Dan Margulis Applied Color Theory
Sending LAB Files to Inkjet Printers
LAB to Inkjet Printers
Posted by: Dan Margulis
Wed Jul 25, 2007 4:03 am (PST)
One Photoshop World instructor and one of my class
students have told me that they routinely send LAB, rather than RGB files,
to their inkjet printers. I have always been wary of doing this because I
thought it was such an uncommon practice that there would be a danger of
running into some bug that isn't documented because of lack of usage.
Is anybody else aware of people who are sending LAB to
inkjet printers, and is there any record of problems in doing so?
Dan Margulis
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Re: LAB to Inkjet Printers
Posted by: Randall Hoffner
Wed Jul 25, 2007 4:40 pm (PST)
I do it with some regularity, and have had no problems
that I am aware of.
Randy Hoffner
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Re: LAB to Inkjet Printers
Posted by: "Jim Bean"
Wed Jul 25, 2007 5:55 pm (PST)
I never do it, except by mistake... but ran a small
wedding, every other image lab, then all duplicate order printed as lab...
could not tell the difference between the rgb/lab prints or experience any
problem... epson76-9600
best, jim bean
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Re: LAB to Inkjet Printers
Posted by: Ric Cohn
Wed Jul 25, 2007 5:56 pm (PST)
I've generally avoided it too, but I have printed LAB
files by mistake and I have never seen any difference. One color expert I
mentioned this to said there shouldn't be a problem (based on his
understanding of how the CMS works}. I'm still wary, but maybe I shouldn't
be?
Ric Cohn
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Re: LAB to Inkjet Printers
Posted by: "John William Lund"
Wed Jul 25, 2007 7:57 pm (PST)
I have not seen any issues the few times I have sent
LAB files thru a non-Postscript driver.
Howerver, I have seen quirky behavior from at least one
RIP - as I recall, the ColorBurst RIP (version 4, don't know if this
continues in v5) performed an Absolute Colorimetric conversion to the paper
profile, despite user settings to the contrary. This resulted in a tint of
"paper white" being printed on areas that should have been clean
whites.
John W Lund
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Re: LAB to Inkjet Printers
Posted by: "Rich Wagner"
Wed Jul 25, 2007 7:58 pm (PST)
Bill Atkinson actually delivers his test images on his
website in the LAB space. (http:
//homepage.mac.com/billatkinson/FileSharing2.html) If Bill does this (and
he has for years) and has not had a problem, I would be surprised if
someone else discovered a problem doing the same thing. I've personally
never had a problem printing Bill's Lab test images, nor have I heard from
anyone else that they have. These images are certainly in widespread use.
--Rich Wagner
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Re: LAB to Inkjet Printers
Posted by: "Rich Wagner"
Wed Jul 25, 2007 9:43 pm (PST)
Just to make sure this is clear, technically speaking,
data in the Lab color space is not "sent to an inkjet printer."
Somewhere before the data stream is sent to the printer (e.g., in Photoshop
or the printer driver), the Lab data is converted to the (hopefully)
appropriate printer profile space (and then to the 6+ channels), or the
image will look like crap. For this reason, Bill refers to the images as
"printer profile test images."
I also routinely send Bill's Lab images through the
ImagePrint RIP (v6) without problem (and with good results) when testing
profiles. I don't use the ColorBurst RIP, so I can't comment on the problem
John Lund referred to.
--Rich Wagner
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Re: LAB to Inkjet Printers
Posted by: "mcenigma"
Thu Jul 26, 2007 9:14 am (PST)
Hello,
I have made many prints using the file in LAB, one time
I mention that to a Photoshop guru, and I got and ear full.. of how I mess
with the information, how I got the file out of the printer gamma.
Even when I show my prints, and he like them... his
best comment was... so far is going good, but is going to be a bad one
soon.
thanks
Juan G. Aguilera Fernandez
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Re: LAB to Inkjet Printers
Posted by:Henry Davis
Thu Jul 26, 2007 10:08 am (PST)
The concern of printing from Lab is more than just if
it can be done. There are color values in Lab that don't display
accurately. What you see on the monitor may not be accurate with regard to
the output. The "so far, so good" comment you got might have been
a suggestion that you have not yet been surprised by any of these colors.
Henry Davis
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Re: LAB to Inkjet Printers
Posted by: "Bill Morse"
Thu Jul 26, 2007 2:26 pm (PST)
The critical thing in printing from LAB is really the
same as from any other color space. You have to know how the colors will
convert, and you either have to do the conversion yourself, or you have to
have confidence that your printer will convert the file using the settings
that you have previously determined will give the best results.
My typical practice is to convert in PS; I have several
actions that convert using different parameters (different output profiles,
different conversion settings). However, I almost always will make small
changes to the CMYK file, especially in the very darkest areas. I have a
cmyk curves setting that I normally start with, then tweak. The action then
sends the CMYK file to the RIP.
--
Regards,
Bill Morse
Wm. Morse Editions
(617) 429-3298