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Re: Creating RGB profiles in Photoshop 5?

 CDTobie@aol.com wrote:
>In a message dated 7/28/99 10:28:05 PM, danculb@concentric.net writes:
>>Now whether a Photoshop generated faux RGB profile will work worth a dang
>>is a separate issue. A couple dozen patches in printing inks setup and
>>gain curves is not at all the quality of hundreds of measured patches in
>>profiling software.  But it has worked good enough for a lot of CMYK
>This is a dubious assumption, the reason the few measurements in a Photoshop
>profile make an acceptable press profile, is because they are a pretty good
>description of what the press needs to know. This same data is not a
>necessarily a very good representation of what an RGB process needs to know
>for an accurate result...it might make a fair set of monitor curves, if the
>CMY to RGB conversion was sufficient, but for quality RGB printing this would
>not necessarily be enough.

Actually I wouldn't call it an assumption as much as a possibly
non-parallel comparison.   Howvever, I suspect you are uncategorically
right for six color inkjet printers and for RGB profiles for film printers.
But for four color printers I would categorize that "accurate" as probably
a sliding scale.  Before I got my profile software I could get an
acceptable print on an Epson 3000 by converting to CMYK through a set of
well measured Photoshop 5 printing inks colors.  My only apparent problem
was the lack of the true black curve when printing with StylusRIP.   An RGB
profile created this way (if one can be created this way) should behave
with the same quality as the CMYK printing inks setup printing to StylusRIP
-- though I have some qualms about how it would actually use the data in
the conversion process.

I suspect there are people with more CMYK skill than me who can create even
better CMYK setup using the classic photoshop method who can go beyond my
acceptable level.  So I'm still a bit up in the air on this.  But it brings
up a good experiment -- I'll make a CMYK profile (500+ pacthes) in Color
Synergy and a CMYK profile from a Photoshop classic set-up (8 color
measurements and around 12 to 24 dot gain measurements -depending on how
critical I want to be) and compare them in ColorSynergy's Gamut Viewer.
Then run side by side prints to see if they are  close.

Actually I should have done that long ago rather than just assuming the
500+ patch CMYK profile or the 400+ patch RGB profile will be better and
jumping into it. Somehow when PS 5 came along and messed with my mind on
RGB setup I presumed I could fix everything if I just could make the right
profile.   I'll do a straight comparison this weekend!  I'll assume my
profile making skills  have gotten to about the same level as my printing
inks setup skills (not at the pro-level but at least competent).  If I
can't see the difference then I guess it is bye-bye to profiles (for four
color work at least).  If I can see a significant difference then I will
struggle on with the extra measurements (and maybe an automatic measuring
device) required for profiles.  Need to simplify this somehow and I'm too
much of a printer hacker to buy someones pre-made profiles (though I
reconize the value of that service to non-hackers!).

Dan Culbertson

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