Digital BW, The Print

Curious if anyone is seeing any difference sending an RGB file vs a 
Greyscale file to the ABW portion of the Epson R2400 driver when 
printing B&W pictures.

I think I am seeing some very subtle "toning" differences, but am 
unsure and am starting to do some tests. Anyone have any thoughts on 
this? Should it make any difference?

Thanks in advance.

Here is some more data. I just sent an RGB file to the ABW driver 
rather than my previously used greyscale and the "tint" of the image is 
still different than my 8x10 work print. So what has changed? Well I 
went up a size in EPSG paper from 8.5x11 to 13x19. So, can different 
batches of paper make a difference? I have also changed some of the ink 
cartridges recently (all K3 inks). My bigger prints look colder and 
greener. So I wil reprint one of the images in the small size to see if 
anything has changed. If so, then ink batches may make a difference. If 
not, then paper batches may make a difference. Thoughts????

Hello Scott,

>Here is some more data. I just sent an RGB file to the ABW driver 
>rather than my previously used greyscale and the "tint" of the image 
>is still different than my 8x10 work print. So what has changed? 
>Well I went up a size in EPSG paper from 8.5x11 to 13x19. So, can 
>different batches of paper make a difference? 

Yes!  Absolutely.  There can be a significant difference in different
production runs.  Right now I have 8x10 and 13x19 boxes of the same
paper (Merlin Smooth) that are different enough in contrast to require
a different adjustment curve for each one.  A paper vendor told me
that on occasion when they order some coating chemicals from a
supplier they are out of it, so they have to go to a different
supplier.  So there can be differences and it is actually common for
there to be some.  I have observed this with quite a few papers over
the past few years. I've seen papers change in color, contrast, and
density, all three in a single different batch (Kayenta and Entrada
most recently).  I've seen differences in dmax among PR batches.


>I have also changed some of the ink cartridges recently (all K3 
>inks). My bigger prints look colder and greener. 

This happened to me as well.  I swapped in a new K3 M cart and
everything was a tiny bit pinker.  Fortunately because of the great
ABW system all it took was moving the H coordinate by a point or two
to correct for it.  I have also experienced slight differences in
Eboni on occasion (in both color tone and dmax).  

Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm

What colour spaces were the respective files tagged as?

> From: Scott Jones <peanutdogs@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Mon, 17 Oct 2005 18:16:21 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] RE: R2400: RGB vs Greyscale to ABW
> 
> Here is some more data. I just sent an RGB file to the ABW driver
> rather than my previously used greyscale and the "tint" of the image is
> still different than my 8x10 work print. So what has changed? Well I
> went up a size in EPSG paper from 8.5x11 to 13x19. So, can different
> batches of paper make a difference? I have also changed some of the ink
> cartridges recently (all K3 inks). My bigger prints look colder and
> greener. So I wil reprint one of the images in the small size to see if
> anything has changed. If so, then ink batches may make a difference. If
> not, then paper batches may make a difference. Thoughts????

"What colour spaces were the respective files tagged as?"
--------------------------------------------------------------
The spaces are either Adobe RGB for an RGB file sent to ABW or a custom 
Dot Gain that I use if a greyscale is sent to ABW.

Sometimes I have sent the file to the printer with "Let printer 
determine colors" and sometimes per I believe Clayton's suggestion, 
with "no color management", but since my RGB files are always in this 
Adobe space, I am not sure that aspect makes any difference.

My latest print just a few minutes ago, came out decidedly with a green 
cast. I seem to have lost all the modest warmth that I would usually 
get with ABW +2/+2 on the toning wheel.

Discouraging.....

Not surprised you are getting different results sending ONE AFTER THE OTHER
the colour file and then greyscale file.  Important: I am not commenting
here about the paper change or the ink change.  These are additional
variables that you need to isolate. When you send the Adobe RGB file - even
if it is a greyscale image in the colour Adobe RGB workspace - you are
sending entirely different pixel values than when you send the file which
has been converted to your custom dot gain space (why are you using this
anyway?).  If the printer gets different pixel values then it will print a
different colour.

