Printer Resolution Versus Image File Resolution

Printer Resolution Versus Image File Resolution

Post by Meato » Mon, 03 Jan 2000 04:00:00



Hi All,

I have a question regarding printer resolution versus original JPG file
resolution. I have skimmed several times through Deke McClelland's Photoshop
Bible for 5.0 and have not found a clear cut satisfying answer. I hope some of
you  knowledgeable readers can set me straight.

I am confused about this resolution thing. Please correct me if I am wrong; I
have always assumed that I can't get more true resolution from an image file
once it is out of the camera.

Do I have to convert the resolution of my JPG file to 266 pixels per inch or
just print it as it exists and let my printer software do the conversion (will
it do the conversion)?

Converting a 4.5Mbyte file to a resolution of  266 pixels per inch causes me to
use up approximately 4 times the amount of disk storage. Is this step really
necessary?

Just for the record, I use a DC260 Kodak Digital Camera to produces JPG images
1536 pixels wide by 1024 pixels high at 72 pixels per inch resolution (per
Photoshop 5.5  menu item Image->Image Size).  I like to make 8"x10" prints from
my JPG images using EPSON Photo Paper S041141. My software settings on my EPSON
Stylus printer are set to: (1) Media Type is set to Photo paper, (2) Ink is set
to color, (3) Mode is set to automatic, the quality/speed slider is set to
quality (I believe the quality slide setting is equivalent to 360dpi)

All responses to my questions are much appreciated.

Many Thanks,

Bruce L.

 
 
 

Printer Resolution Versus Image File Resolution

Post by Ross » Mon, 03 Jan 2000 04:00:00


The number of pixels you get from your camera is the limiting factor
for the resolution you can produce with those pixels. You can squeeze
those pixels into however many inches you like. The more you squeeze
per inch, the higher the resolution, and smaller the size.

A 1536 x 1024 pixel image displayed or printed at 72 ppi/dpi will be
about 21 x 14 inches in size. Obviously, most computer screens, at
this resolution, are not large enough to display the whole image at
100% zoom. It's too large for most printing, as well.

If your monitor is large enough, and can display 100 pixels per inch,
then at 100% zoom the same image will be about 15 x 10 inches. You'd
need to be running your video card/monitor at 1600 x 1200.

If you print the image at 266 dpi, the result will be about 5.75 x
3.85 inches.

8 x10 isn't the right aspect ratio for your image, which is 3 x 2. If
you want a print that is 8 inches wide, you need to print at 192 dpi,
and your height will be about 5.3". You could center the image on an 8
x 10 canvas, or crop the width to get the right aspect. You could also
print landscape, in which case you'd print at about 150 dpi.

Keep in mind, that when you print color or grayscale graphics, printer
dots do not equal pixels. A 200 ppi image is a pretty decent
resolution for printing to an inkjet printer.

For printing, you change the dpi setting for an image with the Image
-> Image Size... command. If you turn resampling OFF, you won't change
the number of pixels in your image, only the size it will be printed
at. OTOH, If you RESAMPLE the image to another resolution (dpi), you
will either add or subtract pixels to/from the image. PS will use
interpolation to decide how to eliminate or create pixels. Resampling
down is not too destructive if you need to do it, but resampling up
isn't normally recommended. You can't increase the "true" resolution
of an image by resampling up. You just make the existing pixels larger
and blurrier, and increase file size.

Hope that helps.
Ross


Quote:>Hi All,

>I have a question regarding printer resolution versus original JPG file
>resolution. I have skimmed several times through Deke McClelland's Photoshop
>Bible for 5.0 and have not found a clear cut satisfying answer. I hope some of
>you  knowledgeable readers can set me straight.

>I am confused about this resolution thing. Please correct me if I am wrong; I
>have always assumed that I can't get more true resolution from an image file
>once it is out of the camera.

>Do I have to convert the resolution of my JPG file to 266 pixels per inch or
>just print it as it exists and let my printer software do the conversion (will
>it do the conversion)?

>Converting a 4.5Mbyte file to a resolution of  266 pixels per inch causes me to
>use up approximately 4 times the amount of disk storage. Is this step really
>necessary?

