for digital image: enlarge by unsharp or scan at high pixels?

I recently scanned a Polaroid with my Epson V500 scanner set at 2400
pixels. The result was an image that I was able to print with very good
quality as an 8x10. Now if I take an equivalent digital image and try
to enlarge it that much in Photoshop CC, I never get the clarity I just
experienced with this Polaroid enlargement with the scanner. So my
question is that I'm wondering what would happen if I printed out a
small digital image, say something Polaroid size, and then scanned it at
high pixel amount, would I then be able to get a much larger, sharp
clear size once printed?

| So my
| question is that I'm wondering what would happen if I printed out a
| small digital image, say something Polaroid size, and then scanned it at
| high pixel amount, would I then be able to get a much larger, sharp
| clear size once printed?

You can't do any trick to get more pixels.
Enlarging just fills in the gaps with a guess
at what the color would be if you had
higher resolution in the first place. If you
have an image at 100 ppi it's still the same
when printed or re-scanned. The dots will just
get bigger. The additional information for more
dpi simply isn't in the image data. The Polaroid
scan worked because the image wasn't limited
by dpi, so you got whatever resolution the
scanner was capable of.

On 04/17/2015 10:17 AM, Mayayana wrote:
| So my
| question is that I'm wondering what would happen if I printed out a
| small digital image, say something Polaroid size, and then scanned it at
| high pixel amount, would I then be able to get a much larger, sharp
| clear size once printed?

You can't do any trick to get more pixels.
Enlarging just fills in the gaps with a guess
at what the color would be if you had
higher resolution in the first place. If you
have an image at 100 ppi it's still the same
when printed or re-scanned. The dots will just
get bigger. The additional information for more
dpi simply isn't in the image data. The Polaroid
scan worked because the image wasn't limited
by dpi, so you got whatever resolution the
scanner was capable of.

So does this mean non-digital photos can be enlarged much more than
digital equivalents? If so, I'm wondering why the world has been bought
into digital imaging!

| So does this mean non-digital photos can be enlarged much more than
| digital equivalents? If so, I'm wondering why the world has been bought
| into digital imaging!
|
Interesting question. I'm not sure everyone has.
On the other hand, it's a lot easier to remove zits
from Cosmo cover girls, and adjust their hips, with
digital.

On 2015-04-17 14:47:47 +0000, TheSharpener said:

On 04/17/2015 10:17 AM, Mayayana wrote:
| So my
| question is that I'm wondering what would happen if I printed out a
| small digital image, say something Polaroid size, and then scanned it at
| high pixel amount, would I then be able to get a much larger, sharp
| clear size once printed?

You can't do any trick to get more pixels.
Enlarging just fills in the gaps with a guess
at what the color would be if you had
higher resolution in the first place. If you
have an image at 100 ppi it's still the same
when printed or re-scanned. The dots will just
get bigger. The additional information for more
dpi simply isn't in the image data. The Polaroid
scan worked because the image wasn't limited
by dpi, so you got whatever resolution the
scanner was capable of.

So does this mean non-digital photos can be enlarged much more than
digital equivalents? If so, I'm wondering why the world has been
bought into digital imaging!

Not at all. These days digital images for the most part will do much
better than non-digital provided you understand what is going on. Your
scan produced a reasonably good digital reproduction of a non-digital
image. Your small digital image file is obviously a resized (reduced
from original) and highly compressed JPEG which gives you a file wich
has ;ost anywhere from 50%-90% of its original data. When you are
working on that scan you are probably working on a new original TIFF.

There is some information you are not providing us, otherwise you have
an "apples & oranges" situation with your enlargement problem:

What do you call an "equivalent digital image"?
Is it a JPEG, and what size is that file?

What is the origin of the digital image?

You say "equivalent" so I am assuming 2.5"x2.5", or at best 2.5"x3",
probably 72ppi to give you a 180x216 sized image on screen. If that
JPEG is enlarged to 8x10 @ 72ppi you are going to have a 576x720 poor
quality image.

