Will this ever change?

[Charles Moir]

Yes but magazine printing is not the same as large format printing for the sign industry.

Oh come on, you not seriously be suggesting that you need better quality than in a glossy magazine, on a side of a bus or van.

The point remains. You do not need any more than 150 dpi (ppi) for almost any work, even the highest quality magazine work, and certainly not poster work.

[steve.ledger]

Yes.

And again, 'poster' work is not the same as 'signage' work.

[MEB]

So to print the single pixel (that on a screen had a color depth of 16 million colors) many tiny drops of ink (or dots) are required. To accurately show the color, it may require as many as 16 drops (dots) of ink. (e.g. 4 red, 3 blue, 5 green, 2 yellow and 2 black)
So do the math here:
150dpi x 16 droplets = 2400 REAL dots per inch (dpi) on the media

You´re saying that each DOT from (dpi) is composed of up to 16 ink dropplets, and so the value anounced by print manufacturers is 16 x (the real dpi capacity of the printer) - usually 150 an thus the 2400 announced.
Have i understood it correctly?


A real example:
My Canon printer (Pixma iP4300) in their specs has:
---------------------------------------------------------------------
Printing Resolution (dpi): 9600(horizontal)* x 2400 (vertical)

* Ink dropplets can be placed with a pitch of 1/9600 inch ar minimum.
---------------------------------------------------------------------

It uses 4 inks (well 5 but two of them are black).
This means it has 600dpi (max horizontal resolution x 150dpi (max vertical resolution)?
Since when we specify the dpi for our image it´s a single value ( i mean we can´t specify diferent dpi for vertical and horizontal resolution independently for an image) wich dpi setting should i be using in my images to print on my Canon at full quality? 150 dpi or 600 dpi? and why?


Very interesting thread

[steve.ledger]

Yes you are getting the picture (excuse the pun )
Remember *up to 16 droplets* - not always 16 droplets

To quote from some of my notes on the subject (easier than typing in my own words)

"The number of ink drops a printer can put on paper is called the printer resolution dpi. So if a printer has a
resolution of 1200 dpi but requires 16 drops of ink to display a color, the actual resolution is much lower. Since
ink drops are used in both directions (length and width: 16 drops made up of 4 rows of 4 drops), you could say
that the effective resolution would be 1200 divided by 4 (or 300) dpi. Practically this isn't entirely true since
modern inkjet printer can spray tiny ink drops that overlap each other. Roughly you can say that the higher the
printer dpi, the higher the print quality, but it also depends on how the printer forms the dots on paper.
But the general picture is that since a printer can't display all colors directly, it needs many more dots to create
the illusion of that color. Therefore the dpi in printer specifications should not be used for calculating file sizes."

As Charles rightly says, it's an 'Old Chesnut'...

Some excellent resources on the web exists. Simply google 'The DPI myth' for example..

[jnerf]

I understand what you are saying Charles, but that wasn't the answer to my question, why the 16384 pixel limitation, all the other software like corel, adobe does not have this?

Also discussing resolution, it also matters what format you export out,
if you have photos, mixed with text and graphics,
many companies save out to jpg, but jpg is lossy compression,
which means you lose detail, when enlarged,
when saved out to a 300 to 600 dpi tiff from vector, if you have to enlarge it no problem
because a tiff, is lossless compression.

I will argue the point that a flattened graphic is a flattened
graphic, jpg no difference in tiff same size, baloney!

even saving a graphic to something small at 150 dpi,
will not be as clear as 600 dpi,

I print everyday, and I can see the difference
on printed vinyl, and so can our customers
our clarity stands out above the rest in our area.

By the way is anyone printing directly to their large format printer
from Xara, we have a roland 540-v and would like to know how
if anybody is doing this already.

thanks
jnerf

[MEB]

Some excellent resources on the web exists. Simply google 'The DPI myth' for example..

Hum i´m still misleading some things. My previous question (regarding vertical and horizontal resolution) doesn´t make sense.
Thank´s for the tip on google Steve. Seems i have some homework to do...

[BobInce]

We DO super-sample when scaling images up

That's not super-sampling (which is only a issue to do with scaling down) and I'm not talking about images in particular.

Xtreme (all the way back to ArtWorks) performs anti-aliasing on each object separately and then composites them on a pixel level. So if you make a 1px red square, then overlay a white half-square on the left and a black half-square on the right, the red shows through, even though when you zoom it up you only see the white and black. Similarly, a red anti-aliased object on top of a black anti-aliased object of the same shape will have a dark fringe around the edge.

Saving as non-anti-aliased at a larger resolution and then resizing downwards solves the problem. Saving as anti-aliased super-sampled also reduces the problem whilst requiring less super-sampling to keep the anti-aliasing smooth.

Super-sampling is essential for the icon work I do and it would be a handy option to save having to export-and-resize in two separate steps.

Xtreme 4's VHQ option reduces the need for super-sampling because, indeed, zoomed-down images are now scaled nicely. But there are still applications.

And as I've just described 16,000 pixel limitation is NOT a limitation for all reasonable and practical purposes

I think you're being a little over-defensive here. Sure, people export for print at higher resolutions than they need to, but that's hardly the only application for very wide or tall images. (eg. I've gone well over 16384 for splicing together webcomic images.)

With Xara becoming more and more competent at editing bitmaps, it would be nice to see these limitations lifted, since from the user end they look fairly arbitrary.

[SignPig]

By the way is anyone printing directly to their large format printer
from Xara, we have a roland 540-v and would like to know how
if anybody is doing this already.

I have Roland VP-540 but I don't print directly from Xara, I export to the RIP and let it handle the printing and cutting.

Charles, you are indeed correct in what you are saying but I think you are completely missing the point. I make signs and prefer to draw to actual size rather than scale down. Not all sign designs and vehicle wrap designs are made up of or contain bitmaps, vectors produce the best files and Xara is fantastic for vectors so it makes more sense to layout graphics on a car outline at actual size rather than to scale down at the design stage and then scale up again at the print stage. With vector graphics the file size doesn't increase with the drawing size. Trust me, much bigger page sizes would make Xara much more appealing to sign makers.

Pleeeeeeease.