Now the practical issue:  I think your problem is likely a mix of that which
I commented on above AND your ink changeover.  Sounds to me like a nozzle
issue or some sort of ink issue (a bum cart).  Do a full nozzle check and
print the MIS purge pattern a few times.  Before doing this remove all the
cartridges, give each of them a good shake and return them to the printer.

Also see below


> From: Scott Jones <peanutdogs@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Mon, 17 Oct 2005 23:00:15 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] Re: R2400: RGB vs Greyscale to ABW
> 
> "What colour spaces were the respective files tagged as?"
> --------------------------------------------------------------
> The spaces are either Adobe RGB for an RGB file sent to ABW or a custom
> Dot Gain that I use if a greyscale is sent to ABW.
> 
> Sometimes I have sent the file to the printer with "Let printer
> determine colors" and sometimes per I believe Clayton's suggestion,
> with "no color management",

For Adv B&W there is no difference between these two.


>but since my RGB files are always in this
> Adobe space, I am not sure that aspect makes any difference.

Correct - when you select no colour management no conversion of pixel data
is done and when you ask the printer to do it the Adv B&W driver ignores the
sent profile.

Hello Scott,

>The spaces are either Adobe RGB for an RGB file sent to ABW or 
>a custom Dot Gain that I use if a greyscale is sent to ABW.
> 
>My latest print just a few minutes ago, came out decidedly with 
>a green cast. I seem to have lost all the modest warmth that I 
>would usually get with ABW +2/+2 on the toning wheel.
>Discouraging.....

Steve is right about RGB/grayscale differences.  I wondered about that
in your original post, but your main questions focused on paper and
ink so I didn't say anything. But FWIW let me relay a bit of past
history about this.

Sometime between 3 and 4 years ago, before Eboni, the 2200 and UC,
when people were still struggling with inks that color shifted and
1280 "clogs from hell" threads were common, there was a lot of
discussion on the pros and cons of RGB vs grayscale, especially with 
RGB partition curves being a more dominant method of printing. 
Threads on this topic sprang up with regularity for a long time.  In
my own testing with BO printing I determined that the resulting prints
varied slightly in contrast and density, but neither was inherently
superior to the other.  Since Grayscale images were 1/3 as big as RGB
it was an easy choice for me.  Over time those threads disappeared and
other trends took their place.  I guess it seemed to me that the
subject had long since ceased to be an issue and using grayscale had
become part of accepted wisdom, so I was a bit surprised by your post.

The point of this is just to underscore what Steve said and that you
need to pick one way of doing it and stick with it.  There are enough
other variables happening, why add another.  And it's quite likely
that with ABW and color inks involved, the differences between them
will be greater than they were with BO printing.  You probably don't
need that headache.

Back to your original problem, it seems that several things were
changed at once, so it's hard to tell which one was most responsible
for the differences.  That's one thing I've learned: when
experimenting, change one thing at a time.  

As for differences in ink batches, I've already learned that ABW
settings aren't carved in stone.  I can expect to make minute changes
from time to time.  I now keep a short memo in each image with the ABW
settings listed, and I keep brief notes about any changes made (it's
possible that subsequent ink changes might require going back to a
previous setting).  

For paper differences, I use image adjustment curves to compensate for
that.  I save them with the image (un-flattened), with each curve
labelled for its paper name.  It not unusual to have to tweak one of
these for a new batch of paper.  It's just a fact of life.  For
example, for an image I print in different sizes I have separate
curves for 8.5x11 and 13x19 versions of the same paper, because my
current boxes of those are quite different in contrast.

A final thought: I keep a small master print of each image so I can
compare it with later ones to ensure they don't drift over time.  If I
print an image differently I want it to be a conscious choice, not an
unconscious result of changing materials.

I hope these thoughts are helpful.


Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm

Scott,

That is why Epson suggests using their Colorbase program for the R2400 to 
recalibrate your printer when you change to another batch of paper or ink. 
Perfection perhaps, but it might help you.

Bob Frost.

----- Original Message ----- 
From: "Scott Jones" <peanutdogs@...>
My latest print just a few minutes ago, came out decidedly with a green
cast. I seem to have lost all the modest warmth that I would usually
get with ABW +2/+2 on the toning wheel.

Discouraging.....