Re: [Gimp-print-devel] Inquiry Regarding Custom Inkset Control and ESC/P2 vs. ESC/P-R Clarification

[Solomon P. <pi...@sh...>]

On Tue, Jun 10, 2025 at 02:53:28PM -0700, Kevin Hu via Gimp-print-devel wrote:
> Information about ESC/P-R appears scarce, especially regarding how it 
> differs from ESC/P2. Given that Gutenprint lists support for some 
> ESC/P-R printers (like the XP-15000), is it appropriate to assume that 
> ESC/P-R largely overlaps with ESC/P2 but includes additional 
> high-level commands, or is it fundamentally distinct?

It is my understanding that ESC/P-R presents only higher-level commands 
whereas ESC/P2 operates at a fairly low level.  /P2 gives you full 
control of the individual ink dots but requires you to handle all of the 
color->ink mapping, dot size/patterns, density, dithering, etc to yield 
usable output.  /P-R takes in a RGB (and presumably other colorspaces) 
raster and the desired output parameters (media, resolution, quality, 
etc etc) and the printer handles mapping that to the individual ink 
droplets.

Some printers support both command languages, but others only support 
one. (typically /P-R for modern consumer-grade models, /P2 for 
commercial/industrial gear)

> Despite thorough review of the documentation on rasterization and 
> color handling, I remain slightly concerned whether printers perform 
> any additional internal processing of the rasterized data we 
> send—particularly, could commanding specific CMY channels 
> inadvertently activate the K channel in the printer's internal 
> processing?

I can't speak authoratitively on all implementations of ESC/P2, but it 
is my understanding that they do not perform any internal processing of 
the data they are supplied.  Gutenprint itself will only utilize a K 
channel if so requested.

(ESC/P-R by defninition does all sorts of processing to map the input 
raster to ink dots. I have no idea how much customization is allowed)

> Does this mean that for printers with min_nozzles equal to
> the total nozzle count, all nozzles must actively be used at some point
> during each print cycle? Does this mean that for full control of individual
> channels, we need to select printers that do not require all of the nozzles
> used?

My understanding is that this means the printer may require that data 
for a given ink channel may always need to be present.  However, that data 
can be completely "blank", ie no ink gets deposited.

 - Solomon
-- 
Solomon Peachy			      pizza at shaftnet dot org (email&xmpp)
                                      @pizza:shaftnet dot org   (matrix)
Dowling Park, FL                      speachy (libera.chat)