Subject: Re: vic gamma control question

From: Toerless Eckert <[email-masked]>
Date: Thu, 18 Sep 1997 15:20:01 +0200 (MET DST)

> It's a shame that Sun doesn't go the extra mile to integrate such
> features into the supplied windowing environment, though again I can
> understand that implementation of user-level control of gamma in X
> might require pretty substantial effort.  Or are there such features
> already, that I'm unaware of?
> 
> On the SS20 with a cg14 buffer, one could place a line of the form
>    
>    /usr/kvm/cg14config -g 2.2 -u 2.2
> 
> in the file /usr/openwin/lib/Xinitrc to control display gamma (set to
> 2.2, the TV industry standard, in the above example).  Although there
> is a ffbconfig command on the Ultra 2, it's not clear from AnswerBook
> how one might use it to do the equivalent of the above gamma change.
> Has anyone else figured this one out?

As far as i can remember, a hardware expert told me, that the RAMdac
on the Creator-graphic does have only two fixed gamma correction tables,
in strict contrast to the one on the SS20 (which is why i still havbe
a SS20 on my desk). Can anyone ACK/NACK this information ? I at least
have not managed to set the creator graphics to anything else than
"linear" and "gamma corrected" visuals, i.e.: two different settings.

(If you think that SS20/SX board is blased-good, i have to admit that
 "stupid-sun" seemingly wanted to save 20cent and only put a 135 Mhz
 RAMdac on it, so that you cannot go to 1600x1280 resolution in 76 Mhz,
 even on a 8 MByte-SX board).

Toerless

---

From: [email-masked] (R. P. Channing ["Rick"] Rodgers)
Date: Thu, 18 Sep 1997 09:13:15 -0400

> From [email-masked] Thu Sep 18 01:57:25 1997
> 
> The gamma correction alternative in Vic is only available on 8-bit displays 
> and your U2 probable have a Creator(/3D) which allows Vic to run in 24-bit 
> mode.

Peter,

Thanks for the explanation -- however, I must say I don't quite
understand why gamma correction would be considered unnecessary just
because one has a 24-bit display (though I can understand that perhaps
implementation of gamma correction is more difficult in this
circumstance).

> By the way, the FFB (the graphics card in Creator-machines) apparently allows 
> gamma correction per window. Have any one here tried that and have a small 
> code-snippet available?
> 
> /P

   

Cheerio, Rick Rodgers