color laser memory requirements - Help Please

[Richard Galli]

I am trying to choose between three color laser/LED printers. I have
obtained print samples for each and am close to making a decision.

All three come with 256 megs of memory installed. Two allow upgrading to
one gig of memory total. But one -- the printer producing the sharpest
image -- allows only 512 megs total.

All three allow banner printing up to (approximately) 12" X 48" --

-- but the question is whether the printer with only 512 megs total
capacity will be able to handle a graphics-intensive document that size.

The strange thing is that the two printers with higher memory capacity
print at a maximum resolution (1200X600) that is less than the 1200X1200
true dpi of the printer with the lower capacity. Go figure.

Maybe the machine with true dpi resolution has to spend less memory on
interpolation or "resolution enhancement" but that's a guess.

At any rate, can anyone please shed light on whether I am likely to
suffer out-of-memory (page overrun) problems if printing graphics to
banner size paper (12"X48") with a maximum memory capacity of 512 megs?

I appreciate the help.


Richard Galli
http://www.richardgalli.com

 

[Don Phillipson]

-- but the question is whether the printer with only 512 megs total
capacity will be able to handle a graphics-intensive document that size.

This question can be answered by the printer's vendor or
manufacturer. The answer is almost certainly Yes because
printer memory does not limit the capacity of the printer to
print a document, only the speed of transfer. The source file is composed
by software before printing, and then sent to the printer, buffered
en route by the operating system. Printer memory governs the
speed at which the printer can empty the computer's buffer, i.e.
determines how soon the computer can finish this particular
task and be redirected to a different task.

If this account is wrong for some printers, the vendor
should be able to tell you.

 

[Arthur Entlich]

I'm sorry I can't answer your question, although I suspect 512K will not
be adequate to print a 12" x 48" banner image at maximum resolution,
unless oem type of compression method is used, or it is somehow able to
re-rasterize on the fly as it is printing.

Do you, or does anyone know just how these new banner printing models
operate? Do they work rapidly enough to download sections of the raster
from the computer on the fly, as they are printing, clearing already
used portions of the raster?

Also, how does the banner quality look? Is it available at maximum
resolution, is there an breakup or match up problem? Doe sit print the
whole image at once, or does it do it in segments stopping between them?
When looking at the end result, can you see any "splicing"?

I'd like to find out more about these models also. Anyone have a good
URL on any of them?

Thanks

Art

 

[Arthur Entlich]

Actually, as I understand it, although your explanation may be correct
for dot matrix, inkjet and maybe solid wax printers (which print line by
line with a movable head), laser printers do not generally work as you
have described. These banner printers may use some type of purge and
upload method, if they can be either slowed down or stopped during the
printing process, I still need to research more about this.

With laser printers typically an image is spooled and rasterized either
on your computer's hard drive or within the printer, depending upon the
printer model, but the raster is then transferred fully to the printer
and stored in its memory. The printing process on standard laser
printers is way too fast to allow it to wait for a download of
information from another source. Large printer memory can be used to
store more than one page of information, freeing up the computer processor.

If laser printers worked as you describe they would suffer from buffer
underruns all the time, especially if the computer was busy with
something intensive.

You probably noticed that there is a time gap between when you hit the
print button and when a laser printer begins to print. That is both the
spooling time, and then, the download time for the document to the
printer memory.

You may also notice that inkjet printers can have as little as 16K
buffers, although today most have more (64K - 256K or more). This is
because they only need to store a couple of lines of information at a time.

Even black and white laser printers usually come with minimum of 16 megs
and often more.

Art

 

[Tony]

This question can be answered by the printer's vendor or
manufacturer. The answer is almost certainly Yes because
printer memory does not limit the capacity of the printer to
print a document, only the speed of transfer. The source file is composed
by software before printing, and then sent to the printer, buffered
en route by the operating system. Printer memory governs the
speed at which the printer can empty the computer's buffer, i.e.
determines how soon the computer can finish this particular
task and be redirected to a different task.

If this account is wrong for some printers, the vendor
should be able to tell you.

Don I do not believe this is entirely correct. The majority of lasers require
the entire image to be in memory before they start to print because their
mechanical inertia prevents them from slowing down or stopping whilst their
memory is refreshed without some sort of visible blemish on the printout. I do
not know of any laser or LED printer that slows down during printing, I do know
of some that can operate at different speeds but the speed is constant
throughout the printing operation. Therefore I believe that the printer memory
is the most limiting factor in determining what can be printed. This does not
apply to inkjets.
Tony

 

[Todd H.]

I am trying to choose between three color laser/LED printers. I have
obtained print samples for each and am close to making a decision.

