(pixle per inch) ppi is only 72 HELP

Archived from groups: rec.photo.digital (More info?)

hi i use paint shop pro quite often and have recently noticed the
(pixel per inch) ppi is only 72 on every photo i have taken with my
a80. anyone know why? is it the software reducing ppi?

thanks


Ian

------------
My Photo album
http://public.fotki.com/hurst/
comments welcome

Archived from groups: rec.photo.digital (More info?)

"Ian Hurst (Troyka)" <ywr@spamtrap.com> wrote in message
news:fiaes0htnulondod0d1tq0rrjhkh78njqa@4ax.com...
>
> hi i use paint shop pro quite often and have recently noticed the
> (pixel per inch) ppi is only 72 on every photo i have taken with my
> a80. anyone know why? is it the software reducing ppi?

72 ppi is a computer screen standard (I think it is based on an early
Macintosh). So, if you are sending pictures via email, 72 ppi is about all
one needs. Unfortunately, this default confuses us as some software assumes
it. Mostly, it can be ignored for other purposes such as printing,
archiving, etc.

Archived from groups: rec.photo.digital (More info?)

RE: hi i use paint shop pro quite often and have recently noticed the (pixel
per inch) ppi is only 72 on every photo i have taken with my a80. anyone
know why? is it the software reducing ppi?

------
On the forum at Jasc for Photography and Scrapbook this Resolution topic for
printing often occurs. The following is a response by a Jasc representative
Kris K. The person posting was asking about sizing his image in order to
take it to a printing service to get a 4 * 6 result.

RESOLUTION
If in PSP you do Image > Resize and change the resolution ("Resample Using"
unchecked) the resolution value is changed the normal image data and also
in the EXIF header if present.

If you don't want the number of pixels in the image to change,please 'don't
check' - "Resample Using"- option. When this option is 'not checked' you
change only the' resolution'. As you change the resolution the size of the
image in physical units is modified to reflect the new resolution but the
size in pixels does not change.


When you open an image into PSP for editing it is not in 'any' format. The
image is a device independent bitmap. When you change the image and save it
you choose the format in which you wish it to be saved. If you choose a
lossless compression format such as PSP, TIFF or PNG there will be no JPEG
compression. If you choose the JPEG format the image will be compressed as
if it were being created for the first time. PSP has no way to know if the
image you are saving was, for instance, opened and then filled with
completely new data or opened and changed in a minor way.
Consequently all saving is done as if you were dealing with a newly created
image.

-----------

PaintShoPro.Photography newsgroup is available via server
userforums.jasc.com and digital images are accepted. This forum is available
at the jasc.com site also

Rose

Archived from groups: rec.photo.digital (More info?)

Jim Townsend wrote:

> If you take this file, change it to say 10 inches wide @ 72dpi and make
> sure you *resample*, then it will become a 72dpi x 10inches = 720 pixels
> wide which will fit in most monitors.
>
> It's not the fact that the file is 72dpi that makes it fit, it's the
> fact it was resampled from 3535 to 720 pixels across..

This isn't very helpful info, Jim. He's trying to get his image greater
than 72 ppi, and doesn't know about resizing without resampling.

Gary Eickmeier

Archived from groups: rec.photo.digital (More info?)

> hi i use paint shop pro quite often and have recently noticed the
> (pixel per inch) ppi is only 72 on every photo i have taken with my
> a80. anyone know why? is it the software reducing ppi?

The image from the camera does not have any 'ppi' at all. It is simply
a 2000 x 3000 or whatever pixel count the camera sensor delivers. It is
a dimensionless collection of pixels.

However, when the image is opened in a graphics program, in order to
display the image, the program will use a default ppi. It is the
graphics program which does this, and not a feature of the image
itself. If your graphics program has an image size function, you can
alter the ppi *without* resampling, whereupon the image size changes.
F'rinstance, if your program defaults to 72 ppi, and the image size is
2000 x 3000 pixels, the apparent size on the screen will 2000/72 x
3000/72 inches, that's 27 x 42 inches approx. Which is why you can't
see the whole picture at once. If you tell the program to display the
image at, say, 600 ppi, the image will then be about 3 x 5 inches *on
the screen*. The image itself hasn't been changed at all, only the
pixel display pitch has changed.

The same goes for printing. Specify a size for printing, and the image
delivered to the printer will be at such a ppi as will give the required
size.

NOTE none of the foregoing has resampled the image. If you want to
send a picture over the net, at a given size, say, 5 x 7, at 72 ppi,
then you will have to resample, that is, change the pixel count so that
the image at 72ppi will produce a 5 x 7 image on screen. Now, a 5 x 7
image at 72ppi will be 5*72 * 7*72 pixels, that is, 504 x 360 pixels,
which is an image of 181,440 pixels (far smaller than the 6 million
pixels in the original image. Inevitably, you lose information when you
do this, so don't do it to your original image!!), and a Jpeg file with
about a 10:1 compression will be about 18 kilobytes, a suitable size for
sending over the net.

Hope this helps,

Colin

Archived from groups: rec.photo.digital (More info?)

Gary Eickmeier wrote:

>
>
> Jim Townsend wrote:
>
>> If you take this file, change it to say 10 inches wide @ 72dpi and make
>> sure you *resample*, then it will become a 72dpi x 10inches = 720 pixels
>> wide which will fit in most monitors.
>>
>> It's not the fact that the file is 72dpi that makes it fit, it's the
>> fact it was resampled from 3535 to 720 pixels across..
>
> This isn't very helpful info, Jim. He's trying to get his image greater
> than 72 ppi, and doesn't know about resizing without resampling.
>
> Gary Eickmeier

True.. I got sidelined and took the thread in another direction by
responding to another poster rather than the original poster.

The proper answer to the OP's question is that DPI or PPI of an image is
absolutely meaningless until it comes time to print it. It has nothing
to do with the pixels in the file or the quality of the image.

It's the proposed print size. It's a printing term. The PPI is nothing
more thant the number of pixels in the file divided by the proposed
print size in inches.

The DPI setting exists as 5 bytes at the beginning of the JPEG stream.

2 bytes define the horizontal resolution, 2 bytes define the vertical
resolution and one byte determines whether the resolution is in
dots per inch or dots per centimeter.

These bytes are read by your printing software and determine how
big the image will be when it's printed on paper or whatever you
have in your tray.

You can technically set a file to zero PPI, but most manufacturers plug
in some default value.. Usually 72 or 180. The main problem with having
zero is that the PPI of a file is the number of pixels divided by the proposed
print size in inches.. If you try divide by zero... well.. you just can't.

Archived from groups: rec.photo.digital (More info?)

dylan wrote:
> Where did you get "He's trying to get his image greater than 72 ppi etc"
> from ?

The OP.

Gary Eickmeier