ECIRGB versus LstarRGB
by Markus Hitzler, Color Solutions
Hello,
Am 01.06.2005 0:28 Uhr schrieb "eci-en-request(a)lists.transmedia.de" unter
<eci-en-request(a)lists.transmedia.de>:
From: Chris Murphy <lists(a)colorremedies.com>
Subject: Re: [ECI-EN] ECIRGB versus LstarRGB 2
...
>
> I think the choice between ECI-RGB, Adobe RGB (1998), and Lstar-RGB is
> almost like splitting hairs or trying to find out how many angels can
> dance on the head of a pin. Sometimes a project calls for this level of
> scrutiny, most do not.
Chris, if we talk about the gamut of this color spaces I'm absolutely with
you.
But the main difference is not the gamut, it's the distribution of the RGB's
inside the Gamut or in other words: the encoding efficiency.
One little example:
Let's look to the dark tones at the grey axis of Adobe-RGB and LStar-RGB.
Because both profiles are matrix systems and grey is build by the same
values of red, green and blue the examination of the grey axis shows the
situation of the 3D-distribution too.
With Adobe-RGB you need 20 points (0-19) to describe the luminance range of
L*=0 to L*=3. In other words: you use nearly 10% of your coordinates to
encode only 3% of your color space. Moreover: very often you don't have
image information at this luminance range but the noise of your imaging
system.
Therefore you loose coordinates for the exact encoding of the other areas
with image information.
LStar-RGB on the other hand has a distribution, which is directly related to
the human eye: you use 3% of your coordinates to describe this darkest 3% of
your color space. Therefore the LStar-RGB color space is able to save up to
5% more visual information compared to Adobe-RGB.
The LStar-method produces the highest possible encoding efficiency with
respect to the visual appearance inside the gamut of the color space.
That's the point. Therefore LStar color spaces are at the moment the best
solution to save image information at a given color gamut and bit depth.
Unfortunately the documentation on www.LStar-RGB.com is only available in
German at the moment. We're working on the translation. But graphics are
"international": on the last page you can find a diagram (RGB vs. L*) which
shows the trouble with gamma curves very good.
The actual "LStar-RGB" color space combines the well-tried gamut of ECI-RGB
with the superior even distribution of CIELAB. If you need color spaces with
LStar-distribution but an other color gamut, please contact us.
Kind regards,
Markus Hitzler
___________________________________________
Color Solutions Köln
Markus Hitzler
August-von-Willich-Str. 155
50827 Köln
Telefon: +49 (0)221 99 175 80
Fax: +49 (0)221 99 175 81
Mobil: +49 (0)171 8390333
Email: markus.hitzler(a)color-solutions.de
Web: http://www.basICColor.de
___________________________________________
basICColor - the basICCs of colormanagement
___________________________________________
18 years, 11 months
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RE: [ECI-EN] ECIRGB versus LstarRGB
by Bestmann, Guenter RD-PN32
Hello!
Images with 16 bit resolution in general do not need any compression or gamma curves. They can be stored as transmission or reflection data (linear data). If you are converting to 8 bit data formats you need some compression of the dynamic range (Lstar, gamma, modified gamma with linear sloop in the shadow area). Different color spaces use different parts of the coding range. With 16 bit resolution you can use any color space that is large enough not to clip any colors. Using 8 bit resolution you should use a color space that is large enough that all possible codings were not clipped and small enough not to waste space. Wide gamut color spaces in 8 bit coding tend to create artifacts like bending. Therefore it is best to choose a smaller color space in this case (AdobeRGB, ECIRGB).
Guenter Bestmann
________________________________
From: eci-en-admin(a)lists.transmedia.de [mailto:eci-en-admin@lists.transmedia.de] On Behalf Of Jón A Sandholt
Sent: Wednesday, June 01, 2005 2:23 PM
To: ECI
Subject: [ECI-EN] ECIRGB versus LstarRGB
This is a very interesting discussion, wich I have been following with great interest.
I have a question that relates to this topic.
How does bit depth ( 8 bit vs 16 bit etc.) relate to all this.We are told that 8 bit color can give us about 16,7 million colors and 16 bit something much more (I don't wont even try to do the calculations).I know this is only in theory but lets say you have a 8 bit image in ProPhoto RGB and one thats 16 bit in the same colorspace, is there a difference between them as to how much part of the space they use?
What I'm trying to say is does a high bit image make a better use of a large colorspace than the 8 bit one?
Am I missing some point here or misunderstanding something?
Thanks again for very intersting discussion.
Best regards.
Jón A Sandholt
18 years, 11 months
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RE: [ECI-EN] ECIRGB versus LstarRGB 2
by kristoff.decroix＠roularta.be
Hi,
You're talking about ECIrgb and LStarRGB.
What about Adobe RGB 1998?
Is Adobe RGB 1998 not sufficiant anymore as RGB-colorspace?
Should we change to ECIrgb or to LStarRGB?
And why should we change?
Kristoff Decroix
Roularta Publishing
Repro Quadri / Color Management
kristoff.decroix(a)roularta.be
tel 00-32-(0)51-26 69 59
-----Oorspronkelijk bericht-----
Van: eci-en-admin(a)lists.transmedia.de [mailto:eci-en-admin@lists.transmedia.de] Namens Karsten Krüger
Verzonden: woensdag 1 juni 2005 9:38
Aan: eci-en(a)lists.transmedia.de
Onderwerp: Re: [ECI-EN] ECIRGB versus LstarRGB 2
Am 01.06.2005 um 00:27 schrieb Chris Murphy:
> Personally, I would edit in the largest space you can find and just
> stick with it. I regularly use ProPhoto RGB. It's honking huge. On the
> surface this doesn't sound like it would be an advantage just because
> the gamut is so much larger than anything you'd print to, what's the
> point? Well, because the gamut is so large, there it also has a larger
> shadow end gamut as well, and there are quite a few colors that exist
> down there that *are* printable, in particular on ink-jet printers,
> but do not exist in smaller RGB spaces.
>
Chris,
I agree with you that a large colorspace has benefits. But you have to
be very conscious on what you are doing. Using ProPhoto RGB leaves you
with just one choice of color rendering: colorimetric. If you are using
photographic rendering your resulting image will be very small compared
to any other RGB colorspace. But colorimetric rendering is often not
sufficient, because there are likely out of gamut colors in digital
photography (i.e. in blue tones). For my experience the most
predictable and accurate reproduction of an image will happen when you
are as close as possible to the final output colorspace, which for
ISOcoated / european CMYK is LStar-RGB / ECIrgb and for internet
related work sRGB.
An other drawback of ProPhoto RGB is that you will hardly find a
monitor that is able to reproduce the whole colorspace. So you end up
editing data you are not able to see on your monitor and not able to
print out later...
Thanks for your comments anyway,
Karsten
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18 years, 11 months
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