Is this reasonable quality for a 600 DPI printer?

[metremeter]

Hi,

I've been testing a 600 DPI large-scale printer (HP 3000CP), but my
boss is disappointed with the quality of the printouts so far. They
remind me of my late-1990s Canon BJC printer (which was apparently 720
x 360 DPI, and from what I remember noticably coarser than the one I
replaced it with four or five years back).

The printer output is the image in the centre here:-
http://home.freeuk.com/misacham/temp/compare.jpg

Please ignore the softness of the image (it's a small pic that was
scaled up and set to 900 DPI). What I'm interested in is the
coarseness of the dots themselves- note particularly the light area of
the girl's hair where you can see individual dots.
For comparison, the picture on the left is scanned from a colour
newspaper picture, and the one on the right is from a DVD cover.

I appreciate that this printer is itself a few years old, and intended
for large scale work where such details might not be so important,
but... is this "600 DPI" quality?

- MM

 

[me]

On Mon, 24 Mar 2008 12:59:52 -0700 (PDT), in comp.periphs.printers

Hi,

I've been testing a 600 DPI large-scale printer (HP 3000CP), but my
boss is disappointed with the quality of the printouts so far. They
remind me of my late-1990s Canon BJC printer (which was apparently 720
x 360 DPI, and from what I remember noticably coarser than the one I
replaced it with four or five years back).

The printer output is the image in the centre here:-
http://home.freeuk.com/misacham/temp/compare.jpg

Please ignore the softness of the image (it's a small pic that was
scaled up and set to 900 DPI). What I'm interested in is the
coarseness of the dots themselves- note particularly the light area of
the girl's hair where you can see individual dots.
For comparison, the picture on the left is scanned from a colour
newspaper picture, and the one on the right is from a DVD cover.

I appreciate that this printer is itself a few years old, and intended
for large scale work where such details might not be so important,
but... is this "600 DPI" quality?

What paper and driver settings did you use. Inkjet output can be
highly dependent upon both of these. In fact most drivers I've seen
limit output options dependent upon the type of media specified.

IE, the best prints will not be obtained using plain paper.

 

[Arthur Entlich]

The HP 3000CP is a wide carriage inkjet color printer. It is supposed
to print at up to 600 x 600 dpi.

Most printers have drivers which allow you to print in different
resolutions, depending upon the intent of the printout and the substrate
used. Also, some papers types will produce a worse result. Some papers
can congregate, smear or enlarge the dots. Make sure the driver is set
to maximum resolution and you are using the best paper choice for that
model printer to test it.

Without knowing what paper was used it is difficult to know if this
image is normal or not. If you are printing at 600 dpi, that certainly
should supply you with a reasonable result.

I believe this printer is a 4 color model, meaning it doesn't use the
low dye load colors (light cyan, light magenta), so the dots are all the
same density of color. Also, the size of the dot determines how smooth
the gradients, especially in lighter areas will look.

In general, with small dots and low dye load colors, 600 dpi should give
close to photographic results. Keep in mind, however, that this printer
is something like 54" wide, so it is not designed to produce small
prints that will be scrutinized very closely. Keep in mind that higher
resolution often means larger file sizes, slower spooling and printing,
and sometimes use of more ink.

Other brands of wide carriage printers usually use 720-1440 dpi.

Art

 

[tomm42]

Hi,

I've been testing a 600 DPI large-scale printer (HP 3000CP), but my
boss is disappointed with the quality of the printouts so far. They
remind me of my late-1990s Canon BJC printer (which was apparently 720
x 360 DPI, and from what I remember noticably coarser than the one I
replaced it with four or five years back).

The printer output is the image in the centre here:-http://home.freeuk.com/misacham/temp/compare.jpg

Please ignore the softness of the image (it's a small pic that was
scaled up and set to 900 DPI). What I'm interested in is the
coarseness of the dots themselves- note particularly the light area of
the girl's hair where you can see individual dots.
For comparison, the picture on the left is scanned from a colour
newspaper picture, and the one on the right is from a DVD cover.

