Archived posting to the Leica Users Group, 2006/02/07

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Subject: Digital FAQ was: Re: [Leica] Tina and Digital (was, Enlarger
From: jonathan at openhealth.org (Jonathan Borden)
Date: Tue Feb 7 15:20:59 2006
References: <NEBBJDFBIKOBILIKPPBNOENIDLAB.red735i@earthlink.net> <3.0.2.32.20060206182132.02b034d8@pop.infionline.net> <NEBBJDFBIKOBILIKPPBNOENIDLAB.red735i@earthlink.net> <3.0.2.32.20060206195407.02b0790c@pop.infionline.net>

Marc James Small wrote:

> At 06:43 PM 2/6/06 -0500, Tina Manley wrote:
>
>> You don't really need a RIP.  You can print directly with the
>> profiles provided by Epson and get pretty good results.  If you want
>> wonderful results, you will go with a free profile available on the
>> internet.  There are profiles for every paper and ink
>> combination.  Just Google them. When you think of how many
>> combinations that is, you can understand why they are not all
>> provided with the printer.
>
> You still have not defined what an "RIP" is -- Raw Induced Psychosis?
> Really Insipid Pseudo?  Rascals In Psoriasis?  What does it MEAN?
>
> And the rest of your scribe is even more frightening.  What is a  
> "profile"?
>  and what, then, is a "free profile"?
>
> Give me chemistry.  That I undersand.

Hah. Digital imaging probably isn't more complicated than  
chemistry ... it just has its own domain of knowledge.

Regarding a RIP --- back in the old days screens and printers were  
divided into two types: vector devices which draw lines (e.g. an  
oscilloscope) and raster devices for which pictures are made of a  
stack of generally horizontal lines of varying intensity ... the  
television is the archetype. see: http://en.wikipedia.org/wiki/ 
Raster_graphics and http://cjs.cadmus.com/da/glossary.asp

- a "RIP" is a "Raster Image Processor" which is essentially just a  
fancy driver for a printer, or a fancy program which controls a  
printer or group of printers. You can forget about RIPs for the  
moment -- you'll know when you might need one, but that is only after  
you learn a bit more than the basics of printing.

A "profile" on the other hand is an important concept to understand.  
Basically different films, monitors, scanners, printers, inks and  
papers have slight differences in how they respond to and render  
colors. A "profile" is a method to quantitate this. A profile is  
directly analogous to the "Zone system" for digital imaging. Let me  
explain with an example. Suppose you have a piece of artwork or  
object that you want to copy with as faithful colors as possible, for  
example a red white and blue flag.

Traditionally you might take a photograph of this develop it, and  
print it. You might then compare the colors to the original and then  
add and or substract color filters until the print has the same  
colors as the flag. This process of developing corrective filter  
values is a "profile".

For example different films will render colors slightly differently  
-- a profile measures this and supplies adjustment curves to  
neutralize the differences between films. Likewise each scanner might  
respond slightly differently to different colors, and each monitor  
might display colors slightly differently and each printer and each  
type of ink and ultimately each paper.

Profiles are typically made using color targets just as with  
traditional color darkrooms, and densitometers that precisely measure  
colors so that linearization curves can be developed for each brand  
of film, (or digital sensor on a camera) each individual monitor,  
scanner, printer and each brand of paper such that an image is  
printed as close to the way it looks on the screen as possible.

Some people make individual profiles for their own printers and each  
brand of paper they print on. Creating such profiles requires an  
expensive densitometer (at least creating a high quality profile  
does). Some profiles are created with sampling a few colors, and  
others by sampling hundreds of colors. "Free profiles" are typically  
created by the manufacturer of a paper for use with a particular  
brand of printer. "Pro" printers such as the Epson 4800/7800/9800 are  
linearized by hand at the factory and as such have a profile built  
into them, but there is much more individual variation with consumer  
grade printers. To correct for the printer to printer variations many  
people have custom profiles made by printing out a target (blocks of  
color) and having someone with a densitometer (and a piece of  
software) create a profile which is a file with a file type of "ICC"  
or "ICM".

IMHO the most important feature of the full Photoshop program is that  
it is entirely profile enabled.

Now if you find the learning curve too steep, why don't you simply  
use a Mac and a digital camera. When you plug the camera into the Mac  
(via a cable) the iPhoto program will launch itself and you can print  
out the photo. Or get a printer that the camera plugs into directly  
and you don't even need a computer. If you want film, try shooting in  
C41 (slides and b/w also work), get a scanner, get the Vuescan  
program. Scan the neg and then load it into iPhoto. As long as you  
are happy with the colors don't worry and just be happy. If your  
prints don't look the same as your computer screen then profile your  
monitor (System Preferences -> Monitor -> Color -> Calibrate ...). If  
you still aren't happy with the colors then try adjusting them with  
the sliders. If you still aren't happy then you need Photoshop where  
you can deal with profiles for your printer/paper and you can apply  
all sorts of color adjustment curves etc ...).

If you aren't happy with this advice, then as we say: "There are many  
ways to skin a cat" but this is one way to skin a cat from someone  
whose skinned some cats.

Jonathan

In reply to: Message from red735i at earthlink.net (Frank Filippone) ([Leica] Tina and Digital (was, Enlarger)
Message from msmall at infionline.net (Marc James Small) ([Leica] Tina and Digital (was, Enlarger)
Message from msmall at infionline.net (Marc James Small) ([Leica] Tina and Digital (was, Enlarger)