Computer Graphics with Photoshop - Is Adobe Gamma appropriate for TFTs?

Author

Is Adobe Gamma appropriate for TFTs?

Gary

2004-01-23, 12:28 pm

I heard that Adobe Gamma was specifically for "tubes". Is this so? If so,
what else can we calibrate our moitors with? Before the flames start, I
already tried a banana and the top of a pepsi bottle.

Gary

Mike Russell

2004-01-23, 7:28 pm

Gary wrote:

quote:

> I heard that Adobe Gamma was specifically for "tubes". Is this so?
> If so, what else can we calibrate our moitors with?

Adobe Gamma is a working space - which means it is a storage, not a display
specification.

Calibration is done using Adobe Gamma, and the resulting profile is saved
for later use by Photoshop and other color aware Adobe apps. For this
procedure you may use any working profile you wish, typically the choices
are Adobe Gamma, sRGB, Colormatch, and Apple RGB.

The first two working spaces are typically used on Windows, and the last two
on the Macintosh because the overall brightness (gamma) of those workspaces
looks good on the monitors of the respective systems.

I use sRGB as my working space because Adobe RGB images appear drab when
viewed outside of Photoshop. Others choose Adobe RGB, and their reasons
include the wider gamut of that color space, and they are less concerned
about how their images might appear to less initiated people.

quote:

> Before the
> flames start, I already tried a banana and the top of a pepsi bottle.

But do they have aluminum foil hats on? :-)
--

Mike Russell
www.curvemeister.com
www.geigy.2y.net

Bill Hilton

2004-01-23, 7:28 pm

It sure sounds like Mike is confusing "Adobe Gamma" (the monitor calibration
utility) with "Adobe RGB" (the working space) ... think about it.

Bill

quote:

[QUOTE][color=darkred]
>From: "Mike Russell" REgeigyMOVE@pacbellTHIS.net
>
>Adobe Gamma is a working space - which means it is a storage, not a display
>specification.

Greg

2004-01-23, 8:28 pm

"Gary" <gary.sandy@btinternet.com> wrote in message
news:buri43$fp5$1@titan.btinternet.com...

quote:

> I heard that Adobe Gamma was specifically for "tubes". Is this so? If

so,

quote:

> what else can we calibrate our moitors with? Before the flames start, I
> already tried a banana and the top of a pepsi bottle.

That's my understanding too. I don't know of any utility like Adobe Gamma
which is designed to work
with TFTs, and I'd be interested if there is something available. I have
read that TFTs can often have an
"S" response, and that's part of the reason why Adobe Gamma won't work well.
I do wonder
though whether modern TFTs might be better behaved, and be more linear in
their native response?

You probably know this already, but you can use a calibration package which
is specifically designed
to work with TFTs. (Eye One Display, Spyder, etc)

Greg.

Flycaster

2004-01-23, 10:28 pm

"Mike Russell" <REgeigyMOVE@pacbellTHIS.net> wrote in message
news:xNhQb.16428$hm3.11178@newssvr25.news.prodigy.com...

quote:

> Adobe Gamma is a working space - which means it is a storage, not a

display

quote:

> specification.

[snip]

quote:

>For this
> procedure you may use any working profile you wish, typically the choices
> are Adobe Gamma, sRGB, Colormatch, and Apple RGB.

Anybody else want to step in and help the Curvemeister learn the difference
between Adobe Gamma, working spaces and profiles?

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Greg

2004-01-23, 10:28 pm

"Flycaster" <noyb@nospam.com> wrote in message
news:4011d165$1_1@corp.newsgroups.com...

quote:

> Anybody else want to step in and help the Curvemeister learn the

difference

quote:

> between Adobe Gamma, working spaces and profiles?

I reckon someone else was at his keyboard, playing a trick on him. :)

Greg.

