GIMP

Troy Piggins wrote:

Dammit - forgot to change the Subject header.

shakes fist at Alan Browne /

Regrets, I'm not shaking. In PS, you can apply the sharpen to selected
area or the portions of an image in whatever layer(s) you choose.

It just works.


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Hanz wrote:
Alan Browne wrote:
Floyd L. Davidson wrote:
snip

The USM is ________HORRIBLE________

Actually, it's great.

No. In PS CS3, a very light touch USM on an area of fine detail
worked fine. Identical settings (emphasis is on _light_) in gimp on
the same image created halos as well as deepened blacks with blocking
up in shadow areas. This likely includes further artifacts from the
8b/color processing whereas in CS3 it is done at 16b/color.

Plain horrible.

With such wildly different opinions, I wonder what the differences in
the PS USM filter vs. the GIMP USM filter are. Does anyone know what
these filters *exactly* do, and in what respect they are different? At
least the controls seem to be the same, but perhaps the units differ.
-- Hans

Hmm. 1/ weight by percentage in PS or coeficient in Gimp. No difference
2/ radius by pixels in PS and Gimp
3/ threshold in both in "Levels" of dynamic

Pretty much the same inputs. What happens _in_ the filter should be the
same; but is not. And due to Gimps coarser internal data representation
of the image (at least when PS is in 16 b/c) it is pretty much
impossible for the result to be the same.

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Hanz wrote:
snipped

Not sure why you reposted all that w/o adding to it. But the plain fact
is this: where processing takes place with 8b/c v 16 b/c, successive
operations are definitely going to cause more damage to the coarser data
than to the finer data. That is why Gimp is compromised (We'll see how
well it does in the new version with real number ( 16 b/c) representation.)



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Alan Browne wrote:
Troy Piggins wrote:

Dammit - forgot to change the Subject header. shakes
fist at Alan Browne /

Regrets, I'm not shaking.

But you *are* sputtering.

In PS, you can apply the sharpen to selected
area or the portions of an image in whatever layer(s) you choose.

It just works.

That is *exactly* the same as GIMP.

Of course if you do know that then you are dishonest; if
you don't know that you shouldn't be commenting at all
on GIMP, as you clearly are not even basically familiar
with how it works or what it does.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Mark Thomas wrote:
Floyd L. Davidson wrote:
Hanz wrote:
With such wildly different opinions, I wonder what the differences in
the PS USM filter vs. the GIMP USM filter are. Does anyone know what
these filters *exactly* do, and in what respect they are different? At
least the controls seem to be the same, but perhaps the units differ.
-- Hans

Unsharp Mask is a generic technique, and does not in
itself imply a specific implementation algorithm. Hence
you are correct that the units differ. They usually
(but not always) have the same names, but that implies
the function not the magnitude.

In a bit of experimentation I just did, I found that I get an almost
exact equivalence to a fairly typical Photoshop USM of:
0.3/150%/3 (radius/amount/levels)
by setting the Gimp to use:
0.3/0.6/3 (radius/amount/threshhold)

I *guessed* (wrong) that would mean I could play with either the radius
or level(threshhold) while holding the amount steady and get similar
results, but it was not so. As a test, I left the settings as shown
above and then changed Photoshop's radius to 3.0 instead of 0.3. When I
did the same in Gimp, the results were dramatically different and I had
to ramp the amount slider right up to get anywhere near a match. Once I
had got a similar sharpening result the halos in Gimp were noticeably
wider.

So the three factors obviously interact quite differently in each
program - this doesn't necessarily mean anything good or bad, but it
does mean if you change from one to the other, you are going to have a
fair bit of re-learning/experimenting..

And I'm sorry, but for very subtle, low-level sharpening, I find the PS
controls/preview easier to use - in Gimp, the amount slider is way down
to the left for my sort of sharpening and small movements mean big
changes. I'm afraid my sharpening isn't that brutal...

Also, someone implied that Gimp toggled the preview on or off by simply
holding down the mouse or scroll bar..? not so in mine (2.4.6). You
need to check/uncheck the Preview box, and it only previews the effect
in the dialog box. In PS you merely have to hold the mouse button and
release it as you scroll around - nice.

Good comments.


--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: Remove FreeLunch.
-- usenet posts from gmail.com and googlemail.com are filtered out.

Alan Browne wrote:
Hanz wrote:
With such wildly different opinions, I wonder what the
differences in the PS USM filter vs. the GIMP USM
filter are. Does anyone know what these filters
*exactly* do, and in what respect they are different?
At least the controls seem to be the same, but perhaps
the units differ.
-- Hans

Hmm. 1/ weight by percentage in PS or coeficient in Gimp. No difference

Very different numbers.

