Inkjet printer best results. RIP software ?

[Joseph Chamberlain, D.D.S.]

Dear members:


This is my first post to the group and I don't have much experience with
printing technologies so I apologize if my questions seem rather basic.

Although I have been using inkjet photo printers for a while, I have began
to question whether I am really getting the best results I can for my
printed photos. They look very good and in fact rival anything I ever got
from film and traditional chemical developing techniques. However, I feel
that with the current digital technology and the quality of the files I work
with the prints could (and should) look better.

I work with two Epson printers - a Stylus Photo R1800 (resolution of 5760 x
1440) and a Stylus Photo 900 (resolution of 5760 x 720). The printer driver
provides options that vary according to the paper type selected but one has
no control over the resolution used for printing. With this in mind, here
are my questions:

1. I work with files generated by a Canon EOS 1Ds Mark II digital SLR that
produces images with a resolution of 4992 x 3328. When printing a 8" x 10"
photo these files should allow a resolution of 499.2 dpi along the longest
dimension and 416 dpi along the shortest dimension. In case the same file is
used to produce a 4" x 6" photo, the resolution would be 832 dpi along the
longest dimension and the same 832 dpi long the shortest dimension.
- How do I know if the printer is using every pixel provided by my file and
placing each pixel on the printed photo instead of just defaulting to the
popular 300 dpi ?
- How can I control the final resolution and force the printer to use all
the available pixels on the image file ?
- In case I choose a resolution that exceeds that of the image file, will
the printer interpolate to create dots on the printed photo that do not
exist in the original image file ?

2. How exactly does RIP software work ? Would I benefit from using a RIP
application and will it give me control over printing resolution and other
features that I can't control with the standard printer driver available for
these printers ?

3. What do you think of PrintFab for the Macintosh ? Is this a good RIP ?
Does it provide increased control over the final print and what kind of
features does it have ? Is there another inexpensive (considering this is
for personal use) RIP you would suggest that would provide me more control
over the printing process and help me improve the quality of my prints ?

In case this is important information, I work with a PowerMac G5 dual
processor 2.0 GHz and it runs OS X 10.4.10 (latest version of Tiger).

Any help will be greatly appreciated.

Thank for your help,

Joseph Chamberlain

 

[Chuck]

In general, you don't-- the printer driver software uses multiple dots to
create a given color and shade.
It may interpolate as it decides to, and if you read the fine print in most
printer specs, direct dot by dot control of the printer is usually limited
to something like 720-760 dots per inch, useing something likr the Epson
printer control language. For finer contol, you would need to have access to
the printer mfrs internal documentation. Postscript and such may give sort
of direct control out to about 600 dpi or so. (I haven't kept up with
postscript revisions, so 600 dpi may no longer be accurate. )
- How do I know if the printer is using every pixel provided by my file and
placing each pixel on the printed photo instead of just defaulting to the
popular 300 dpi ?


You can usually control the final resolution in at least two different
ways--
By setting the printer driver options and/or using an application to set the
size in pixels and inches.
Fir instance, you can usually specify the pixel size of the digital picture
in pixels, such as 1280wx1024h, and specify that it should be printed as a
5"hx7w" picture
- How can I control the final resolution and force the printer to use all
the available pixels on the image file ?

Yes,No, and maybe---
Depends on what the printer driver does.
Older drivers and printers allowed you to set a specific DPI and, as a
result of a badly chosen setting, might print a postage stamp picture on an
8 1/2x11 sheet, or might truncate the sides of a picture so that only the
middle was printed. You might have scale to fit options in a printer driver,
and also in an application designed for graphics and picture processing.
- In case I choose a resolution that exceeds that of the image file, will
the printer interpolate to create dots on the printed photo that do not
exist in the original image file ?

All of this explains why printer drivers usually specify printing quality
instead of dpi.
IE Draft, Normal, Letter Quality, Picture, High Quality, Super High Quality
(names differ between models and mfrs)

On one of my printers, to obtain the highest quality possible, I must select
high quality photo gloss paper, and high quality photo printing to obtain
what ever the printer driver considers the best quality it and the printer
can do.)

Your "Stylus Photo 900 (resolution of 5760 x 720)" might be able to position
a head in increments of 720 or 360 positions per inch. Taking the position
reference to be at the center of a head nozzle pattern, you would have some
number of nozzles around that point. Now move the head by one step or one
720th of an inch. the nozzles still surround the reference position just at
different distances from it. Basically this is how printer mfrs can specify
high numbers such as the 5760x720 number. Usually horizontal head movement
can be more accurate that vertical movement of the paper. However, nozzle
count and spacing plus the movement precision are what generates the
calculated dpi rating. In all likelyhood, a spacing of 5760 dpi will produce
significant dot overlap, and can be (is) utilized by the printer driver to
blend dots together.

If you leave your first born son as a deposit, and sign a non disclosure
agreement in blood, and have a projected application that they like, the
printer mfrs will consider allowing access to the internal documentation
that describes in detail how a specific printer driver or family of drivers
work. That's the only way I know to get the information that actually begins
to answer your questions in detail.