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printing resolution

 
 
ivan danicic
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      11-01-2004
Hello All, I open a picture in psp7 and click on 'image info'.
It displays :
Image: dimension 3072x2048 pixels.
6.000x4.000 inches.
pixels per inch 512.

Where does this information come from? I know about the dimension but not
about 6x4 (or equivalently 512).
I have not asked the program for any resolution so far.
Any comments gratefully received.
Ivan



 
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Fred Hiltz
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      11-01-2004
ivan danicic wrote:
> Hello All, I open a picture in psp7 and click on 'image info'.
> It displays :
> Image: dimension 3072x2048 pixels.
> 6.000x4.000 inches.
> pixels per inch 512.
>
> Where does this information come from? I know about the dimension
> but not about 6x4 (or equivalently 512). I have not asked the
> program for any resolution so far.


Hi Ivan. Some file formats carry the resolution set by whatever app
wrote the file, but many do not. If the file does not say, PSP uses
the default resolution that you set with File Preferences > General
Program Preferences > Rulers and Units.
--
Fred Hiltz, fhiltz at yahoo dot com

 
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Mike Williams
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      11-01-2004
Wasn't it ivan danicic who wrote:
>Hello All, I open a picture in psp7 and click on 'image info'.
>It displays :
>Image: dimension 3072x2048 pixels.
> 6.000x4.000 inches.
> pixels per inch 512.
>
>Where does this information come from? I know about the dimension but not
>about 6x4 (or equivalently 512).
>I have not asked the program for any resolution so far.


PSP7 always considers an image to have a physical print size as well as
a dimension in pixels. It's not used very much except when you print the
image and don't specify anything that overrides it.

When you create a new image, you enter the resolution and can either
enter the dimension in pixels or the print size in inches or
centimetres. So if you ask PSP7 to create an image that is 3072x2048
pixels and has a resolution of 512 pixels/inch then it will calculate
the print size in inches for you.

Some image file formats store the print resolution, and PSP7 will read
the value when it opens an existing image.

Some image formats don't have the ability to store the resolution. When
PSP7 loads such an image it will use the default resolution.

You can change the default resolution under File => Preferences =>
General Preferences => Rulers and Units.

You can change the print size/resolution of an image without changing
its dimension with Image => Resize by selecting the "Actual/Print Size"
button.

--
Mike Williams
Gentleman of Leisure
 
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Alan Meyer
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      11-01-2004
"ivan danicic" <(E-Mail Removed)> wrote in message
news:h0qhd.27845$(E-Mail Removed) k...
> Hello All, I open a picture in psp7 and click on 'image info'.
> It displays :
> Image: dimension 3072x2048 pixels.
> 6.000x4.000 inches.
> pixels per inch 512.
>
> Where does this information come from? I know about the dimension but not
> about 6x4 (or equivalently 512).
> I have not asked the program for any resolution so far.
> Any comments gratefully received.
> Ivan


Dimensions come from the physical properties of the image
file. Every file has data in it representing so many pixels high
and so many wide. It is a fixed property of the image unless
you crop, resize or resample it.

"pixels per inch" is an indication from some software in the
camera, scanner, or photo editor to some other software, usually
in a printer driver, telling it how big to print this image. 512
pixels per inch is a very high number. Very high quality prints
are possible at 200-300 ppi. The number is a suggestion.
Your printer software should be able to print the image at
any size you tell it to, regardless of that number - though
in the absence of any other instructions your printer software
might use this suggestion. This number too is stored in the file.

"6.000 x 4.000 inches" is just (3072/512) x (2048/512).
It may not be stored in the file, just computed.

Alan


 
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ivan danicic
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      11-01-2004
Hello, As I said, I know about the dimension of the scanned image, 3072x2048
pixels, but I want to know what theoretical basis there is for the printing
resolution, here 512 ppi. At this stage I would have thought that PSP knows
nothing about what printer will be used, yet there is the suggestion that by
printing at a different resolution something will be lost. Kindly explain.
Ivan.
"Mike Williams" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Wasn't it ivan danicic who wrote:
>>Hello All, I open a picture in psp7 and click on 'image info'.
>>It displays :
>>Image: dimension 3072x2048 pixels.
>> 6.000x4.000 inches.
>> pixels per inch 512.
>>
>>Where does this information come from? I know about the dimension but not
>>about 6x4 (or equivalently 512).
>>I have not asked the program for any resolution so far.

>
> PSP7 always considers an image to have a physical print size as well as
> a dimension in pixels. It's not used very much except when you print the
> image and don't specify anything that overrides it.
>
> When you create a new image, you enter the resolution and can either
> enter the dimension in pixels or the print size in inches or
> centimetres. So if you ask PSP7 to create an image that is 3072x2048
> pixels and has a resolution of 512 pixels/inch then it will calculate
> the print size in inches for you.
>
> Some image file formats store the print resolution, and PSP7 will read
> the value when it opens an existing image.
>
> Some image formats don't have the ability to store the resolution. When
> PSP7 loads such an image it will use the default resolution.
>
> You can change the default resolution under File => Preferences =>
> General Preferences => Rulers and Units.
>
> You can change the print size/resolution of an image without changing
> its dimension with Image => Resize by selecting the "Actual/Print Size"
> button.
>
> --
> Mike Williams
> Gentleman of Leisure



 
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Trev
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      11-01-2004

"ivan danicic" <(E-Mail Removed)> wrote in message
newsRuhd.1681$(E-Mail Removed). ..
> Hello, As I said, I know about the dimension of the scanned image,
> 3072x2048 pixels, but I want to know what theoretical basis there is for
> the printing resolution, here 512 ppi. At this stage I would have thought
> that PSP knows nothing about what printer will be used, yet there is the
> suggestion that by printing at a different resolution something will be
> lost. Kindly explain.
> Ivan.


