a high res question

Thank you very much Chuck. I just don't know enough about this stuff. That's why I come here...I knew you'd answer ;) I'm not complaining about the high res 8 X 10's I get though ....yay ! I'll go ahead and lower it to 360 and see what i get. So, generally, resampling this way isn't such a bad thing ? I never thought I'd have to consider taking pixels away for printing !

Jodi,

My camera makes picture of 3072 x 2048. So, at 6 x 4, it makes 512 pixels per inch. I've never had
to resample or downsize the number of pixels to get them to print. I have an HP 940Cvr and it
discards the extra information is doesn't need. It may takes a few extra seconds to send the
information to the printer, this I can't really tell. It doesn't take more ink because its ink
consumption has been consistent since I got it, and at that time, I had a 2.2 Mp camera (compared to
a 6Mp now).

Ray

Ray, like you, I'm becoming a believer in the view that printers don't
'waste ink' when you send them more pixels than they need. However, I'm
trying to dredge up a reference that I read once which indicated that excess
image resolution could actually cause a degradation in the printed image.
That may have been more myth than fact, but I'm still going to look for it
just to satisfy my curiosity.

Chuck

"JodiFrye" <lwsfrye@mybizz.net> wrote in message
news:2ccd80ee.-1@webx.la2eafNXanI...

> ok, I am not used to the higher resolution of my new camera. With
> my other Kodak point and shoot it gave me 300 res for a 4 X 6
> picture which seemed great for printing my multiple image album
> pages . With the new camera for an approx 4 X 6 it gives me 470
> resolution. I'm almost scared to send it to the printer.

I'm not sure what you're asking. 4x6 should print as 4x6 (assuming no
changes to the print settings), no matter what the image resolution is given
as. The only difference is how much detail there is, and whether the
printer is capable of showing all of that detail at that size.

Don't be scared to send it to the printer. Embrace all those extra
pixels...they are good for you. :)

Pete

"Chuck Snyder" <csnyder@houston.rr.com> wrote in message
news:6332FB78BDC6EE6BC5CB756208E4372A@in.webx.la2e afNXanI...

> Ray, like you, I'm becoming a believer in the view that printers don't
> 'waste ink' when you send them more pixels than they need. However, I'm
> trying to dredge up a reference that I read once which indicated that

excess

> image resolution could actually cause a degradation in the printed image.
> That may have been more myth than fact, but I'm still going to look for it
> just to satisfy my curiosity.

It just depends. It may have even been a rampant problem in the early days
of color printers (though there was no such problem with my ImageWriter II).
But I believe that these days, the printer driver has been designed
carefully to take the best advantage of the printer hardware, a luxury that
Adobe doesn't have (since they have to work on all hardware).

To print an image created with a different resolution than being used to
print it, *some* component somewhere will have to resample the image. IMHO,
it is much better to let the printer driver do the resampling, than to do it
in advance with a piece of software that doesn't know the fine details of
the printer's performance characteristics.

Same thing with respect to adjusting the image resolution to be an even
fraction of the printer's resolution. At the point that the image is
captured, if you have the option of doing this, that's a good idea. But
once you have the digital image in the computer, you should let the printer
driver do as much of the resampling as possible, even if that means feeding
it an image with a resolution that's not an even fraction of the printer's
resolution.

Finally, as far as the "extra ink" thing goes, I still have no idea where
that came from, and I can say with great confidence that the printer will
use the same amount of ink regardless of the resolution of the original
image. The *print* resolution may well affect ink consumption (just feel
how much "wetter" a piece of paper feels after being printed at 2880 dpi vs
720 dpi, for example), but the original data being sent to the printer will
not affect ink consumption in any way.

Pete

Pete, I was more concerned with the printer than anything else. I was afraid to throw too much at it considering it had never printed above 300 res since i bought it ( I never gave it more than that ) and I get awesome prints out of it. I don't want to mess up my relationship with it...I guess I'm a freak about my equipment. Chuck, I'll be waiting to see what info you come up with...if it tosses out what it doesn't need then fine, I have nothing to be concerned about.

