ASTRO: Abell 2197 and UGC 10704 reprocessed

On 8/31/2011 7:26 PM, Skywise wrote:

Interesting. I put it on to Picasa and read it back with the same
lines. I put it a couple other places and again see lines.

Can you provide links to those locations? Then I (and others?)
can tell you if we see anything.

I took it off all sites when I replaced with the line-less images except
one that picks it up from USENET
http://www.spacebanter.com/attachmen...tid=3688&stc=1


Had another imager on
a different ISP look and he too saw the lines on the earlier versions.

What program are you using to create the final image? I'm wondering
if perhaps there's some problem in the JPG encoding for that image
that most viewer's software is able to get past, yet breaks in a few
viewer's whose software can't handle the error gracefully.

FITS files are imported into Photoshop CS using FITSLiberator. CS is
then used for all processing. Processing done in 16 bit TIFF mode then
converted to JPG for posting.

I'm no expert on image file formats, but for a personal programming
project I've been dabbling with the TIFF specification. I recall
references in the specs saying that the software needs to be able to
handle certain errors gracefully.

Perhaps the few of you who do see the lines are seeing an error in
the problem file's encoding not being handled gracefully by whatever
software you are using to view the image with.

I didn't see the lines until posted. They look fine on all my viewing
programs. Just the posted images that showed the lines. I'd have not
posted them if I saw lines.


Unfortunately, I have zero knowledge of the jpg specification,
although I may eventually as TIFF allows jpg compression, and is
included in an appendix. THat is, if I ever get finished with writing
that TIFF program.

OH... another thought just hit me. When you are viewing these images
and seeing the lines, are you viewing them at 100% scale? Not all
programs dither down the image when zoomed out. I've seen programs
that simply skip pixels/lines in order to shrink the viewed image
size, which then causes interesting artifacts such as moire and other
weirdness.

Brian

Yes I always view at 100%.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

OK, Rick, you took out all those theories pretty quickly.

Can you try making the jpg again from the final 16bit TIFF, which I
presume is your final product? I'd be curious if that version has
the same problem. Theoretically, if the source is the same, and the
encoding settings are the same, the two files should be byte-by-byte
identical. I actually already have a program which can test that,
which I wrote. Although, if you end up with two files with different
sizes you know right there they are not identical.

I don't know if I can find the answer, or help find it, but I love
a good technical mystery.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?

On 9/1/2011 1:54 AM, Skywise wrote:
OK, Rick, you took out all those theories pretty quickly.

Can you try making the jpg again from the final 16bit TIFF, which I
presume is your final product? I'd be curious if that version has
the same problem. Theoretically, if the source is the same, and the
encoding settings are the same, the two files should be byte-by-byte
identical. I actually already have a program which can test that,
which I wrote. Although, if you end up with two files with different
sizes you know right there they are not identical.

I don't know if I can find the answer, or help find it, but I love
a good technical mystery.

Brian

The Tiff files don't show the lines, nor do the JPG. Only the JPG after
posting show it. All JPGs were made from the same TIFF. I never redid
it. After converting to 8 bit I saved as a JPG which was fine until
posted then had lines at my end, not yours apparently. I smoothed the
background a bit and reposted (starting from the TIFF). Again the
lines. I tried again applying even more blurring of the background and
higher compression. That didn't show the lines.

You see the lines at the Space Banter link? I do on all 4 computers in
the house.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

Rick Johnson wrote in news:4e5f2e39$0$2966$a8266bb1
@newsreader.readnews.com:


You see the lines at the Space Banter link? I do on all 4 computers in
the house.

I do and I don't.

I followed the link and viewed the image in my browser (Firefox 3.5.6).
I could see the lines.

I then right clicked and copied the image, pasting it into an image
editor. In this case an old version of Paint Shop Pro on my older Win2k
system that is my "online computer". I could see the lines.

Then, I right clicked and saved the image to the hard drive. I viewed
that file in a thumbnail program and in this old PSP program. NO LINES
in either program.

What this tells me is that the browser is not decoding the image properly.
When I right click copied the image, all that's happening is the browser
is copying the decoded contents to the clipboard. The damage is already
done. When I right click save, it's saving the jpg file from it's cache.

As a further test, I actually fired up Internet Explorer (scary). This
is the old version 5 that installs with Win2k. I never use IE. Result
is NO LINES.

So here we have two browsers, side by side, one shows the lines, the
other doesn't. This is further evidence towards an encoding/decoding
problem.

Attached is a PNG image capture of both browsers together, along with
a histogram EQ'd version to show things easily.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?