best way to enlarge astro images?

I'm caught between a rock and a hard place. I have some fairly small DSO
images that I want to enlarge by 40-60%. Normally, I just do a bicubic
enlargement in Photoshop, but the image always seems blurrier. And, of
course, if you add sharpening before enlarging, noise rears its ugly head.
So, is there any way I can enlarge up to 70% and get the best possible image
quality in the end without the noticeable blurriness?

Thanks,
JW

Neat Image is very good at removing noise. I recommend you try the demo
version.

JW Walters wrote:
I'm caught between a rock and a hard place. I have some fairly small
DSO
images that I want to enlarge by 40-60%. Normally, I just do a
bicubic
enlargement in Photoshop, but the image always seems blurrier. And,
of
course, if you add sharpening before enlarging, noise rears its ugly
head.
So, is there any way I can enlarge up to 70% and get the best
possible image
quality in the end without the noticeable blurriness?

Thanks,
JW

JW Walters:
I'm caught between a rock and a hard place.

Precisely.

I have some fairly small DSO
images that I want to enlarge by 40-60%. Normally, I just do a bicubic
enlargement in Photoshop, but the image always seems blurrier. And, of
course, if you add sharpening before enlarging, noise rears its ugly head.

Precisely. But it is best to sharpen after enlarging; indeed, it is a
good rule of thumb to make sharpening the very last thing you do to an
image in Photoshop. Have you tried "true" unsharp masking, i.e.,
applying a blurred copy of an image to itself? This sometimes helps.

So, is there any way I can enlarge up to 70% and get the best possible image
quality in the end without the noticeable blurriness?

Not really. I've tried a number of utilities and Photoshop filters, but
they all introduce noise or they introduce noise and then attempt to
mask it by blurring the image. Since I'm a print graphics guy who likes
nice, sharp images, the software I've seen always disappoints. I can
only assume that those who praise this software have less stringent
requirements than I have. (Nothing wrong with that, mind you.)

The issue, of course, is that there is no such thing as a free lunch.

The result is that I almost never enlarge photos, but when I must, I
use Photoshop's bicubic enlargement and then I do considerable fussing
over the result until I get something that I consider an acceptable
compromise. I'm never completely happy with the result, but if an image
just has to be enlarged I will rationalize and say that it is "good
enough."

Davoud

"Davoud" wrote in message
...
JW Walters:
I'm caught between a rock and a hard place.

Precisely.

I have some fairly small DSO
images that I want to enlarge by 40-60%. Normally, I just do a bicubic
enlargement in Photoshop, but the image always seems blurrier. And, of
course, if you add sharpening before enlarging, noise rears its ugly
head.

Precisely. But it is best to sharpen after enlarging; indeed, it is a
good rule of thumb to make sharpening the very last thing you do to an
image in Photoshop. Have you tried "true" unsharp masking, i.e.,
applying a blurred copy of an image to itself? This sometimes helps.

So, is there any way I can enlarge up to 70% and get the best possible
image
quality in the end without the noticeable blurriness?

Not really. I've tried a number of utilities and Photoshop filters, but
they all introduce noise or they introduce noise and then attempt to
mask it by blurring the image. Since I'm a print graphics guy who likes
nice, sharp images, the software I've seen always disappoints. I can
only assume that those who praise this software have less stringent
requirements than I have. (Nothing wrong with that, mind you.)

The issue, of course, is that there is no such thing as a free lunch.

The result is that I almost never enlarge photos, but when I must, I
use Photoshop's bicubic enlargement and then I do considerable fussing
over the result until I get something that I consider an acceptable
compromise. I'm never completely happy with the result, but if an image
just has to be enlarged I will rationalize and say that it is "good
enough."

When you said you are a "print graphics guy" you struck a cord because that
is precisely the reasoning behind my initial question. I hate how most
images I produce look in print and for various reasons, the monitor just
doesn't bring out all those little things that can spoil the image like a
print can. Most DSOs I produce must be enlarged quite a lot to even fit a
3x5 print. This almost always gives a large, blurrier result and I have to
tweak the heck out of it, the larger I have to enlarge if I want the print
to be acceptable.

Well, unless someone else chimes in with a viable alternative, looks like
I'll continue with my current process, which takes a great deal of time! At
one point, I had tried a program called S-spline, which is supposed to be
great for enlargements, but it's so easy to intoduce artifacts that I just
stuck with standard bicubic instead.

JW

Davoud

"gubbenimanen" wrote in message
oups.com...
Neat Image is very good at removing noise. I recommend you try the demo
version.

