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help with resolution.

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September 16, 2004 3:43:55 AM

Archived from groups: comp.periphs.printers (More info?)

Hi all I am confused.

I am happy with DPI, pixels and so on.

However can someone explaing the following.

1. My printer has a max resolution of 1440 dpi.

If I have a digital image of 2880 x 1500, it must only be 2 inches wide when
printed at highest res.

2. Why do they say that 300dpi gives a good quality photo print, if my
resolution was 2400 pixels wide, it would be only 8 inches wide, yet all the
magazines say that this will give me decent a3 print.

HELP!!!

More about : resolution

September 16, 2004 3:47:18 AM

Archived from groups: comp.periphs.printers (More info?)

"George" <georgezx9@hotmail.co.uk> wrote in message
news:%s42d.1049$hZ3.568@fe2.news.blueyonder.co.uk...
> Hi all I am confused.
>
> I am happy with DPI, pixels and so on.
>
> However can someone explaing the following.
>
> 1. My printer has a max resolution of 1440 dpi.
>
> If I have a digital image of 2880 x 1500, it must only be 2 inches wide
when
> printed at highest res.
>
> 2. Why do they say that 300dpi gives a good quality photo print, if my
> resolution was 2400 pixels wide, it would be only 8 inches wide, yet all
the
> magazines say that this will give me decent a3 print.
>
> HELP!!!
>
>
You are confusing dots per inch (dpi) with pixels per inch (ppi). The
answer is that it takes at least 3 dots (one for each color) to make a pixel
(which contains all colors).
Jim
Anonymous
September 16, 2004 4:50:56 AM

Archived from groups: comp.periphs.printers (More info?)

I'm assuming you have an ink jet, laser, or pin impact printer. You've hit
on a pet peeve of mine. Although it is claimed that the printer has a max
resolution of 1440 dpi it doesn't. What is does have is a printing density
of 1440dpi. Because the size of the dots are bigger than 1/1440" it can't
actually resolve a dot that size. When adjacent dots are printed they
overlap.

The excess of density over resolution is used to advantage to print grey
scale values. The printer prints a few dots in a paper pixel to represent a
light colored pixel in the image. The printer prints many dots in a paper
pixel to represent a dark colored pixel in the image.

Here is an example. If you take your image and print it at 300 pixels per
inch on your printer you will get an image size of 2880/300 by 1500/300
inches or 9.6 by 5 inches. Each pixel of your image is represented on the
paper by a pixel composed of 1440/300 by 1440/300 printer dots or
approximately 5 by 5 dots. The printer can thus produce a grey level on the
paper by printing some of these 5 by 5 dots and not printing the others.
Because the dots are very fine and overlap the eye interprets the paper
image as a grey value.

What you're essentially doing is trading resolution in space for resolution
in printed image density. The bigger the pixels on the paper the wider the
range of grey values each paper pixel can have.

Charles P. Lamb


"George" <georgezx9@hotmail.co.uk> wrote in message
news:%s42d.1049$hZ3.568@fe2.news.blueyonder.co.uk...
> Hi all I am confused.
>
> I am happy with DPI, pixels and so on.
>
> However can someone explaing the following.
>
> 1. My printer has a max resolution of 1440 dpi.
>
> If I have a digital image of 2880 x 1500, it must only be 2 inches wide
when
> printed at highest res.
>
> 2. Why do they say that 300dpi gives a good quality photo print, if my
> resolution was 2400 pixels wide, it would be only 8 inches wide, yet all
the
> magazines say that this will give me decent a3 print.
>
> HELP!!!
>
>
Related resources
Anonymous
September 16, 2004 5:20:04 AM

Archived from groups: comp.periphs.printers (More info?)

