Color Value

[Dirtroadie]

Does anyone know what RGB or CYMK color value is equivalent to the
color of "photo cyan" or "photo magenta" as used in 6 (or more) color
printers that use those inks? And would Canon's "photo magenta" be
expected to be the same as Epson's or HP's?

Or in another way of looking at it, if I created a block of solid color
in a Photoshop image, what RGB or CYMK value would I assign so that it
would print out using a single "photo" inks and no other inks?

I would speculate that "photo magenta" is something like 50% magenta
(C0, Y0, M50, K0) but I am looking for actual technical specs.

DR

 

[Gary Tait]

Does anyone know what RGB or CYMK color value is equivalent to the
color of "photo cyan" or "photo magenta" as used in 6 (or more) color
printers that use those inks? And would Canon's "photo magenta" be
expected to be the same as Epson's or HP's?

Or in another way of looking at it, if I created a block of solid color
in a Photoshop image, what RGB or CYMK value would I assign so that it
would print out using a single "photo" inks and no other inks?

I would speculate that "photo magenta" is something like 50% magenta
(C0, Y0, M50, K0) but I am looking for actual technical specs.

DR

Its just slightly diluted of the other two.
It could be 50% though.

 

[Bob Headrick]

Does anyone know what RGB or CYMK color value is equivalent to the
color of "photo cyan" or "photo magenta" as used in 6 (or more) color
printers that use those inks? And would Canon's "photo magenta" be
expected to be the same as Epson's or HP's?

Or in another way of looking at it, if I created a block of solid color
in a Photoshop image, what RGB or CYMK value would I assign so that it
would print out using a single "photo" inks and no other inks?

I think you would have to experiment. At least for HP printers it would depend
on which printer model and what driver and paper type is selected. The photo
inks do not directly map to the CMYK values in Photoshop.

Regards,
Bob Headrick, MS MVP Printing/Imaging

 

[Dirtroadie]

I think you would have to experiment. At least for HP printers it would depend
on which printer model and what driver and paper type is selected. The photo
inks do not directly map to the CMYK values in Photoshop.

Thanks, while that doesn't answer the question directly it is useful
information.
I suspect that the same must be true for all printers. And of course
any tweaking of the actual color settings for a given printout will
change the nature of the applied inks too.

As to "experimenting," I am hard pressed to determine a way of
assessing which inks are applied to the paper under any given set of
circumstances. My goal was really just the opposite - to actually
control which inks are used. That may be well beyond the scope of
anything which is feasible without knowing how to control a printer
directly such as is done in a typical "nozzle check" printout
controlled by the driver for a given printer.

DR

 

[Bob Headrick]

Thanks, while that doesn't answer the question directly it is useful
information.
I suspect that the same must be true for all printers. And of course
any tweaking of the actual color settings for a given printout will
change the nature of the applied inks too.

As to "experimenting," I am hard pressed to determine a way of
assessing which inks are applied to the paper under any given set of
circumstances. My goal was really just the opposite - to actually
control which inks are used. That may be well beyond the scope of
anything which is feasible without knowing how to control a printer
directly such as is done in a typical "nozzle check" printout
controlled by the driver for a given printer.

This is certainly more difficult than it sounds like it should be, but I do not
know of an easier way. The control codes to directly control the nozzles are
not typically publicly documented, at least for the HP printers I am familiar
with.

As for the method of trial and error, for cartridges with integrated printheads
and ink supplies (such as the HP #57/58) you could do the following rather
laborious procedure: take two pairs of cartridges. In one set deprime the
cyan and light cyan (or the light magenta and magenta). Now print color ramps
from Photoshop, using the good color cartridge and the deprimed photo
cartridge, then with the good photo cartridge and the deprimed color cartridge.
Using a microscope find which color shades correspond to the desired pure
color. Be aware that some printers have additional capabilities to self
calibrate for differences between drop size of different cartridges and other
factors. This would further complicate things....

There is probably a more straightforward way to do what you want. What is your
actual application?

Regards,
Bob Headrick

 

[Arthur Entlich]

I would expect each manufacturer to use different values.

In part, the light value M and C colors are about how much ink can be
used up and sold. Each company will have differing mixes and their own
drivers to make the mix work. They could easily even differ from one
printer model to another within the same brand.

Art

 

[Dirtroadie]

There is probably a more straightforward way to do what you want. What is your
actual application?

Well, a couple of things.
1. Printing out a "pure" swatch of ink for the purpose of ink color
comparison.
2. Printing out a single color to purge a nozzle without using any
other colors.
DR

 

[Bob Headrick]

I would expect each manufacturer to use different values.

In part, the light value M and C colors are about how much ink can be used up
and sold.

I have been involved in development for a number of cartridge programs and have
never heard that as a consideration. The values for the light dye loads are
typically a careful tradeoff of print quality and print speeds. With a light
dye load that is too dark prints will have more visible grain. With a dye load
that is too light too much ink will be put on the media and dry time and other
factors will be affected.

Regards,
Bob Headrick, MS MVP Printing/Imaging

 

[Bob Headrick]

Well, a couple of things.
1. Printing out a "pure" swatch of ink for the purpose of ink color
comparison.
2. Printing out a single color to purge a nozzle without using any
other colors.

To do the first you can use the nozzle diagnostic or self test pages - there
will typically be one that will print color blocks for each chamber.

For the second I doubt that you would get 100% satisfaction, but you should be
able to get in the ballpark with some trial and error. Letting the printer
handle the servicing automatically usually gives better results.

Regards,
Bob Headrick, MS MVP Printing/Imaging

 

[Dirtroadie]

To do the first you can use the nozzle diagnostic or self test pages - there
will typically be one that will print color blocks for each chamber.

True, but without any controll of the size, placement or intensity of
the blocks.

For the second I doubt that you would get 100% satisfaction, but you should be
able to get in the ballpark with some trial and error. Letting the printer
handle the servicing automatically usually gives better results.

Yes that generally works, but I have found it frustrating to have one
color not working well and then use up a bunch of ink from ALL colors
trying to clean up the output of the bad color. And, yes, a rough
estimate of color would work but while contemplating the issue my anal
side thought that some degree of precision control might be desirable.

In any case, this is more of an academic excerise than an attempt to
solve a significant problem.

DR

 

[Arthur Entlich]

Let me put it another way then.

Four color ink sets with a small enough dot come very close to rivaling
the image quality of a six color printer, especially at viewing
distance. Admittedly, use of a very small dot (i-1.5 picolitre)
requires some careful head design, a faster head and electronics to
produce more dots, and ink that can create that small a dot.

Canon has done this with their i5000 series as I recall. This printer,
as a result, uses a heck of a lot less ink, because the "lighter colors"
are made from the white of the paper showing through rather than the use
of weak dye loaded inks.

Not only that, but a full dye load ink small dot have better archival
abilities than a dilute ink will.

Lastly, these dilute inks have drivers to use them up usually at twice
the speed of the full dye ink. Considering that the dye itself is
usually the most costly component of the ink, the load dye load or photo
inks are the most profitable business for inkjet companies. The ink
costs less to make, the ink is used up at twice the speed of high dye
load inks, and they fade more rapidly.

I tend to see this approach to inkjet design as a costly answer to the
consumer, when a smaller ink dot would recover much of the "benefit"
these low dye inks have, without the considerable extra cost to
the end user.


Art

 

[Dirtroadie]

I would speculate that "photo magenta" is something like 50% magenta
(C0, Y0, M50, K0) but I am looking for actual technical specs.

Maybe not. I now see that Canon refers to some photo inks as "1/6
density."
DR