[Digikam-users] Re: SRBG, Adobe RGB, What to use ?

[Martin (KDE)]

Am Montag, 27. Juni 2011 schrieb Sebastian Schubert:
> On Sonntag 26 Juni 2011 19:31:14 Martin (KDE) wrote:
> > A big disadvantage of AdobeRGB (and other colour spaces) with
> > jpeg files is the limited range of available bits. For standard
> > jpeg you have 8 bits per colour channel (RGB). The wider your
> > gamut the bigger the steps between two values.
> > 
> > If you use a colour space with double range of blue compared to
> > sRGB (as an example) you still have only 256 different types of
> > blue. If your photo uses the complete range your are fine. If
> > your photo uses only the range defined in sRGB you have only 128
> > different steps of blue So you loose quality. (This assumes the
> > colour spaces are linear which they are not but it is easier to
> > compare).
> > 
> > AdobeRGB is only a little bit bigger than sRGB so the advantage
> > is only limited.
> 
> How severe is the problem of only 8bit in jpg using AdobeRGB? My
> monitor shows AdobeRGB almost completely, so I wanted to use
> AdobeRGB jpgs (so far only browsing and creating RAW development
> settings).

Most likely you will not notice it. the difference is visible in 
saturated colour only. If you are able to read german please take a 
look at http://foto.beitinger.de/adobe_rgb/index.html This article 
shows advantages and disadvantages of sRGB-AdobeRGB very well.

And: the AdobeRGB does not help that much if your printing-lab can not 
handle the AdobeRGB range.

To my point of view the best is to use the raw data as long as 
possible. If you need to postprocess your photos, use a 16bit ProPhoto 
colour space in i.e. png format. At the end of your process, convert 
the photo to the medium and colour space your enduser (printing-lab, 
webpage ...) can handle best. For web pages this will most likely be 
sRGB and jpeg as well as for printing labs (except for very large 
prints). This is a similar way Adobes Lightroom is working.

I heard rumours that some users do not use integer base photo formats 
but floating point one instead. At a first glance this sounds 
ridiculous. But you will get an infinite amount of colours. The next 
round will come: integer vs. float.

Martin

> 
> Cheers
> Sebastian