Yes, it was the resampling that I wasn't accounting for...and
the fact that I was working with a JPEG, which is lossy...
But I've learned something today about the resampling issue.
Claude and I were both right from our perspective, we just didn't realize I
was resampling
the photo. Thanks for helping with the clarification...
Rick
> -----Original Message-----
> From: Kevin Graeme [mailto:[EMAIL PROTECTED]
> Sent: Thursday, September 11, 2003 12:56 PM
> To: CF-Talk
> Subject: Re: Image manipulation
>
>
> Trust me, you really don't want to get into the differences
> between Pixels
> Per Inch, Dots Per Inch, and Lines Per Inch. (LPI is important for
> professional press printing.) I'd have to write pages and
> pages and bust out
> the diagrams and graphics for explanation. You also _really_
> don't want to
> get into a discussion of screen resolution and 72ppi. That's
> even more
> messy. (I used to teach Photoshop and that was the part
> where the students
> would nod off.)
>
> I'll put money down that you'll find absolutely no
> difference when printing
> the 300 ppi image and the unresampled 72 ppi image, provided
> you save them
> in a lossless format. That's because the images really are
> exactly the same.
> You're only modifying metadata about what size to print the image.
>
> -Kevin
>
> ----- Original Message -----
> From: "Rick Faircloth" <[EMAIL PROTECTED]>
> To: "CF-Talk" <[EMAIL PROTECTED]>
> Sent: Thursday, September 11, 2003 11:28 AM
> Subject: RE: Image manipulation
>
>
> > I think you're right, Kevin...
> >
> > I've been inappropriately using "dpi" instead of "ppi",
> "pixels per inch",
> > when discussing image resolution.
> >
> > Also, I did have "Resample Image" checked. (Adobe
> Photoshop Elements 2.0)
> > I'll have to make more use of checking, unchecking that box...
> >
> > And yes, I was actually creating a new "resampled" file
> for comparison,
> > both onscreen and in print.
> >
> > The JPEG compression (even on highest setting) and resampling were
> > probably accounting for the difference in quality...I'll
> have to run a
> > screen and print test
> > on the original 300 ppi image and its "un-resampled" 72
> ppi twin to see
> > what the differences to turn out to be.
> >
> > Thanks for clarifying...
> >
> > Rick
> >
> >
> > > -----Original Message-----
> > > From: Kevin Graeme [mailto:[EMAIL PROTECTED]
> > > Sent: Thursday, September 11, 2003 11:57 AM
> > > To: CF-Talk
> > > Subject: Re: Image manipulation
> > >
> > >
> > > Are you using something like Photoshop or Fireworks? In the
> > > Image Size box,
> > > there is a checkbox called "Resample Image". You probably
> > > have that (or
> > > something equivalent) checked and it's physically reducing
> > > the number of
> > > pixels in the image. That's why you're seeing that effect.
> > >
> > > When you do that, you're not _really_ changing the dpi,
> > > you're changing the
> > > total number of pixels. You're actually creating a different
> > > image, not the
> > > same image at a different dpi resolution. The software just
> > > provides the
> > > ability to edit the dpi as a shortcut to calculating the
> > > resize ratio. If
> > > you uncheck that box and change from 300 to 72,
> you're now actually
> > > preserving the image AND changing the effective dpi.
> > >
> > > The only accurate measure of an image's true size is the
> > > number of pixels in
> > > the image. Resolution (dpi/ppi) is just a measure of how
> > > many of those
> > > pixels are in a given size. If you preserve the
> number of pixels,
> the
> > > resolution will increase as you shrink the display/print
> > > size because it's
> > > the same number of pixels in a tighter space. Inversly, the
> > > resolution will
> > > decrease as you expand the display/print size.
> > >
> > > Understanding this relationship is integral to manipulating
> > > graphics between
> > > screen and print, but a lot of people don't really get into
> > > it because the
> > > tools generally do a good job of hiding it. But the image
> > > manipulation tags
> > > are probably going to expose it, and it's the format you'll
> > > need to work
> > > with.
> > >
> > > -Kevin
> > >
> > > ----- Original Message -----
> > > From: "Rick Faircloth" <[EMAIL PROTECTED]>
> > > To: "CF-Talk" <[EMAIL PROTECTED]>
> > > Sent: Thursday, September 11, 2003 9:42 AM
> > > Subject: RE: Image manipulation
> > >
> > >
> > > > Hi, Kevin...and thanks for the reply and help...
> > > >
> > > > I'm not quite sure how this works out:
> > > >
> > > > >A 800x600 image at 72 dpi is exactly the same
> > > > >as a 800x600 image at 300 dpi.
> > > > >They both weigh in at 1.4MB
> > > >
> > > > I took a 1051 x 2098 image and at 300 dpi it's 3,067KB.
> > > > At 72 dpi, it's 360 x 503 and 220KB...
> > > >
> > > > That's quite a difference when the file is
> uploaded and displayed
> > > > on screen. They both can be made to fit a 320 wide area
> onscreen,
> > > > but the 72 dpi resolution image is obviously more
> desirable
> because
> > > > of reduced file size that's loading onto the page.
> > >
> > >
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