Thanks, but been there, done that. Even using a calibrated noise print, it
smooths the prints too much and leaves artifacts even if I sharpen a little.
I use it for web images, but that's about all. Prints, for some reason, are
a whole other matter when it comes to the nearly invisible errors of web
images.

JW

JW Walters wrote:
I'm caught between a rock and a hard place. I have some fairly small
DSO
images that I want to enlarge by 40-60%. Normally, I just do a
bicubic
enlargement in Photoshop, but the image always seems blurrier. And,
of
course, if you add sharpening before enlarging, noise rears its ugly
head.
So, is there any way I can enlarge up to 70% and get the best
possible image
quality in the end without the noticeable blurriness?

Thanks,
JW

There is a trick I learned from a professional photographer that I use with
my astro images. If you increase the size of the picture no more than 10%
then the image retains its sharpness and detail (Image/image size/document
size/percentage...110% then press enter... it is one of those mysteries
about Photoshop). To get to 70%, or any number, just keep adding 110% to
the document size until you achieve the dimensions that you want. It works.

Lloyd


"JW Walters" wrote in message
nk.net...
I'm caught between a rock and a hard place. I have some fairly small DSO
images that I want to enlarge by 40-60%. Normally, I just do a bicubic
enlargement in Photoshop, but the image always seems blurrier. And, of
course, if you add sharpening before enlarging, noise rears its ugly head.
So, is there any way I can enlarge up to 70% and get the best possible
image
quality in the end without the noticeable blurriness?

Thanks,
JW

On Mon, 07 Feb 2005 22:43:42 GMT, "JW Walters" wrote:

I'm caught between a rock and a hard place. I have some fairly small DSO
images that I want to enlarge by 40-60%. Normally, I just do a bicubic
enlargement in Photoshop, but the image always seems blurrier. And, of
course, if you add sharpening before enlarging, noise rears its ugly head.
So, is there any way I can enlarge up to 70% and get the best possible image
quality in the end without the noticeable blurriness?

There is only so much information in the DSO that you can record.
Regardless of the size of the detector, if your camera and telescope are
reasonably matched, your true resolution is only on the order of an
arcsecond per pixel, give or take. So when you enlarge your image, you
would expect it to get blurrier- just as if you operated your telescope
at a higher magnification.

I image with an ST8i, usually binned 2x2. That gives me images that are
765x510. I upsample these by 2, using Photoshop's bicubic smoother mode,
and print 8x10s at 150 dpi. I find the results very acceptable. You
shouldn't see any noticeable pixelation, but if you do consider applying
a very slight Gaussian blur. It's counterintuitive, but you may find
that it actually makes the final image appear sharper.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

JW Walters wrote:
Well, unless someone else chimes in with a viable alternative, looks like
I'll continue with my current process, which takes a great deal of time! At
one point, I had tried a program called S-spline, which is supposed to be
great for enlargements, but it's so easy to intoduce artifacts that I just
stuck with standard bicubic instead.


You *can't* enlarge an image without blurring or other artifacts. You
only have the signal captured in the starting image, and that's that.
All those extra pixels can only be guessed at. And if your starting
image has already been compressed by some lossy, distorting method, like
jpeg, then its going to much worse much faster.

Your only real hope is to get the biggest, cleanest copy of the original
you can, and be prepared for some editing.

And the monitor vs printer differences? If you are using Photoshop, you
can calibrate it against both your monitor and your printer, and then
you will be able to get what-you-see-is-what-you-print. If you don't
calibrate them, then you're just guessing, and its going to be hit or
miss all the time.

On 07 Feb 2005 22:59:52 EST, "Lloyd Bentsen" wrote:

There is a trick I learned from a professional photographer that I use with
my astro images. If you increase the size of the picture no more than 10%
then the image retains its sharpness and detail (Image/image size/document
size/percentage...110% then press enter... it is one of those mysteries
about Photoshop). To get to 70%, or any number, just keep adding 110% to
the document size until you achieve the dimensions that you want. It works.

I've heard about that trick, too. But I've got to say, after trying it
on a lot of different images from conventional to astronomical (and some
resolution test charts, too), the result is inevitably worse than a
single, simple bicubic resample.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

I copied this from the read me file of a new program I have, haven't tried
it yet but it may be what you are looking for.

Clear Pix,

CraigW

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"JW Walters" wrote in message
nk.net...
I'm caught between a rock and a hard place. I have some fairly small DSO
images that I want to enlarge by 40-60%. Normally, I just do a bicubic
enlargement in Photoshop, but the image always seems blurrier. And, of
course, if you add sharpening before enlarging, noise rears its ugly head.
So, is there any way I can enlarge up to 70% and get the best possible
image
quality in the end without the noticeable blurriness?

Thanks,
JW