Mike Russell

2004-01-23, 11:28 pm

Bill is correct, and not for the first time. - Adobe RGB is a working space,
Adobe Gamma is the utility for setting up your monitor and it's working
space.
--

Mike Russell
www.curvemeister.com
www.geigy.2y.net

Bill Hilton wrote:[QUOTE][color=darkred]
> It sure sounds like Mike is confusing "Adobe Gamma" (the monitor
> calibration utility) with "Adobe RGB" (the working space) ... think
> about it.
>
> Bill
>
>

Graeme Cogger

2004-01-24, 2:28 pm

In article <4011d165$1_1@corp.newsgroups.com>, noyb@nospam.com
says...

quote:

> "Mike Russell" <REgeigyMOVE@pacbellTHIS.net> wrote in message
> news:xNhQb.16428$hm3.11178@newssvr25.news.prodigy.com...
>
> Anybody else want to step in and help the Curvemeister learn the difference
> between Adobe Gamma, working spaces and profiles?
>

In simple terms, and probably not 100% accurate (please correct
me where necessary!):
A profile (specifically an ICC profile) is a set of information
that describes the colour characteristics of a device or a
working space, relative to a theoretical absolute (e.g. LAB
colour space). The term 'colour space' is also often used to
describe this colour information. All profiles contain a
subset of all possible colours from LAB space. If it contains
a fairly large subset it is a wide colour gamut.
For a scanner or digicam, the profile describes what absolute
(e.g. LAB) colour is represented by each set of RGB values
produced by the device.
For a monitor, the profile describes what absolute (e.g. LAB)
colour it will display for each value set of RGB values it is
given.
For a printer, the profile describes what absolute (e.g. LAB)
colour it will print for each value set of RGB values it is
given.

A working space is the profile assigned to an image while you
work on it. It is not strictly needed, but is useful. For
example - if the image was edited in, say, the scanner profile
you would find that equal values of R, G and B did not
represent a neutral colour, making tools like the eyedropper in
'Levels' almost useless. Working space profiles are well
behaved (equal RGB values are always neutral) and have a
defined white point (e.g. what LAB colour is 255,255,255),
normally described as a temperature (e.g. 5000K). Typical
working profiles are Adobe RGB (fairly wide gamut) and sRGB
(rather narrower).

Adobe Gamma is an application. It lets you calibrate a monitor
by you setting the brightness, contrast, etc., and by loading a
colour LookUp Table (LUT) to the graphics card on startup. It
also creates a monitor profile to describe the calibrated
monitor and sets that profile as the default for your monitor.
Photoshop will automatically use this default monitor profile
to compensate the RGB values it sends to the graphics card, in
order that you see the correct colours for the profile (working
space) of the image.

Phew... HTH :-)

Flycaster

2004-01-24, 5:28 pm

"Graeme Cogger" <gcogger@bigSPAMfoot.com> wrote in message
news:4012b7fe$0$13351$cc9e4d1f@news-text.dial.pipex.com...

quote:

> In article <4011d165$1_1@corp.newsgroups.com>, noyb@nospam.com
> says...
difference[QUOTE][color=darkred]
>
> In simple terms, and probably not 100% accurate (please correct
> me where necessary!):
> A profile (specifically an ICC profile) is a set of information
> that describes the colour characteristics of a device or a
> working space, relative to a theoretical absolute (e.g. LAB
> colour space). The term 'colour space' is also often used to
> describe this colour information. All profiles contain a
> subset of all possible colours from LAB space. If it contains
> a fairly large subset it is a wide colour gamut.
> For a scanner or digicam, the profile describes what absolute
> (e.g. LAB) colour is represented by each set of RGB values
> produced by the device.
> For a monitor, the profile describes what absolute (e.g. LAB)
> colour it will display for each value set of RGB values it is
> given.
> For a printer, the profile describes what absolute (e.g. LAB)
> colour it will print for each value set of RGB values it is
> given.
>
> A working space is the profile assigned to an image while you
> work on it. It is not strictly needed, but is useful. For
> example - if the image was edited in, say, the scanner profile
> you would find that equal values of R, G and B did not
> represent a neutral colour, making tools like the eyedropper in
> 'Levels' almost useless. Working space profiles are well
> behaved (equal RGB values are always neutral) and have a
> defined white point (e.g. what LAB colour is 255,255,255),
> normally described as a temperature (e.g. 5000K). Typical
> working profiles are Adobe RGB (fairly wide gamut) and sRGB
> (rather narrower).
>
> Adobe Gamma is an application. It lets you calibrate a monitor
> by you setting the brightness, contrast, etc., and by loading a
> colour LookUp Table (LUT) to the graphics card on startup. It
> also creates a monitor profile to describe the calibrated
> monitor and sets that profile as the default for your monitor.
> Photoshop will automatically use this default monitor profile
> to compensate the RGB values it sends to the graphics card, in
> order that you see the correct colours for the profile (working
> space) of the image.
>
> Phew... HTH :-)

