> If you compare quality of same size images, printed at the
> same size, there is NO difference,
> whatever their "resolutions" are.
Can't agree there...perhaps we're comparing apples to oranges...
I took a photo on my system that was scanned in at 300 pixels per inch,
1501 pixels wide, and 2098 pixels high. (JPEG)
Took the same photo and resampled it to 72 pixels per inch (ppi),
360 pixels wide, and 503 pixels high. (Maximum quality JPEG setting)
Then, I resampled the 72 ppi image back to 300 ppi, which caused
the print dimensions to swell to about 20 inches wide...
then set the print dimensions to match the original 300 ppi image,
approximately 5x7 inches.
So now we've got two images with the same print dimensions, 5x7...
one with a resolution of 300 ppi and one with a resolution of 72 ppi.
The orginal 300 ppi image looks better onscreen ( you have to look hard to
see
the quality differences), but only slightly because a typical computer
screen
only displays 72 ppi...however in print the 300 ppi image looks a lot
better.
So, it seems from my this experiment, resolution does matter...
With digital cameras, assuming they're taking all photos, regardless of
quality
setting, at the same resolution, then the only difference is print
dimensions,
unless higher resolutions can be set for taking photos and not just larger
image dimensions.
I'm not sure if we're missing something in this discussion,
but I can assure you if a person prints out a 72 pixels per inch image as
opposed to
a 300 pixels per inch image, the 300 pixels per inch image will look better
onscreen and in print.
I think the problem in our discussion has been my use of "dpi" or "dots per
inch", which is printer/scanner term,
as opposed to "ppi" or "pixels per inch" which is an image resolution term.
I should have been using "ppi".
Does using "ppi" as opposed to "dpi" to refer to resolution make
any difference in our discussion?
Rick
> -----Original Message-----
> From: Claude Schneegans [mailto:[EMAIL PROTECTED]
> Sent: Thursday, September 11, 2003 11:22 AM
> To: CF-Talk
> Subject: Re: Image manipulation
>
>
> >>but there is a noticable
> difference in the print quality of an image that is 72dpi that has
> been increased in pixel dimensions to match at print at 300dpi
> with the same pixel dimensions.
>
> Then the images were not the same: the first one was much
> smaller: less pixels in it, so one cannot compare.
>
> If you compare quality of same size images, printed at the
> same size, there is NO difference,
> whatever their "resolutions" are.
> The resolution is the smallest element an instrument can deal with.
> This is meaningfull for measure instruments, copying
> equipment like scanners, or printing equipment.
> As far as data is concerned, like images, resolution has no
> meaning and does not exist.
> What exists for images is the definition. The definition is
> not a ratio like the resolution, but an absolute number.
> An image definition is measured by its number of pixels.
>
> A better example is with TV sets and TV images.
> A TV set has a resolution: the distance between two lines to
> generate the image (vertically). This may be
> variable depending of the size of the screen.
> ALL TV images have the same definition: 525 lines vertically
> (if I remember well), they have NO resolution.
>
> The resolution you find inside a JPG image is not the
> "resolution of the image", it is the resolution
> at which it has been scanned. This has nothing to do with
> the resolution you will print the image.
> Of course, you can set the printer to the same resolution as
> for the scanner, then you will get an image
> of the same size, but who said one has to use the same
> resolution for printing? The printer resolution
> is set by the user, not by the image.
>
> Furthermore, what is the "image resolution" for an image
> coming from a digital camera?
> What does it mean "dots per Inch", since there is NO
> original image?... per inch of WHAT? ;-)
>
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