[ptx] Display gamma (was:Vignetting correction in nona)

[Hal V. Engel]

On Tuesday 03 January 2006 07:58 am, douglas wilkins wrote:

snip

> As I see it, there are two areas that need to be addressed. Firstly,
> ensuring that embedded ICC profiles are passed through correctly. Unlike an
> normal image editing application, there is no need for hugin to modify the
> embedded ICC profile or add one if there is no profile.

This is totally correct.  In addition I think that this is more important and 
much simpler then the item below.  If only this were done I personally would 
be a happy camper.

> Secondly, to colour manage the actual images in hugin for accurate display.
> Modifying the display gamma "on the fly" would fall into this area I guess.
> Again, hugin is slightly different and would probably only require an input
> and display profile since we are not doing any colour manipulation, but I
> welcome input on this.

This is also not particularly difficult but also not really critical.

>
> Finally, I was thinking of using lcms for the colour management, mostly
> because I am familiar with it ;-), but also because it is reasonably mature
> and complete. It will add an additional dependancy though.
>

LCMS is light and in wide spread use.  Most linux system will likely have this 
installed by default these days because of other applications that need it.  
  
snip

> Yes, dcraw has come a long way. The only problem that I have with it now is
> that it assumes a sRGB output profile (look at xyz_rgb)and most cameras are
> capable of a far bigger gamut...

You are totally correct about the large gamut of at least the better digital 
cameras.  A typical DSLR will have a gamut that is nearly twice the size of 
sRGB and  sRGB is for the most part a very poor color space to use for 
anything other than the web.  I would recommend either BetaRGB or 
ProPhotoRGB. 

You should try UFRAW which uses the dcraw code but allows you to specify both 
an input and an output profile.  It also can be run as a batch program,  a 
stand alone GUI or a GIMP plug-in.  In batch and stand alone modes it will 
generate 16 bit/color output.

Hal