You know your stuff. Great job, and I look forward to seeing more of your
posts.

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Linelle Lane

2004-01-24, 6:28 pm

Like a previous poster, I struggle with the color space/profile/calibration
concept. From 1) a digital camera or scanner, to 2) Photoshop (as presented
by a monitor), to 3) a printer. And then there's "proof setup." Which of
these should be considered the starting place, or driving force?

"Graeme Cogger" <gcogger@bigSPAMfoot.com> wrote in message
news:4012b7fe$0$13351$cc9e4d1f@news-text.dial.pipex.com...

quote:

> In simple terms, and probably not 100% accurate (please correct
> me where necessary!):
> A profile (specifically an ICC profile) is a set of information
> that describes the colour characteristics of a device or a
> working space, relative to a theoretical absolute (e.g. LAB
> colour space). The term 'colour space' is also often used to
> describe this colour information. All profiles contain a
> subset of all possible colours from LAB space. If it contains
> a fairly large subset it is a wide colour gamut.
> For a scanner or digicam, the profile describes what absolute
> (e.g. LAB) colour is represented by each set of RGB values
> produced by the device.
> For a monitor, the profile describes what absolute (e.g. LAB)
> colour it will display for each value set of RGB values it is
> given.
> For a printer, the profile describes what absolute (e.g. LAB)
> colour it will print for each value set of RGB values it is
> given.
>
> A working space is the profile assigned to an image while you
> work on it. It is not strictly needed, but is useful. For
> example - if the image was edited in, say, the scanner profile
> you would find that equal values of R, G and B did not
> represent a neutral colour, making tools like the eyedropper in
> 'Levels' almost useless. Working space profiles are well
> behaved (equal RGB values are always neutral) and have a
> defined white point (e.g. what LAB colour is 255,255,255),
> normally described as a temperature (e.g. 5000K). Typical
> working profiles are Adobe RGB (fairly wide gamut) and sRGB
> (rather narrower).
>
> Adobe Gamma is an application. It lets you calibrate a monitor
> by you setting the brightness, contrast, etc., and by loading a
> colour LookUp Table (LUT) to the graphics card on startup. It
> also creates a monitor profile to describe the calibrated
> monitor and sets that profile as the default for your monitor.
> Photoshop will automatically use this default monitor profile
> to compensate the RGB values it sends to the graphics card, in
> order that you see the correct colours for the profile (working
> space) of the image.
>
> Phew... HTH :-)

Mike Russell

2004-01-24, 7:28 pm

Linelle Lane wrote:

quote:

> Like a previous poster, I struggle with the color
> space/profile/calibration concept. From 1) a digital camera or
> scanner, to 2) Photoshop (as presented by a monitor), to 3) a
> printer. And then there's "proof setup." Which of these should be
> considered the starting place, or driving force?

A lot of people find the concepts elusive, and with good reason (even
without people like me posting typographical errors on the subject :-).
There are several variables that can be changed, and a large quantity of
products and suggestions on what to change to get better color.

A simpler solution, that I recommend for those just starting out, is to set
your working space to sRGB, and print to your printer using a generic sRGB
driver setting, which is available with most printers. With my Epson 1270,
I use PhotoEhhance4 and get excellent results - better than any of the
profiles I have tried.

