Re: Question about input devices and Icc profiles...
Re: Question about input devices and Icc profiles...
- Subject: Re: Question about input devices and Icc profiles...
- From: email@hidden
- Date: Wed, 14 Jul 2004 09:25:04 -0400
>
>yea... this is the question... the Gamut that any color aplication shows you
of an input device is ONLY tha gamut of the target that you used to do...
no?????
The response range of that device is only measured for points in the target (target values) but is interpolated (and extrapolated) to generate an entire hi-rez color space at a finer grid.
>
>and let me explain please...
>
>All the devices (scaners, digital cameras etc...) capture RGB values =
>
>(normally 8 bit by channel) from 0 to 255 for each color.
>
>And when you make the Icc the Soft is making a relation between the =
>
> "Spectral" colors of the target and RGB answer of the device... this =
>
> means that all the spectral color are "scaneable"...
>
Well, lets say you map a response for the device to a range of colors...
not quite the same, but it effectively maps a "gamut" for the >device...
>
I agree.... but, then, the Gamut of any Input device only depend of the
target that you used..... and then....
The response of the device is only measured at the target values of a given target. If the brightest red in your target is "kodak photo red", with a known Lab value, which maps to 233, 0, 0 on the source capture device, then the profile will not necessarily clip 255, 0, 0 to 233, it will extrapolate it, instead the more desirable case where it interpolates it.
>
What happen when you tray to scan one color that is "out" of the Icc gamut,
becouse is more saturated than the most saturated of the target that you
used to make the Icc?????
With a printer you can map 255, 0, 0 by sending that value to the printer, and defining a "corner" of the gamut limit there. Thats why we say printers have a defined gamut. With a scanner you are working the other direction, and starting with values that will almost certainly *not* hit 255 in any of the channels, so you are defining a response range, but not a hardware gamut limit.
A scanner profile is a profile for that scanner, in conjunction with the type of film or photo print you profiled (meaning what the target was printed on) and will only accurately define those values within the gamut of that paper or film. So colors outside the numbers that the target patches define are not part of the gamut of that media, even if they are within the response range of the scanner.
--
C. David Tobie
Product Technology Manager
ColorVision, Inc.
email@hidden
www.colorvision.com
_______________________________________________
colorsync-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/colorsync-users
Do not post admin requests to the list. They will be ignored.