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

[David Vincent-Jones]

There can be substantial losses between the 16 bit data of a raw file
and an 8 bit version. Compare the histograms of a converted 16 bit file
and the 8 bit version, they will frequently show 'gaps' in the data post
conversion, especially if any data stretching has been done. Those gaps
will invariably show as banding on a finished, decent sized, print.

Add to this the irretrievable data losses incurred in creating the 8 bit
jpg format. One cannot, for instance, reopen a jpg file and tweek the
image later without possible serious information loss. IMHO the whole
jpg scene is one to avoid. jpg is a nice compact format for snapshots
but one that I would advise others to avoid at any cost for serious
photography.

David

On Mon, 2011-06-27 at 15:56 +0200, Sebastian Schubert wrote:
> 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).
> 
> Cheers
> Sebastian
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