I appreciate that this printer is itself a few years old, and intended
for large scale work where such details might not be so important,
but... is this "600 DPI" quality?

- MM

First of all the 3000CP is more of a plotter than a LF printer, maybe
capable of good work, and it may not be. This is an old model too
certainly not something to judge the current state of inkjet printers
by. Also most inkjet printers want images of 300-600 ppi, 900ppi is
over kill and if you are going to any size at 900ppi you may induce
enlargement artifacts. The latest printers from HP, Epson and Canon
give continuous tone prints that are in many ways superior to
traditional chemical based photography, of course that is a subjective
observation. Some guidelines

While the printer may say 600dpi or 1200 or even 2400dpi, that is how
it puts down ink, not what your the res of your images, HP and Canon
want 300 or 600 ppi images, Epson 360 or 720ppi images. You will get a
tiny bit more visible res in your image by using the higher res but in
general most prints are done at 300 or 360ppi. Your driver will
increase or reduce the res to 600ppi (or 720), this has a lot to do
with image quality too.

No enlargement is lossless, while digital enlarges much nicer than
optical methods, push it too far and you get artifacts, that includes
going to 900ppi for printing resolution. A 2X enlargement (8x12 to
16x24) works very well in digital.

Work in a 16bit workflow while editing, maintains color and sharpness
better, dropping down to 8 bit for printing is fine.

Tom

 

[metremeter]

What paper and driver settings did you use. Inkjet output can be
highly dependent upon both of these. In fact most drivers I've seen
limit output options dependent upon the type of media specified.

IE, the best prints will not be obtained using plain paper.

The paper was a roll of 230gsm glossy paper. I used the "coated paper"
setting, and from a choice of "photo", "productivity" and "economy"
settings I chose "photo". (There are lights on the front of the
printer for these three settings, suggesting that they are fixed,
although they could also be "relative" quality settings that vary
according to the paper used. However, changing to "high-gloss photo"
does not seem to change things much).

I've tried both manual and automatic colour, and done both large and
small-scale printouts. I used various paper-size settings, which I
assume have no effect on the print quality in themselves.

- MM

 

[metremeter]

Make sure the driver is set
to maximum resolution and you are using the best paper choice for that
model printer to test it.

I'm using 230gsm glossy paper, and I selected this type and "photo
quality" for the printout.

Without knowing what paper was used it is difficult to know if this
image is normal or not. If you are printing at 600 dpi, that certainly
should supply you with a reasonable result.

Yes, but the question is, what's reasonable here?
Seriously, in a way that was the question I was asking(!)

In general, with small dots and low dye load colors, 600 dpi should give
close to photographic results.

I wouldn't describe the results as "photographic" at the viewing
distance for (e.g.) a 6 x 4 inch photo print; it's noticably coarse.
On the other hand...

Keep in mind, however, that this printer
is something like 54" wide, so it is not designed to produce small
prints that will be scrutinized very closely.

That was why I (personally) thought the quality was acceptable for
large posters, although apparently my boss wants to do smaller stuff
with it as well.

Thanks for the feedback,

- MM

 

[metremeter]

This is an old model too
certainly not something to judge the current state of inkjet printers
by.

I realise that; it's of the same vintage as my old Canon BJC, and the
quality is similar (which is to say, nowhere near as fine as current
desktop printers)- but then this printer would have been far more
expensive when bought new(!)

While the printer may say 600dpi or 1200 or even 2400dpi, that is how
it puts down ink, not what your the res of your images

Yes, I realise that dpi != ppi; even though it was probably overkill,
the 600 dpi was chosen so that there was no way the quality of the
photo would be dragging down the quality of the output (this is just
the testing stage).

No enlargement is lossless, while digital enlarges much nicer than
optical methods, push it too far and you get artifacts, that includes
going to 900ppi for printing resolution.

The artifacts I was concerned with were the printing dots, not
blurriness caused by upscaling, enlargement of JPEG artifacts, etc.