One of the better summaries of how to correctly configure Photoshop with
profiles, from a photographer's point of view, can be found on Ian Lyon's
web page:

http://www.computer-darkroom.com/ps7-colour/ps7_1.htm

The above link is for PS7, and there are additional links for PS6 and CS,
and a large number of other thoughtful articles. Ian also has some good
quality profiles for certain Epson printers.

I would recommend you get the simpler sRGB config set up first, and then,
provided you see any problems with the results, change things one at a time
to get closer to the profile based setup documented on Ian's page.

--

Mike Russell
www.curvemeister.com
www.geigy.2y.net

Jeffrey

2004-01-24, 8:28 pm

The rest of the posts on this thread, have gone off to discuss colour space,
I would however be interest in an answer to the original question, about the
relevance of the gamma function to TFT's displays.

Jeffrey
"Gary" <gary.sandy@btinternet.com> wrote in message
news:buri43$fp5$1@titan.btinternet.com...

quote:

> I heard that Adobe Gamma was specifically for "tubes". Is this so? If

so,

quote:

> what else can we calibrate our moitors with? Before the flames start, I
> already tried a banana and the top of a pepsi bottle.
>
> Gary
>
>

Flycaster

2004-01-24, 9:28 pm

"Jeffrey" <nospam@nospam.com> wrote in message
news:40130c3b$0$26115$afc38c87@news.optusnet.com.au...

quote:

> The rest of the posts on this thread, have gone off to discuss colour

space,

quote:

> I would however be interest in an answer to the original question, about

the

quote:

> relevance of the gamma function to TFT's displays.

Well, I may have been one of the guilty parties. Here's what I know (based
on personal experience):
I have yet to see a TFT that can be accurately calibrated for decent color
and contrast, irrespective of using Adobe Gamma, or a puck based system. To
be sure, I have not seen, much less tried to calibrate one new high-end (as
in $$$) LCD's or newer high-end laptop TFT displays. Some folks that have
seen them say they work great, others say differently.

All I can say is my laptop (a year old Dell 8100) is completely *useless*
for accurate image manipulation, other than by-the-numbers (for those of you
who remember 4.0, you'll know what I talk about). It does, however, work
great for storage and simple batch work that ultimately saves me a bunch of
time later once I return from a trip.

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Jeffrey

2004-01-24, 9:28 pm

ta, thanks for your reply.

I have a Toshiba Sattleite Pro 6100, while it gives pretty good colour and
is handy as you suggest for portable data holding, the quick edit/check, I
have not much confidence about colour matching or even gamma correction,
partcularly when the colour seems to change depending upon the angle you
looking at it.

Jeffrey
"Flycaster" <noyb@nospam.com> wrote in message
news:4013161e$1_1@corp.newsgroups.com...

quote:

> "Jeffrey" <nospam@nospam.com> wrote in message
> news:40130c3b$0$26115$afc38c87@news.optusnet.com.au...
> space,
> the
>
> Well, I may have been one of the guilty parties. Here's what I know

(based

quote:

> on personal experience):
> I have yet to see a TFT that can be accurately calibrated for decent color
> and contrast, irrespective of using Adobe Gamma, or a puck based system.

quote:

> be sure, I have not seen, much less tried to calibrate one new high-end

(as

quote:

> in $$$) LCD's or newer high-end laptop TFT displays. Some folks that have
> seen them say they work great, others say differently.
>
> All I can say is my laptop (a year old Dell 8100) is completely *useless*
> for accurate image manipulation, other than by-the-numbers (for those of

you

quote:

> who remember 4.0, you'll know what I talk about). It does, however, work
> great for storage and simple batch work that ultimately saves me a bunch

quote:

> time later once I return from a trip.
>
>
>
>
> -----= Posted via mcse.ms, Uncensored Usenet News =-----
> http://www.mcse.ms - The #1 Newsgroup Service in the World!
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Graeme Cogger

2004-01-24, 10:28 pm

In article <_YCQb.15446$IN7.1713@newssvr27.news.prodigy.com>,
REgeigyMOVE@pacbellTHIS.net says...