2/ radius by pixels in PS and Gimp

Very different numbers.

3/ threshold in both in "Levels" of dynamic

What is that supposed to mean? "levels of dynamic"????

Pretty much the same inputs.

Quite different.

What happens _in_ the filter should be the
same; but is not.

There is no reason at all that they should be exactly the
same, or even close to the same.

And due to Gimps coarser internal data representation
of the image (at least when PS is in 16 b/c) it is pretty much
impossible for the result to be the same.

That is absurd!


Alan, why don't you just knock off this bit of
application bigotry that you insist on. There actually
are valid reasons to choose PS or GIMP, but your biases
are not valid.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Alan Browne wrote:
Hanz wrote:
snipped

Not sure why you reposted all that w/o adding to it. But the plain fact
is this: where processing takes place with 8b/c v 16 b/c, successive
operations are definitely going to cause more damage to the coarser data
than to the finer data. That is why Gimp is compromised (We'll see how

That is BS and simply is not true. The "successive
operations" are done with 32 bit integer arithmetic.

well it does in the new version with real number ( 16 b/c) representation.)

You can't even describe it properly. What does "real
number ( 16 b/c) representation.)" mean to you?

It will be with 8, 16 or 32 bit depth (integer) data.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

* Alan Browne wrote :
Troy Piggins wrote:

Dammit - forgot to change the Subject header.

shakes fist at Alan Browne /

Regrets, I'm not shaking.

You would if you saw how big and tough and hairy my fist was

In PS, you can apply the sharpen to selected area or the
portions of an image in whatever layer(s) you choose.

I'm sure you can. GIMP has layer masks too, so you can achieve
the same result with just a couple of clicks if you so desire.
But for me, the smart sharpen plugin works a treat.

It just works.

So does GIMP. I'm not bashing PS. I'm just pointing out that
almost everything PS does, GIMP does. And the gap between
functions is narrowing all the time.

I started using GIMP because it was free, and I use linux, and it
was plenty powerful for what I need to do. I have only been
using it for photo editing for under a year, and part time. I am
now completely comfortable using it, know my way around the
interface etc.

I tried helping my brother out with some editing on his computer
where he has one of the newer versions of PS, but he can't grasp
the concept of layers etc yet so I said I'd show him how to use
them. I was totally lost and couldn't find any of the commands
or tools I wanted other than the obvious basics.

So I guess from my perspective, PS had a totally unpleasant
interface and hard to find tools. I'm not actually saying that,
mind you, because I know it's not the case. It's just that I
haven't had or taken the time to sit down and try to use it.

If I'd tried the same thing in GIMP, I could have shown him in
seconds.

If I had bought PS in the first place, I'm sure I would think PS
was easier to use if I then tried to use GIMP second.

BTW, keep in mind I'm only an amatuer who takes photos as a
hobby, posts them on the internet, and if a shot or 2 come out
exceptionally well (rare event) might get it printed and hang on
the wall for a bit. If I was a professional, where I could write
off the cost of PS licences to the business etc, or if I could
just consider it a part of my equipment, my views might change
too. And I'd probably look closer at the colour depth etc if I
was printing for a living.

So basically, it's whatever you feel comfortable with I guess.
But I know I'd take the dollars saved on buying PS and put it
towards some new glass

--
Troy Piggins
I always appreciate critique.

Floyd L. Davidson wrote:
Mark Thomas wrote:
Also, someone implied that Gimp toggled the preview on or off by simply
holding down the mouse or scroll bar..? not so in mine (2.4.6). You
need to check/uncheck the Preview box, and it only previews the effect
in the dialog box. In PS you merely have to hold the mouse button and
release it as you scroll around - nice.

Just move the mouse slightly (which will scroll the preview within the
image). You are describing for PS exactly what GIMP does.


No, it isn't. Because AS SOON AS Gimp recalculates the image it
replaces it - you do NOT control the re-appearance of the sharpened
image. Maybe that gives you time on a slow machine, but on mine it
means I am continually clicking and re-moving - that is not the same at
all, and is annoying.

In article , Troy Piggins
wrote:

So does GIMP. I'm not bashing PS. I'm just pointing out that
almost everything PS does, GIMP does. And the gap between
functions is narrowing all the time.

that's not even remotely close to being true. photoshop does a *lot*
more than the gimp and the gap is *growing*, not shrinking. people who
think that the gimp is essentially a free version of photoshop are
simply unfamiliar of what photoshop can actually *do*. and it's not
just a feature checklist; as i said before, there are a lot of little
things that make working in photoshop more productive.