworks (I don't have Photoshop) so I reverted to trusty Picture
Publisher 8 (now 6 years old) where I knew exactly what to do from past
experience. RGB image, split into channels, cut-n-paste, recombine.

In Fireworks you'd probably use layers and combine them with some kind
of settings for blending. Something I obviously don't know how to do.
The key seems to be separate grayscale images that are all the same
size, no matter what package you use.

I'll defer to Alex's post for the Photoshop details.

It gets more complicated if the RGB grayscales don't line up exactly. I
have some GIS mapping software that will do 3-point registration on
images but I'll need to find some spare hours to try that out on the
Cassini photos. But first I'm going to try and find a plugin that will
do the same thing. That would greatly simplify matters.

--
bp
Proud Member of the Human O-Ring Society Since 2003

Bruce Palmer wrote:
In Fireworks you'd probably use layers and combine them with some kind
of settings for blending. Something I obviously don't know how to do.
The key seems to be separate grayscale images that are all the same
size, no matter what package you use.

Just a quick update. Fireworks doesn't do RGB channel separation.
Photoshop does. Picture Publisher does. Fireworks is positioned as a
tool for web designers and apparently they decided to leave out features
normally associated with publication and pre-press work.

FWIW I found there are a lot of special-purpose image processing
applications out there for use in astronomy. One overview can be found
at...

http://www.yahoos.info/index.php/Sci...Data_Analysis/

Mira AP at http://www.axres.com/mira_ap_features.htm looks very nice.
So does Registax at http://aberrator.astronomy.net/registax/index.html,
with the added advantage that it's free.

--
bp
Proud Member of the Human O-Ring Society Since 2003