quote:

> Linelle Lane wrote:
>
> A lot of people find the concepts elusive, and with good reason (even
> without people like me posting typographical errors on the subject :-).
> There are several variables that can be changed, and a large quantity of
> products and suggestions on what to change to get better color.
>

I couldn't agree more - it is very confusing and I can't help
but feel there must be a simpler way of doing things. It's
also worth noting that 'good practice' can't really be
introduced in stages. Until at least the monitor and printer
are calibrated/profiled properly, changing to the 'correct' way
of doing things is just as likely to make things worse as it is
better.

<snip>

quote:

>
> I would recommend you get the simpler sRGB config set up first, and then,
> provided you see any problems with the results, change things one at a time
> to get closer to the profile based setup documented on Ian's page.
>

Good advice. I'd make sure you have at least a decent monitor
and printer/paper/ink profile before making any changes.

Graeme Cogger

2004-01-24, 10:28 pm

In article <40130c3b$0$26115$afc38c87@news.optusnet.com.au>,
nospam@nospam.com says...

quote:

> The rest of the posts on this thread, have gone off to discuss colour space,
> I would however be interest in an answer to the original question, about the
> relevance of the gamma function to TFT's displays.
>
> Jeffrey

Adobe Gamma does not generally work well with TFT monitors,
although it wasn't too bad on my Sharp LL-T1620 so it's worth a
try. There are various 'cheap' calibration systems available
that manage TFT's pretty well, but they cost around $200 or
more.

Thomas Madsen

2004-01-24, 10:28 pm

Greg wrote:

quote:

> I have read that TFTs can often have an "S" response, and that's
> part of the reason why Adobe Gamma won't work well.

I don't see an "S" response on my TFT but I'm definitely not
seeing a linear tone response either. No monitor has a linear
tone response, as far as I know.

quote:

> I do wonder though whether modern TFTs might be better behaved,
> and be more linear in their native response?

I can only speak for myself of course, but I've been using a TFT
as my primary monitor for the last 5 or 6 months or so, and I'm
never going back to a CRT again. I do have a CRT monitor too, but
the TFT has so many advantages over the CRT, that I can live with
the slightly smaller gamut of the TFT compared to the CRT.

What people often don't realize is the fact that there're many
different TFT panels out there with very different specifications.
In the cheapest TFT's, you'll often find MVA, TN and TN+ panels.
They seem to have nice specs. _on the paper_, but compared to
TFT's with IPS and S-IPS panels, they're often worth nothing
when it comes to colours. You won't find IPS and S-IPS panels
in the cheap TFT's. Only the more expensive ones (like the Apple
Studio Display for instance) has IPS or S-IPS panels.

On the following link you'll see the tonal response and the
correction that OptiCAL makes to my TFT. (I calibrate it to a
gamma of 2.2 and native as the whitepoint, which is around 6050K
according to OptiCAL although the onscreen display of the monitor
says 6500K, which is the default setting).

<http://home18.inet.tele.dk/madsen/monitor/calibration>
(It's a Viewsonic VP201a TFT with an IPS panel).

--
Regards
Madsen.

Greg

2004-01-25, 2:28 am

"Thomas Madsen" <nospam@madsen.tdcadsl.dk> wrote in message
news:Xns947B211518F00.thomas@madsen.tdcadsl.dk...

quote:

> Greg wrote:
>
>
> I don't see an "S" response on my TFT but I'm definitely not
> seeing a linear tone response either. No monitor has a linear
> tone response, as far as I know.

I see an incy wincy bit of an S response - there's a kink right up near the
top of the scale. :)
Seriously though, yes, it does look very well behaved. (CRT-like)

Regarding "linear", I just meant perceptually linear. I realise that a CRT
has a non-linear
response in terms of absolute light level vs voltage.

Greg.

Thomas Madsen

2004-01-25, 9:28 am

Greg wrote:

quote:

> Regarding "linear", I just meant perceptually linear.

Ahh, okay. :)

--
Regards
Madsen.

