Lenses and sharpening

In article , PeterN
wrote:

I gaae him some common uses. He typically uses "edge case' to give him
wriggle room.

wrong again.

what i call an edge case is an edge case and what you're calling common
can be done *without* lab more easily and with better quality results.

in other words, you're blaming others for your own lack of knowledge
and unwillingness to learn.

Well then explain with facts and detail.
Warning. I have Dan's book and will use it as a reference.

that's your problem. dan is wrong and reading his books has led you
astray.

if you read other books, you'll see that they consistently prove just
how much of an idiot dan really is. i've mentioned two such books in
this thread and other books in other threads.

The procedures in his book work just fine for me, and others.
http://www.dgrin.com/showthread.php?t=18308

I presented proof. As usual, you have presented nothing.
You want to persist., go argue with yourself.

you provided your personal preference, not proof.

In article , PeterN
wrote:

However, LAB is great for color changes that maintain subtle
tonality. e.g channel swapping.

you must be kidding.

Why?

channel swapping is hardly subtle, *especially* in lab.

Who said channel swapping was subtle.

you did.

Where? Show thee message #.

you must be kidding.

On Tue, 07 Oct 2014 17:26:29 -0400, nospam
wrote:

In article , PeterN
wrote:

For
some reason the conversion of RGB -- Lab has been particularly
singled out for criticism in this respect.

it's a bad workflow because what can be done with an rgb-lab-rgb
conversion can be done *without* the conversion and with better
results.

Yes it can be done in RGB, but with a lot more effort.

nope. it's less effort and with higher quality results in rgb since you
don't need to make two lossy conversions. it's also quicker.

The conversions are not significantly lossy: certainly not in
comparison with the changes you are about to wreak on the image.
As te whether or not it's quicker: it maybe, but it depends on what
you are trying to achieve.

Take a simple example stock photo and change the color in RGB, and then
make the same color change in LAB.

that's meaningless. change the colour to what?

Or, simply increase color saturation n RGB and make the same change in LAB.

there is absolutely *no* need to go to lab to change saturation.

All yo do is sout questionable theory. Show some real life proof.

there's nothing questionable about it.

read something *other* than the crap marguilis spouts and learn
something new for once.
--

Regards,

Eric Stevens

On Tue, 07 Oct 2014 17:26:25 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

But if one went to Lab space and back along the way, then it will always
be lossy even if nothing was done in Lab space.

True, but as I found in my experiments (as described again, below) the
loss on conversion is close to zero. The argument is not whether or
not there is any loss in going through Lab space but whether or not
the loss is significant. nospam seems to equate even the smallest loss
arising from Lab conversion as significant

once again, i never said it was significant. i said it's lossy and it
is.

stop lying about what i say, but at least you finally agree.

but he forgets that the
fact that he has loaded the image into an editor is going to wreak
considerably more damage to the original image.

not necessarily.

Of course you are!

However the point is that your intention is that the damaged image
will be more likeable than the original.

That's why I think he
is talking nondense when he advocates not using Lab so as to avoid
damage.

there is absolutely no reason whatsoever to use lab because just about
everything you can do in lab can be done without a lab conversion *and*
avoid the losses.

if you apply the same logic, shooting entirely in jpeg is the way to go
because ultimately, the image will be a jpeg anyway.

Not if I produce it. All my really worthwhile prints finish up as
TIFF.
--

Regards,

Eric Stevens

On Tue, 07 Oct 2014 17:26:23 -0400, nospam
wrote:

In article , Sandman
wrote:

Martin Brown:
Since CIELAB is a colour space intended to manage just noticeably
colour differences more optimally than the naive RGB colour space
it isn't too surprising that you cannot *see* a difference in the
final JPG taken from RGB or via CIELAB. But they are very slightly
different.

Agreed, but the question is, does the difference matter?

That wasn't, however, "the question", Eric. You quote Dan saying this:

"RGBLABRGB is damage free"

That is an incorrect statement, which nospam has corrected. That is all.

yep.

But you are also arguing that the damage is such that conversions to
Lab should be completely avoided. You are heaping abuse on Dan
Margulis who teaches how to use Lab. You are not just arguing that Lab
conversions cause damage (no matter how infinitesmal that damage may
be). You *hate* the idea of Lab conversion and froth at the mouth when
the possibility is mentioned. Your opposition to Lab is totally
irrational.
--

Regards,

Eric Stevens

On Tue, 07 Oct 2014 17:26:24 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

In the context of the present discussion, the question is, does the
conversion to Lab colour incur any more damage than one can expect in
the course of ordinary editing? My understanding of nospam's claim is
that it does. My (admittedly limited) experience with it suggests that
conversion to Lab causes no significant damage; certainly less than I
am going to inflict on the image by the changes I want to make.

