Grant,

in my humble opinion you've got strange advice.

Printer calibration (toner or inkjet) has absolutely nothing to

do with working spaces like sRGB or offset processes like ISO

Coated.

One prints a so called target which is entirely defined by some-

what round combinations of CMYK values (percentages 0, 10, 20

... 100 each  channel).

After drying the print, the CIELab values are measured by a

spectrophotometer, for instance EyeOne Pro, followed by gene-

rating one or more profiles, for instance by GretagMacbeth

ProfileMaker .

The ICC profile consists essentially of multidimensional tables

L a b --> C M Y K  and  C M Y K --> L a b.

That's all, with one exception: some printers require in advance

to the mentioned process a so called linearization, which can

improve the accuracy, but without enlarging the gamut.

Everything for one ink set, one paper or medium, one type of#

rasterization (different target prints) and many other parameters,

for instance the kind of Gray Component Replacement (GCR) 

(different profiles based on the same target print).

Once you've got your ICC profile, you can use documents with

any sources:

Images in sRGB, aRGB (Adobe RGB), images and vector graphics

in any CMYK space like ISOCoated v2 eci or SWOP.

Source profiles are defined in a Raster Image Processor (RIP)

or in Photoshop. Destination profile is your measured ICC profile

(evtl. plus linearization).   

Therefore feel free to use any source profile. Personally I'm using

for Inkjet: aRGB for Images and device CMYK for Text and vector

graphic.

for Offset: CMYK for everything. The ICC profile as recommended

by  the print house. This is assigned to the standard process, even

if the paper should be different.

The conversion from RGB to CMYK should be supervised by soft-

proofing in Photoshop (estimated appearance in CMYK), neces-

sary corrections in RGB.

For gray images, to be printed by K-only,  one has to observe the

whole process carefully (preferably delivered as CMYK with void

plates CMY).

InDesign handles documents with different colorspaces correctly,

but gray images with gamma other than 2.2 are not shown as

they should be - one reason for not using gray, but CMYK-->000K.

Illustrator cannot carry ingredients with different color spaces simul-

taneously - very bad for general processes.

Best regards --Gernot Hoffmann

P.S.: everything valid for professional toner printers or inkjets,

namely for PostScript printers - not for 'office printers'.

Minor corrections edited by the author