Divide 3072 pixels by 512 pixels to an inch and you get 6 inch. There is no
change in the image resolution. The printer needs to know how you wish to
pack the pixels together to get a finished size on paper. Of course if you
changed the ppi to 307 you would get a 10 inch wide print


 
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Mike Williams
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      11-01-2004
Wasn't it ivan danicic who wrote:
>Hello, As I said, I know about the dimension of the scanned image, 3072x2048
>pixels, but I want to know what theoretical basis there is for the printing
>resolution, here 512 ppi. At this stage I would have thought that PSP knows
>nothing about what printer will be used, yet there is the suggestion that by
>printing at a different resolution something will be lost. Kindly explain.


If you've scanned the image, then it might make sense for you to use
Image->Resize and use "Actual/Print Size" to set the resolution to that
with which you scanned your image, rather then leaving it at the default
resolution. Then the print size will match the size of your original
source.

It's really up to you what resolution you want PSP to use. PSP7 simply
tells the printer what you told it (or it picked up from the default
that you configured). The PIXELS per inch that PSP tells the printer to
print bears no relationship to the DOTS per inch capability of the
printer. In some cases that loses some of the detail that you scanned,
but then you could say that's because you used too high a resolution
when you scanned it.

--
Mike Williams
Gentleman of Leisure
 
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Alan Meyer
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      11-01-2004
"ivan danicic" <(E-Mail Removed)> wrote in message
newsRuhd.1681$(E-Mail Removed). ..
> Hello, As I said, I know about the dimension of the scanned image,

3072x2048
> pixels, but I want to know what theoretical basis there is for the

printing
> resolution, here 512 ppi. At this stage I would have thought that PSP

knows
> nothing about what printer will be used,


Correct. This is not a command to a specific printer. PSP does not
know what printer you might use. It is a generic suggestion to any printer
to assume that 512 pixels = 1 inch.

> yet there is the suggestion that by
> printing at a different resolution something will be lost. Kindly explain.


What the PSP suggestion is doing is telling the printer that the
author of this image intended to get a 6x4 inch print - in the
absence of any other directives from the guy making the print,
produce a 6x4 inch print for him.

If anything, information will be lost if you print at 6x4 because the
printer
won't be able to actually reproduce 512 pixels per inch and so the driver
will "downsample" the image to its maximum resolution which might
only be 150 ppi, or thereabouts. It will average 3-4 pixels in each
dimension, converting 9-16 (width x height) pixels to a single point
on the page. Understanding dots per inch vs. pixels per inch is also
complicated, but that's another story.

As somebody else pointed out, you may have a setting somewhere
in your PSP configuration defaults that tells it assume everything
will be printed at 6x4 and calculate pixels per inch according, or
to assume everything will be printed at 512 ppi and calculate inches
accordingly. It's probably not something you set, but something
that PSP set for you by default.

You may also see some on screen image viewers respecting this
number - downsampling the image to display it at around 6x4
inches, even though the actual display resolution is only somewhere
between 60 and 100 pixels per inch and pixels must be thrown
away (or averaged away) to get the image that small.

Alan


 
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ivan danicic
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      11-01-2004
Alan Meyer wrote:

> "ivan danicic" <(E-Mail Removed)> wrote in message
> news:h0qhd.27845$(E-Mail Removed) k...
>> Hello All, I open a picture in psp7 and click on 'image info'.
>> It displays :
>> Image: dimension 3072x2048 pixels.
>> 6.000x4.000 inches.
>> pixels per inch 512.
>>
>> Where does this information come from? I know about the dimension but not
>> about 6x4 (or equivalently 512).
>> I have not asked the program for any resolution so far.
>> Any comments gratefully received.
>> Ivan

>
>>

snip
> "6.000 x 4.000 inches" is just (3072/512) x (2048/512).
> It may not be stored in the file, just computed.
>
> Alan

Hello! I have only just installed psp so have had no opportunity to
influence it in any way. OK; I get from all you kind people said that the
512 ppi has no particular significance. If I want best quality rather than
size of print, what should I do, knowing the size of the scanned image and
the possible dots per inch of which my printer (epson 860) is capable?
Thanks in advance.
Ivan.
 
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Jim
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      11-01-2004

"ivan danicic" <(E-Mail Removed)> wrote in message
news:dwwhd.2907$(E-Mail Removed) ...
> Alan Meyer wrote:
>
> Hello! I have only just installed psp so have had no opportunity to
> influence it in any way. OK; I get from all you kind people said that the
> 512 ppi has no particular significance. If I want best quality rather than
> size of print, what should I do, knowing the size of the scanned image and
> the possible dots per inch of which my printer (epson 860) is capable?
> Thanks in advance.
> Ivan.

240 pixels per inch. It is hard to see the difference between 200 and 300
pixels per inch.
1440 dots per inch. I can't see any difference between 1400 and 2880.
Jim


 
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