Thanks for the rest of the info too, BTW.

- MM

 

[Arthur Entlich]

It seems that one of my postings got lost along the way, so I'll try to
repeat some of it.


There are a number of things that determine print quality and how
photographic the end result is.

Before getting to the printer, the quality of the source material and
how it is processed... Low resolution, highly lossy Jpeg compression,
over processing causing posterization, or low color bit depth, among
other things, can ruin the data.

The rasterization and spooling process done by poor software can further
damage data.

However, once it gets to the printer, other problems can be added.


Using too low a dot resolution

Using the wrong paper type. Just because you used a glossy 230 gsm
paper doesn't mean the correct type of the inkjet technology was used.
A wrong paper formulation can cause either massive bleeding and dot
gain, or clumping and reticulation of the inks, as well as very slow drying.

Inkjet printers resolve diminishing dots in light areas by one of two
methods, and this printer in discussion doesn't do one, and may
incorporate the other poorly.

To diminish the clarity of dots in light areas, the printer may use a
low dye load ink (light C and M), or if not, it can use a very small dot
(as small as one picolitre volume). Some older printers had minimum
drop size of as much as 11-18 picolitre. Epson heads has a design
technology that allows them to produce numerous drop sizes from the same
nozzles. To my knowledge all thermal head designs require separate
nozzles for each drop size.

Lastly, almost all wide carriage printers use a lower resolution pattern
dot and raster, usually 1/2 to 1/4th of a desktop printer, because the
assumption is that the image will be larger and therefore viewed at a
greater distance. For images below letter size, it usually is not
worthwhile to use a wide carriage professional printer. They are
designed to print more rapidly, and since the files will tend to be
large already, to be able to work at a lower resolution to reduce the
size of the files. Tis saves time in rasterization/spooling processing
and storage, and speeds up the printing process.

Art

 

[metremeter]

It seems that one of my postings got lost along the way, so I'll try to
repeat some of it.

I think it *did* get posted if it's the March 25 one, but there's some
interesting extra detail in this one anyway.

Using too low a dot resolution

Yep; though as far as I can tell I was using the highest-quality
settings here- it was set to "photo" in the driver (and indicated as
such on the front of the machine).

Using the wrong paper type. Just because you used a glossy 230 gsm
paper doesn't mean the correct type of the inkjet technology was used.
A wrong paper formulation can cause either massive bleeding and dot
gain, or clumping and reticulation of the inks, as well as very slow drying.

I didn't see any obvious dot gain (image was if anything a bit light)
nor have any problems with drying.

To diminish the clarity of dots in light areas, the printer may use a
low dye load ink (light C and M),

Which (as you implied) this printer definitely doesn't do; though
given its age, I'm not surprised.

Lastly, almost all wide carriage printers use a lower resolution pattern
dot and raster, usually 1/2 to 1/4th of a desktop printer, because the
assumption is that the image will be larger and therefore viewed at a
greater distance.

I think you put your finger on it there! Even though it was probably
expensive when new, it's still a ten-year old printer designed for
printing large posters to be viewed from some distance, and as the
dots are no worse than my old desktop BJC of the same vintage, I doubt
that the "coarse" dots were even an issue at the time.

To be honest, I think too much was just being expected of this
printer.

For images below letter size, it usually is not
worthwhile to use a wide carriage professional printer. They are
designed to print more rapidly, and since the files will tend to be
large already, to be able to work at a lower resolution to reduce the
size of the files. Tis saves time in rasterization/spooling processing
and storage, and speeds up the printing process.

Yes; I'd shudder to imagine how much memory would be required to print
a 600 ppi (not dpi) image at the full size this printer is capable of
(it's 1.4m or so wide). Even with todays' memory prices, it'd need
countless gigs. And at late-1990s prices... forget it! Don't know how
much memory it has, but printing a 600 ppi test image at somewhere
between A2 and A3 size (not huge) caused it to run out of internal
memory and forced me to shift the load onto the PC.

Anyway, useful reply- thank you!

- MM