Pete, one thing still has me baffled on image resolution vs. printer
resolution: the difference between a pixel and a printer 'dot'. Image
resolution is easy - it's the number of pixels per inch, with each pixel
being a square consisting one of 16.7 million colors. On the other hand, a
printer has to use multiple 'dots' of cyan, magenta, yellow, and black ink
to form its equivalent of a pixel - some references say as many as 50 dots
in a matrix to comprise a pixel. My understanding is that the dots are put
in close proximity to each other so that the eye sees them as a single
color - but they're still discrete dots. The $64 question is: is the dpi
of a printer counting the individual dots of color in an inch of print, or
is it somehow a 'pixel equivalent' number where the actual number of dots
per inch is much larger? If it's the former, the relationship between image
ppi and printer dpi isn't one-to-one; if it's the latter, then a 1:1
correspondence is possible. It would be great if it was a pixel equivalent:
then one could 'tune' the images in Elements to feed the printer its desired
resolution. I'm sure the better printers have good interpolation
algorithms; not so sure about the ones that come free with a computer....
:-)

Chuck

"Chuck Snyder" <csnyder@houston.rr.com> wrote in message
news:93209C738567B32F80389E5C78245B8E@in.webx.la2e afNXanI...

> [...] The $64 question is: is the dpi
> of a printer counting the individual dots of color in an inch of print, or
> is it somehow a 'pixel equivalent' number where the actual number of dots
> per inch is much larger?

Printer resolution is reported in the maximum number of dots printable, and
does not take into account the dithering required to print 24-bit color on
what is effectively a 4- to 8-bit device (depending on how many colors of
ink the printer uses).

*However*, just because you lose effective resolution due to the dithering
(just as you would when using a halftone screen in a conventional printing
process), that doesn't mean that providing the printer with as high a
resolution image as possible isn't useful. There are actually a variety of
dithering techniques in use (one common one being "error diffusion"), but
all of them can benefit from additional image data.

The reason comes down again to the question of where the resampling is done.
The printer driver, being intimately familiar with the hardware, can do THE
most effective job of resampling in order to produce an image that most
closely matches the original digital data. It knows the exact shades of
each of the inks being used, and it knows how it to blend those shades just
so to match the original image. It can also adjust the dithering so as to
preserve apparent lines in the image, helping to reduce the appearance of
aliasing in the printed image.

Let's take an extreme example and look at it. Consider a 300 dpi B&W laser
printer using half-toning (which is essentially just another kind of
dithering). Let's say you choose a half-tone screen that drops the
effective resolution down to about 50 dpi (I guess we want a lot of
gray-scale resolution :) ). Now, print an image that has a single diagonal
line on it, first at 300 dpi, and then at 50 dpi.

You *will* be able to see a noticeable difference between the two printouts.
While the effective resolution for both is still just 50 dpi, you will find
that the image printed at 300 dpi still has less "jaggies" than the one
printed at 50 dpi. Yes, the "grain" of the half-tone screen will make the
edge of the line a little fuzzier, but you'll get more of an anti-aliased
effect rather than a hard edge at the edge of the line.

Another way to think about it is to realize that there's "real" resolution
and "effective" resolution. "Real" resolution is how many dots that can be
reproduced, and "effective" is how much detail can actually be reproduced.
What "effective" is describing is, what is the smallest "feature" that you
would be able to resolve at that resolution? Sort of like the resolution of
spy satellites, when they say they can resolve down to 10 meters or 1 meter
or whatever. But with a spy satellite, just because you can only resolve
down to 10 meters, that doesn't mean that a car only 5 meters long won't
show up. It just means that you won't be able to tell exactly that it's a
car.

Same thing with printed output. At the "effective" resolution, you'll find
the limits of being able to identify a feature in the image clearly. But
that doesn't mean that there won't be any additional detail smaller than
that. It just means it will be harder to tell what that additional detail
is.

Finally, as far as "the ones that come free with a computer", I think you'll
find that, other than the maximum resolution the printer is capable of (the
"free" ones are usually down in the 720dpi range, while the expensive ones
are up in the 2880dpi range), they are using substantially the same software
to run the printer, and thus would take the same advantage in the dithering
algorithms that the more expensive printers do.

In fact, the drivers that came with my Epson 2200 appear to be used for all
(or almost all) of the current Epson line, and likewise the HP drivers I
downloaded a few weeks ago just to play with also appear to cover an entire
HP product line (their "photo" printers).

So I would still send as high a resolution image as possible to the less
expensive printers. Obviously you'll reach a point of diminishing returns.
The driver can only do so much, and can't create resolution in the printer
where none exists. I doubt sending a 2880 dpi image to a 720 dpi printer is
going to be much better than sending a 720 or 1440 dpi image, if at all.
But up to and including the actual resolution of the printer, more dots are
better.

If all one is trying to do is print a picture at a particular size on the
printer, I do not think it is EVER useful to resample the picture in
Elements or a similar editing program. All such programs allow you to
specify the final printed size without changing the underlying pixel data,
and that's the right way to print a specific size.

All IMHO, of course.

Pete