All three come with 256 megs of memory installed. Two allow upgrading
to one gig of memory total. But one -- the printer producing the
sharpest image -- allows only 512 megs total.

All three allow banner printing up to (approximately) 12" X 48" --

-- but the question is whether the printer with only 512 megs total
capacity will be able to handle a graphics-intensive document that
size.

Hard to say. How much memory is required is strongly dependendent on
the printer's implementation of the print engine.

It'd be better to redirect your question and including the 3 candidate
models that you're pondering and seeing if anyone with those printers
can/have achieve what you're attempting with the memory they've got.

 

[Todd H.]

Don I do not believe this is entirely correct. The majority of lasers require
the entire image to be in memory before they start to print because their
mechanical inertia prevents them from slowing down or stopping whilst their
memory is refreshed without some sort of visible blemish on the printout. I do
not know of any laser or LED printer that slows down during printing, I do know
of some that can operate at different speeds but the speed is constant
throughout the printing operation. Therefore I believe that the printer memory
is the most limiting factor in determining what can be printed. This does not
apply to inkjets.

I do not believe this applies to all laser printer implementations
either.

For example, I have an Okidata C5150n color LED printer with just 32Mb
of RAM. You wouldn't think it could print hardly anything with just
that much, but given its proprietary printer language and its
cooperation with its windows driver for rendering... it can print
remarkably complex goodies with that meager amount of memory.

I don't currently know enough about their implementation to say why,
but I can vouch for the fact that it has printed out some extremely
dense and complex graphics for me.

 

[Tony]

I do not believe this applies to all laser printer implementations
either.

For example, I have an Okidata C5150n color LED printer with just 32Mb
of RAM. You wouldn't think it could print hardly anything with just
that much, but given its proprietary printer language and its
cooperation with its windows driver for rendering... it can print
remarkably complex goodies with that meager amount of memory.

I don't currently know enough about their implementation to say why,
but I can vouch for the fact that it has printed out some extremely
dense and complex graphics for me.

OK, I have a very good contact at OKI and will do some research, it will take a
few days but I will report anything of interest here.
Tony

 

[Arthur Entlich]

I just did a little experiment in Photoshop.

I make a 8.5" x 14" CMYK blank image at 1200, 600 and 300 dpi to see how
large the bitmap is.

The results were: 1200 dpi - ~654 megs, 600 dpi ~164 megs, and 300 dpi
~41 megs

So, obviously, there is some type of major compression through the
vector or raster process.

Art

 

[Warren Block]

I am trying to choose between three color laser/LED printers. I have
obtained print samples for each and am close to making a decision.

All three come with 256 megs of memory installed. Two allow upgrading to
one gig of memory total. But one -- the printer producing the sharpest
image -- allows only 512 megs total.

All three allow banner printing up to (approximately) 12" X 48" --

-- but the question is whether the printer with only 512 megs total
capacity will be able to handle a graphics-intensive document that size.

For 12" x 48" at 1200 DPI:

(12 * 1200) * (48 * 1200) = 829,440,000 pixels per bitmap

Since color lasers use four colors, you'll have four bitmaps. Divide by
8 for bits per byte:

(829,440,000 * 4) / 8 = 414,720,000 bytes, or 395 megabytes.

That's worst-case. In reality, I'd expect current printers to store
bitmaps in compressed form. Photos would not compress much, but
business graphics could be reduced by half or more.

 

[me]

I am trying to choose between three color laser/LED printers. I have
obtained print samples for each and am close to making a decision.

All three come with 256 megs of memory installed. Two allow upgrading
to one gig of memory total. But one -- the printer producing the
sharpest image -- allows only 512 megs total.

All three allow banner printing up to (approximately) 12" X 48" --

-- but the question is whether the printer with only 512 megs total
capacity will be able to handle a graphics-intensive document that size.

Its rather difficult to tell from here. My Fiery has 128 meg ram and
the largest documents I have sent through approx 11' x 17' the machine
runs at 400 dpi and 8bit per color and a document that size could have
as many as a dozen 3.6"x2.4" photos (1800x1200 each) plus text. I'm not
sure if any that size were in my last batch of queues but the largest
currently showing in the queue was 24meg, which might have been an A4
(approx 12x8) with 5 1800x1200 pictures.

 

[me]

If laser printers worked as you describe they would suffer from buffer
underruns all the time, especially if the computer was busy with
something intensive.


Even black and white laser printers usually come with minimum of 16
megs and often more.

My aged HP IIp only had .5 meg and would occasionally give out and I
would get about three quarters of a page and then the rest on another
sheet.

