Digital BW, The Print

First of all I'd like to say that this is a great group! I have 
learned so much about B&W digi-printing. I will be having a solo 
exhibition at a major corporate center next year where I will be 
displaying my B&W prints. With your help, my prints should be 
outstanding. Now I have a few questions for the group:

What is the reason that you convert an RGB image to grayscale then 
back again for B&W printing purposes? Is this only for scanned negs 
and prints or would it be right for digital RAW images also?

I have PS CS and am doing all post-prOcessing in 16 bit. Is it 
required that I convert to 8 bit prior to printing or will my printer 
(Ep 1280) print at 16 bits?

And what is "Dot Gain" and how do I work with it within PS for better 
printing?

Thanks
Terry Lyons
www.TLphoto.net

> From: Terry [mailto:teelions@...]
>
> What is the reason that you convert an RGB image to grayscale then
> back again for B&W printing purposes? Is this only for scanned negs
> and prints or would it be right for digital RAW images also?

If you're printing B&W using color inks, converting back to RGB allows you
to use the color balance sliders to adjust the overall tone. Also, I've
found that the Epson 2200 printed with a horrible color cast, if I printed a
grayscale image with color inks, but printed correctly if I converted to RGB
first--but I suspect that was just a bug in that particular driver version.

> I have PS CS and am doing all post-prOcessing in 16 bit. Is it
> required that I convert to 8 bit prior to printing or will my printer
> (Ep 1280) print at 16 bits?

The image will automatically be reduced to 8bpc on the way to the printer
driver.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...

* -----Original Message-----
* From: Terry [mailto:teelions@...] 
* Sent: Wednesday, November 05, 2003 2:02 PM
* To: DigitalBlackandWhiteThePrint@yahoogroups.com
* Subject: [Digital BW] Semi-Newbie Questions
* 
* 
* First of all I'd like to say that this is a great group! I have 
* learned so much about B&W digi-printing. I will be having a solo 
* exhibition at a major corporate center next year where I will be 
* displaying my B&W prints. With your help, my prints should be 
* outstanding. Now I have a few questions for the group:
* 
* What is the reason that you convert an RGB image to grayscale then 
* back again for B&W printing purposes? Is this only for scanned negs 
* and prints or would it be right for digital RAW images also?

Terry,

Whether you convert to or from RGB depends completely on the printer, inks,
workflow and driver you are using. If you are printing with the Piezo or R9
driver everything has to wind up in grayscale. If you are using Paul Roark's
RGB separation curves you need to switch to RGB in order for that to work.
The various different RIPs with color ink sets will requite RGB files as
well. The is no right answer here. Depends upon how you are printing and
what you started with in digital form.
* 
* I have PS CS and am doing all post-prOcessing in 16 bit. Is it 
* required that I convert to 8 bit prior to printing or will my printer 
* (Ep 1280) print at 16 bits?

I believe just about all the workflows will allow you to print directly from
16-bit mode but once again it depends upon what you have chosen to work
with.
* 
* And what is "Dot Gain" and how do I work with it within PS for better 
* printing?

Dot Gain is a term from offset lithography printing and applies to inkjet
printing to the extend that drops of ink spread on the paper. It is not
something you really need to know for B&W digital printing. If you want a
technical explanation check out:

http://www.tintas.com/tech_info/what_is_dot_gain.html  

Dot % is a related concept used to compare a shade of a color, in our case
gray, in terms of 100%  and paper white. It only comes up here in terms of
creating custom dot gain curves for proofing your images on screen to get a
better screen to print match. You need an instrument like a densitometer or
photospectrometer to measure and/or calculate Dot % percentages but you can
also use your own eyes to get good results.

In the Files section see:

Files > Image Processing > Matching Your Monitor view to Your Prints.pdf

And 

Files > Image Processing > Simple Dot Percent.xls 

Martin Wesley
http://www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html
http://www.borderless-photos.de/guests.html