[Openicc] colord Printing Plans

[Graeme Gill]

peters at skarpetis.com wrote:
> DeviceRGB should be left alone for the cases where the output is RGB. For other output
> colourspaces a default, such as sRGB, should be assigned.

While that may make sense in some cases, it typically leads to user
dissatisfaction in many others.

Typically "dumb" software takes screen numbers (numbers it sends to the
non-color managed display) and dumps them into DeviceRGB values in
PS or PDF or the equivalent in GDI and sends them to the printer.
Typically the printer native RGB space is not the same as the display
RGB space that the application and user expects the colors to be in.

So the correct thing for a color managed RIP to do to meet users (and application
writers) expectations is to interpret the DeviceRGB values in the
users display colorspace and convert to the actual printer devices RGB space.
If the display space is unknown, then sRGB would typically be assumed.

An additional expectation when the RIP is a print server, is that
it will make all the printer devices behave in a similar fashion,
so that a document will look the same, irrespective of the device
it is sent to.

For both these reasons the default should be to define DeviceXXX to be a
particular colorspace. (This is why PS has the "UseCIEColor" flags, and
why PDF has the equivalent default colour spaces option).

Naturally there should be ways of passing DeviceXXX through without
color management for the purposes of calibration, profiling and
application level color management.

Graeme Gill.