>Just for the record, I use a DC260 Kodak Digital Camera to produces JPG images
>1536 pixels wide by 1024 pixels high at 72 pixels per inch resolution (per
>Photoshop 5.5  menu item Image->Image Size).  I like to make 8"x10" prints from
>my JPG images using EPSON Photo Paper S041141. My software settings on my EPSON
>Stylus printer are set to: (1) Media Type is set to Photo paper, (2) Ink is set
>to color, (3) Mode is set to automatic, the quality/speed slider is set to
>quality (I believe the quality slide setting is equivalent to 360dpi)

>All responses to my questions are much appreciated.

>Many Thanks,

>Bruce L.


 
 
 

Printer Resolution Versus Image File Resolution

Post by BHilton6 » Mon, 03 Jan 2000 04:00:00



>I am confused about this resolution thing. Please correct me if I am wrong; I
>have always assumed that I can't get more true resolution from an image file
>once it is out of the camera.

You can resample up to a bigger image but at a loss in quality.  Based on the
rest of your post I think this is what you are accidentally doing now.  

Quote:>Do I have to convert the resolution of my JPG file to 266 pixels per inch or
>just print it as it exists and let my printer software do the conversion
>(will it do the conversion)?

You have to change the resolution.  Use Image > Image Size and turn off
'resample image' check box.  This lets you keep the same number of pixels but
basically arrange them differently for different image print sizes.  Then enter
either the desired width or length and Photoshop calculates the dpi, or enter
dpi and see what width/length you will get.

Quote:>Converting a 4.5Mbyte file to a resolution of  266 pixels per inch causes me
>to
>use up approximately 4 times the amount of disk storage. Is this step really
>necessary?

This is what happens if you leave the 'resample image' box checked, Photoshop
is resampling your file to a much greater size.  You don't want this ...
uncheck 'resample image'.

Quote:>Just for the record, I use a DC260 Kodak Digital Camera to produces JPG
>images
>1536 pixels wide by 1024 pixels high at 72 pixels per inch resolution (per
>Photoshop 5.5  menu item Image->Image Size).  I like to make 8"x10" prints
>from
>my JPG images using EPSON Photo Paper S041141. My software settings on my
>EPSON
>Stylus printer are set to: (1) Media Type is set to Photo paper, (2) Ink is
>set
>to color, (3) Mode is set to automatic, the quality/speed slider is set to
>quality (I believe the quality slide setting is equivalent to 360dpi)

I think Epson Photo Paper prints best when the printer setting is for 1440 dpi
(I have a different Epson, the EX, and this is what works best on it ... your
mileage may vary with a different printer).  This 1440 dpi is not the same as
the file resolution.  Most people report the best input file resolution is 240
- 360 ppi for the Epson's at 1440 dpi.  

To get an 8x10-ish print from your 1536 x 1024 pixels you could print at 154
dpi (10 inches x 154 dpi => 1,540 pixels) and get an image 10 x 6.6" or so.
Note that you need a lot more pixels than this to print at 240 dpi ... ie, 8 x
10" would require 1920 x 2400 pixels.  Which is why people get better large
prints from 35 mm film + scanners as compared to the sub-$1000 digi-cams.

Quote:>All responses to my questions are much appreciated.

Hope this helps a bit.
 
 
 

Printer Resolution Versus Image File Resolution

Post by David Ye » Tue, 04 Jan 2000 04:00:00



> I think Epson Photo Paper prints best when the printer setting is for 1440 dpi
> (I have a different Epson, the EX, and this is what works best on it ... your
> mileage may vary with a different printer).  This 1440 dpi is not the same as
> the file resolution.  Most people report the best input file resolution is 240
> - 360 ppi for the Epson's at 1440 dpi.  

Just to clear this up, can you explain briefly what the dpi on the printer
refers to and how it corresponds to, if at all, the image ppi?  Will a
higher printer dpi always result in a better printout, or is it limited by
the resolution of the image, such that printing at a high dpi becomes a
"waste" for some images?

Thanks,
dave

 
 
 

1. newbie question-file resolution vs. printer resolution

Hi,
I have a basic question about the relationship between the printer
resolution and the file resolution.
For example-I am printing a photo from Photoshop to a printer that can print
1200 x 1200 dpi.  I have read that the standard for print is 300 dpi.  When
printing from PS it seems the highest res. I can set it at is 600 dpi (in
the print...menu).  Can someone please explain to me how one gets the
maximum photo quality from a printer that can do 1200 x 1200?
I hope my question makes sense, and that someone can explain this to me.
Thank you,
Michelle

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