KBob

2004-01-25, 4:28 pm

On Sun, 25 Jan 2004 01:42:25 -0000, Graeme Cogger
<gcogger@bigSPAMfoot.com> wrote:

quote:

>In article <40130c3b$0$26115$afc38c87@news.optusnet.com.au>,
>nospam@nospam.com says...
>
>Adobe Gamma does not generally work well with TFT monitors,
>although it wasn't too bad on my Sharp LL-T1620 so it's worth a
>try. There are various 'cheap' calibration systems available
>that manage TFT's pretty well, but they cost around $200 or
>more.

Adobe Gamma worked fairly well on my ViewSonic VX2000 (21" LCD), but
Optical/SpyderPro worked better IMHO.

Loren Amelang

2004-01-25, 4:28 pm

On Sun, 25 Jan 2004 03:15:07 +0100, Thomas Madsen
<nospam@madsen.tdcadsl.dk> wrote:

quote:

> What people often don't realize is the fact that there're many
> different TFT panels out there with very different specifications.
> In the cheapest TFT's, you'll often find MVA, TN and TN+ panels.
> They seem to have nice specs. _on the paper_, but compared to TFT's with
> IPS and S-IPS panels, they're often worth nothing when it comes to
> colours. You won't find IPS and S-IPS panels in the cheap TFT's. Only the
> more expensive ones (like the Apple Studio Display for instance) has IPS
> or S-IPS panels.

For those like me who aren't clear what these acronyms mean, check
<http://www4.tomshardware.com/displa...114/lcd-04.html> for a short
intro. (One of the very few in English - why is it that there is lots of
discussion of TFT types in German, Polish, Chinese and Japanese, but almost
none in English?)

But they don't mention S-IPS - do you have a link or clue what this adds?

When you mention the "Apple Studio Display" as being IPS or S-IPS, I don't
suppose that includes my original 15" Bondi Blue model with the Apple
connector (as opposed to the PC-VGA connector on later colors)? Or does it?
Can one tell by looking?

Loren

Thomas Madsen

2004-01-25, 10:28 pm

Loren Amelang wrote:

quote:

> (One of the very few in English - why is it that there is lots of
> discussion of TFT types in German, Polish, Chinese and Japanese,
> but almost none in English?)

I don't understand it either, but you're right. I've noticed the
same thing.
<http://www.meko.co.uk/ipswitch.shtml> tells a little about IPS
and MVA panels but that's all I've ever found on an English site
(besides tomshardware.com). Many sites doesn't seem to know that
there're different TFT types out there.

quote:

> But they don't mention S-IPS - do you have a link or clue what
> this adds?

As far as I know, S-IPS is newer than IPS and has improved colour
purity, higher viewing angels and quicker response times over IPS
panels. I don't know if you understand German, but you can find
it mentioned here: <http://www.prad.de/new/lexikon/s-ips.html>.

quote:

> When you mention the "Apple Studio Display" as being IPS or S-IPS,
> I don't suppose that includes my original 15" Bondi Blue model
> with the Apple connector (as opposed to the PC-VGA connector on
> later colors)? Or does it? Can one tell by looking?

When I mentioned the Apple Studio Display, I meant these:
<http://www.apple.com/displays/>. They only come in 17", 20" and
23", and I'm not sure whether they have IPS or S-IPS panels, but
I've heard from different sources that it's either IPS or S-IPS.
Their specifications indicates that it's probably IPS with viewing
angles of 170°(horizontal and vertical), brightness of 200 cd/m²
and contrast ratios around 350:1. That's very typical specs. for
IPS panels.
My sister has the 23" Apple Studio Display, an as far as we can
see, it's very similar to my Viewsonic VP201s(*) when we compare
them to each other, so I'm pretty sure that the Apple Studio
Displays has either IPS or S-IPS panels.

(*) I wrote VP201a in <news:Xns947B211518F00.thomas@madsen.tdcadsl.dk>
but that was a typo. The name is VP201s.

--
Regards
Madsen.