Since CIELAB is a colour space intended to manage just noticeably colour
differences more optimally than the naive RGB colour space it isn't too
surprising that you cannot *see* a difference in the final JPG taken
from RGB or via CIELAB. But they are very slightly different.

Agreed, but the question is, does the difference matter? In particular
does it matter enough to earn the reputation that nospam is trying to
assign to it? I would generally answer 'no' to both of thos questions.

then you should shoot entirely in jpeg and keep all your audio in mp3,
because the difference doesn't matter.

there will be 'more damage' from the inaccuracies of the display and
amplifier and speakers or headphones.

The extent of the damage is not at all comparable.
--

Regards,

Eric Stevens

On 10/7/2014 5:26 PM, nospam wrote:
In article , PeterN
wrote:

For
some reason the conversion of RGB -- Lab has been particularly
singled out for criticism in this respect.

it's a bad workflow because what can be done with an rgb-lab-rgb
conversion can be done *without* the conversion and with better
results.

Yes it can be done in RGB, but with a lot more effort.

nope. it's less effort and with higher quality results in rgb since you
don't need to make two lossy conversions. it's also quicker.

Take a simple example stock photo and change the color in RGB, and then
make the same color change in LAB.

that's meaningless. change the colour to what?

e.g. yellow to blue


Or, simply increase color saturation n RGB and make the same change in LAB.

there is absolutely *no* need to go to lab to change saturation.

If you had any good faith you would not say that. I posted a link, that
says just the opposite, that you didn't read.


All yo do is sout questionable theory. Show some real life proof.

there's nothing questionable about it.

read something *other* than the crap marguilis spouts and learn
something new for once.



--
PeterN

On 08/10/2014 00:17, Eric Stevens wrote:
On Tue, 07 Oct 2014 17:26:23 -0400, nospam
wrote:

In article , Sandman
wrote:

Martin Brown:
Since CIELAB is a colour space intended to manage just noticeably
colour differences more optimally than the naive RGB colour space
it isn't too surprising that you cannot *see* a difference in the
final JPG taken from RGB or via CIELAB. But they are very slightly
different.

Agreed, but the question is, does the difference matter?

That wasn't, however, "the question", Eric. You quote Dan saying this:

"RGBLABRGB is damage free"

That is an incorrect statement, which nospam has corrected. That is all.

It does depend here rather critically on what you mean by damage free.

If you mean is it strictly lossless then the answer is no, but if you
mean can you actually *see* the difference between them then the answer
is yes. You would get a *much* larger image content variation if you had
delayed pressing the shutter release by 1us.

Naive RGB has far too many irrelevant shades of not quite green. They
are all numerically distinct but the human eye cannot tell them apart.

http://en.wikipedia.org/wiki/Color_difference#Tolerance

yep.

But you are also arguing that the damage is such that conversions to
Lab should be completely avoided. You are heaping abuse on Dan
Margulis who teaches how to use Lab. You are not just arguing that Lab
conversions cause damage (no matter how infinitesmal that damage may
be). You *hate* the idea of Lab conversion and froth at the mouth when
the possibility is mentioned. Your opposition to Lab is totally
irrational.


Why does that surprise you?

It is typical nospam sophistry.

--
Regards,
Martin Brown

On 10/7/2014 5:26 PM, nospam wrote:
In article , PeterN
wrote:

You have never noticed the ease of a color change in LAB, compared to
making a similar color change in RGB.

YOu have never brought out color using LAB that could not easily be
brought out in RGB.

nonsense.

you just don't know how to do it in rgb.

Well let's see a FACTUAL comparison.

read the books i've already mentioned.

you won't, because you only want to argue.

Show some proof. As I said earlier, I just want to keep people from
believing your nonsense.

read the books. they go into vastly more detail than i care to.

You have never proven a thing, except yur favorite line.

i don't need to prove 2=2.


IOW you don't understand WTF you are babbeling about

--
PeterN

On 10/7/2014 5:26 PM, nospam wrote:
In article , PeterN
wrote:

I gaae him some common uses. He typically uses "edge case' to give him
wriggle room.

wrong again.

what i call an edge case is an edge case and what you're calling common
can be done *without* lab more easily and with better quality results.

in other words, you're blaming others for your own lack of knowledge
and unwillingness to learn.

Well then explain with facts and detail.
Warning. I have Dan's book and will use it as a reference.

that's your problem. dan is wrong and reading his books has led you
astray.

if you read other books, you'll see that they consistently prove just
how much of an idiot dan really is. i've mentioned two such books in
this thread and other books in other threads.

The procedures in his book work just fine for me, and others.
http://www.dgrin.com/showthread.php?t=18308

I presented proof. As usual, you have presented nothing.
You want to persist., go argue with yourself.

you provided your personal preference, not proof.


If you bothered to read, which I doubt, you would haves seen duplcable
procedures where LAB is better for saturation control, and why.


--
PeterN