 

[me]

That's worst-case. In reality, I'd expect current printers to store
bitmaps in compressed form. Photos would not compress much, but
business graphics could be reduced by half or more.

A bitmap photo will compress quite a lot in a lossless manner, Take a
bmp bitmap and save it as a tiff or gif, both of which are lossless
compressions and you should see a noticeable effect.

Even at a very simple level, a photo description language could go:
I am a picture; I am 1000 pixels wide by 600 pixels deep; Each pixel is
24bit; I will now start at pixel 0,0 and describe until end:
0: abd4c5; 1-356 ff02d2; 357 - 400 4f3ga3

Whereas a bitmap will painstakingly mark out each individual pixel even
if it is the same as the previous one.

 

[Paul Walker]

Hi Warren -

Thanks for doing the math - I've often wondered, but never took the
time to do this. I do hae one caveat - you're assuming that the final
image can be represented with one bit per color per pixel. Some color
printers may use more than 1 bit, to support pixels with variable
intensity. I'm pretty sure that Konica-Minolta does this on at least
one of their models.

Paul Walker

 

[Warren Block]

A bitmap photo will compress quite a lot in a lossless manner, Take a
bmp bitmap and save it as a tiff or gif, both of which are lossless
compressions and you should see a noticeable effect.

Photos don't compress as much because there are relatively few runs of
identical pixels. Business graphics like the inevitable Powerpoint
slides compress very well, because they only use a few colors and there
are large areas of the same color.

Even at a very simple level, a photo description language could go:
I am a picture; I am 1000 pixels wide by 600 pixels deep; Each pixel is
24bit; I will now start at pixel 0,0 and describe until end:
0: abd4c5; 1-356 ff02d2; 357 - 400 4f3ga3

That's RLE (run-length encoding) compression, which I described above.
It doesn't work very well with most photos because of shading
variations. I'd expect most color lasers to store the individual CYMK
bitplanes separately. They need to be separated anyway because each
color is printed at a different time, but it's probably easier to find
compressable repeating bits in a single-bit deep bitplane than in a
4-bit combination, or 24-bit as in your example.

Whereas a bitmap will painstakingly mark out each individual pixel even
if it is the same as the previous one.

At some point, the printer mechanism needs to see a bitmap. However,
the printer CPU can keep the bitmap stored in a compressed form
internally up until it's time to do the actual printing.

 

[Warren Block]

Thanks for doing the math - I've often wondered, but never took the
time to do this. I do hae one caveat - you're assuming that the final
image can be represented with one bit per color per pixel. Some color
printers may use more than 1 bit, to support pixels with variable
intensity. I'm pretty sure that Konica-Minolta does this on at least
one of their models.

It's probably possible by varying the size of the pixel using something
like HP's "RET" modulation. It would be interesting to see how many
usable levels of intensity that provides.

 

[me]

Hi Warren -

Thanks for doing the math - I've often wondered, but never took the
time to do this. I do hae one caveat - you're assuming that the final
image can be represented with one bit per color per pixel. Some color
printers may use more than 1 bit, to support pixels with variable
intensity. I'm pretty sure that Konica-Minolta does this on at least
one of their models.

I think some of theirs have a 4 bit depth on each colour. Canon's CLC
range uses an 8 bit depth, whereas their IRC's seem to be 4 bit, as I
believe are the Ricoh printers, as opposed to their copiers. I haven't
been able to work out the situation regarding the HP8500/CP660.

 

[me]

It's probably possible by varying the size of the pixel using something
like HP's "RET" modulation. It would be interesting to see how many
usable levels of intensity that provides.

The high end machines tend to go for a toner and developer process to
genuinely vary intensity.

Now, I did do some A3 (approx 11x17") printing yesterday, and those
pages came out at 41meg, so on that basis 256 meg should be more than
sufficient for a 4 foot banner print.

 

[Tony]

OK, I have a very good contact at OKI and will do some research, it will take
a
few days but I will report anything of interest here.
Tony

OK, finally I was able to get some information which is pretty well what I
expected.
The OKI printers, in common with all laser/LED printers so far as I'm aware,
can only print what is in their memory (or on a built in hard drive). The use
of PCL can dramatically reduce the size of an image but the image has to be
resident in the printer before the printing starts.
Tony

 

[Todd H.]

OK, finally I was able to get some information which is pretty well what I
expected.
The OKI printers, in common with all laser/LED printers so far as I'm aware,
can only print what is in their memory (or on a built in hard drive). The use
of PCL can dramatically reduce the size of an image but the image has to be
resident in the printer before the printing starts.
Tony

Cool. Good to know. I wonder what example image might outrun the
memory I have on this thing. Hrmmm.