George wrote:

> Hi all I am confused.
>
> I am happy with DPI, pixels and so on.
>
> However can someone explaing the following.
>
> 1. My printer has a max resolution of 1440 dpi.
>
> If I have a digital image of 2880 x 1500, it must only be 2 inches wide when
> printed at highest res.
>
> 2. Why do they say that 300dpi gives a good quality photo print, if my
> resolution was 2400 pixels wide, it would be only 8 inches wide, yet all the
> magazines say that this will give me decent a3 print.
>
> HELP!!!
>
>

6x4s are viewed up close, so should be 300dpi.

A3 prints will be viewed from a distance, so 150-200 dpi is more than enough
sharpness.

--
Ben Thomas
Opinions, conclusions, and other information in this message that do not
relate to the official business of my firm shall be understood as neither
given nor endorsed by it.
Anonymous
September 17, 2004 12:43:15 AM

Archived from groups: comp.periphs.printers (More info?)

Ah, the differences between resolution as defined by an image, or a monitor,
or an inkjet printer...

An excellent piece that defines all of these and so much more is located at
http://www.SCANTIPS.com

I highly recommend it

Jeff H

"George" <georgezx9@hotmail.co.uk> wrote in message
news:%s42d.1049$hZ3.568@fe2.news.blueyonder.co.uk...
> Hi all I am confused.
>
> I am happy with DPI, pixels and so on.
>
> However can someone explaing the following.
>
> 1. My printer has a max resolution of 1440 dpi.
>
> If I have a digital image of 2880 x 1500, it must only be 2 inches wide
when
> printed at highest res.
>
> 2. Why do they say that 300dpi gives a good quality photo print, if my
> resolution was 2400 pixels wide, it would be only 8 inches wide, yet all
the
> magazines say that this will give me decent a3 print.
>
> HELP!!!
>
>
Anonymous
September 18, 2004 12:57:26 PM

Archived from groups: comp.periphs.printers (More info?)

Hi George,

Let me try to help. This is a very commonly confusing aspect of printing.

The resolution indicated by an inkjet printer manufacturer is the number
of dots that can be addressed by head position. Often these are made by
using a variety of nozzles or overprinting via several swipes of the head.

That number is speaking about one ink dot (dots per inch). However,
inkjet printers create the hundreds of thousands of colors they can
represent by using a randomized mix of dots of the different colored
inks they have in the cartridges. That used to be simple (four colors,
CMYK). Today there are printers with extra colors and lighter and
darker inks included, but the principle is still the same, to create
photographic color you need many more colors than the inks themselves
can produce. In order to accomplish this, the printer uses different
percentages of dots of different colors to represent a color. Since the
dots are so small and packed so closely, to the human eye they appears
as a section of solid color, when actually made up of many dots of
several colors.

A certain shade may require a matrix of 9 or even more dots to create
the illusion of one pixel color from your monitor screen.

The average drug store variety photo print (4" x 6") has the equivalent
of about 200 dpi of resolution. A custom photo print may be 250-300 dpi
equivalent resolution.

Most printer manufacturers suggest something between 240-360 dpi as a
source file at final print size. So an 8" x 10" print should probably
have a pixel dimension something between 1920 x 2400 and 2880 x 3600
pixels. With a good printer driver and careful use of unsharp masking
even a 150-200 dpi source file can produce a decent result, especially
if it will be viewed at several feet away.

The best approach is to experiment and find the sweet spot for your
application and equipment. In terms of what printing resolution mode to
use, it depends upon the paper and inks you use, and the subject matter
of the image, but you will probably find that the improvement once you
get to 1200 or 1440 dpi, is not noticeably improved by going higher, yet
the printing time becomes considerably longer.

Art

George wrote:

> Hi all I am confused.
>
> I am happy with DPI, pixels and so on.
>
> However can someone explaing the following.
>
> 1. My printer has a max resolution of 1440 dpi.
>
> If I have a digital image of 2880 x 1500, it must only be 2 inches wide when
> printed at highest res.
>
> 2. Why do they say that 300dpi gives a good quality photo print, if my
> resolution was 2400 pixels wide, it would be only 8 inches wide, yet all the
> magazines say that this will give me decent a3 print.
>
> HELP!!!
>
>
!