Re: Why don't drivers use a CMYK profile?
Re: Why don't drivers use a CMYK profile?
- Subject: Re: Why don't drivers use a CMYK profile?
- From: Dave Camp <email@hidden>
- Date: Wed, 08 Nov 2000 15:00:01 -0800
I guess I wasn't very clear in my information and question. Yes, QuickDraw
hands us the data in RGB, because it's all it knows. But the printer driver
also gets handed the profile that goes with the source image. So, coming
into the print driver is a nice RGB print job complete with a source
profile.
So, why don't drivers use a CMYK profile to convert directly from source RGB
to printer CMYK values, instead of converting from source RGB to printer RGB
to printer CMYK?
Actually, I guess what I'm really wanting to know is: Is there a good reason
not to do that?
Thanks,
Dave
on 11/8/00 1:52 PM, Bruce Fraser at email@hidden wrote:
>
At 2:33 PM -0800 11/8/00, Dave Camp wrote:
>
> I'm putting on my printer driver engineer cap and posing a question that I
>
> have not been able to answer myself...
>
>
>
> Historically, QuickDraw based printer drivers have always used RGB profiles,
>
> and converted to CMYK using algorithms internal to the driver. Thus, the
>
> print job goes from RGB to RGB to CMYK.
>
>
>
> If the images being printed are tagged with source profiles (they can be),
>
> and the printer driver receives the source profiles with the print job (they
>
> do), why don't any of the current inkjet drivers use a CMYK output profile
>
> and let ColorSync do the conversion from RGB to CMYK, thus removing a step
>
> from the process and allowing advanced users more control?
>
>
>
> It seems like an obvious thing, but nobody does it. Is there a good reason?
>
>
Neither Quickdraw nor GDI has any facility for handing off CMYK to a
>
printer driver. They both work exclusively in RGB. Many applications
>
that print through QuickDraw or GDI don't understand CMYK either. And
>
a lot of the printers are CcMmYK rather than CMYK.
>
>
Also, in most drivers the RGB to inkspace conversion and the
>
screening seem to be inextricably mingled...
>
>
Bruce