You cannot stretch data which doesn't exist regardless of the method
you use. So your best bet might well be to make a high quality scan and
work with that, but don't expect miracles.
--
Regards,

Savageduck

"Mayayana" wrote in news:mgr790$bku$1@dont-
email.me:

| So does this mean non-digital photos can be enlarged much more than
| digital equivalents? If so, I'm wondering why the world has been bought
| into digital imaging!
|
Interesting question. I'm not sure everyone has.
On the other hand, it's a lot easier to remove zits
from Cosmo cover girls, and adjust their hips, with
digital.



It is difficult to fit a 1000+ exposure roll of film into a half-inch thick
smartphone or to send it through the internet.


---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

TheSharpener wrote:

On 04/17/2015 10:17 AM, Mayayana wrote:

So does this mean non-digital photos can be enlarged much more than
digital equivalents? If so, I'm wondering why the world has been bought
into digital imaging!

A Polaroid photo is created 1:1 from the image formed by the lens, it's
like doing a contact print from a medium format negative, so it is
inherently high resolution. If you were to scan a print made from 35mm neg
etc then you would probably not get the same kind of quality.

People often think prints only have a resolution of about 300 dpi but in
fact they can far exceed that, there's no reason in principle why the
resolution of a print should be less than that of a film negative of the
same size, it's only the fact that prints are usually big enlargements of
small negatives which cripples their resolution, I've had no problem
getting 1200dpi from contact prints.



--
__________________________________________________ _____

If you cannot convince them, confuse them.
-- Harry S Truman
__________________________________________________ _____

In article , TheSharpener
wrote:

| So my
| question is that I'm wondering what would happen if I printed out a
| small digital image, say something Polaroid size, and then scanned it at
| high pixel amount, would I then be able to get a much larger, sharp
| clear size once printed?

You can't do any trick to get more pixels.
Enlarging just fills in the gaps with a guess
at what the color would be if you had
higher resolution in the first place. If you
have an image at 100 ppi it's still the same
when printed or re-scanned. The dots will just
get bigger. The additional information for more
dpi simply isn't in the image data. The Polaroid
scan worked because the image wasn't limited
by dpi, so you got whatever resolution the
scanner was capable of.

So does this mean non-digital photos can be enlarged much more than
digital equivalents?

no. the larger you print anything, the lower the resolution.

If so, I'm wondering why the world has been bought
into digital imaging!

because digital is significantly better.

In article , TheSharpener wrote:

Mayayana:
| So my | question is that I'm wondering what would happen if I
printed out a | small digital image, say something Polaroid size,
and then scanned it at | high pixel amount, would I then be able
to get a much larger, sharp | clear size once printed?

You can't do any trick to get more pixels. Enlarging just fills in
the gaps with a guess at what the color would be if you had higher
resolution in the first place. If you have an image at 100 ppi
it's still the same when printed or re-scanned. The dots will just
get bigger. The additional information for more dpi simply isn't
in the image data. The Polaroid scan worked because the image
wasn't limited by dpi, so you got whatever resolution the scanner
was capable of.

So does this mean non-digital photos can be enlarged much more than
digital equivalents? If so, I'm wondering why the world has been
bought into digital imaging!

The "sharpness" of an image is a result of its resolution, which is true for both
analog and digital. If you have a small digital file, it can't be printed at 8x10
in a satisfactory manner. This is true for analog originals as well.

Difference is, many modern digital cameras have sensors that far surpass the
granularity of analog film.

A analog film frame is 36x24mm, and some films were (are?) rated at 200 lines/mm
but most less than that. Unless you were using high-end film, your film has lower
resolution than that. Now, on top of that, there is grain to account for, so I
would say that 50 lines/mm is "good" and 100 lines/mm is really good. This is at
the optimum f-stop and a camera on a tripod.

Let's settle at 75 lines/mm. Each "line" is a complete light and dark cycle, so
each line is equivalent to at least two pixels on a digital sensor, so 75
lines/mm translates to 150 pixels per mm - and some basic math says that an
equivalent digital sensor should thus have 150 * 36 vertical pixels and 150 * 24
horizontal pixels, i.e. 5400 x 3600 which is 19.4 megapixels.

But, just as analog film has grain does digital film have noise, and aliasing and
other artifacts that stem from the digital sensor. But I think it's safe to say
that with modern cameras, the resolution of the digital sensor surpasses the
analog film greatly.

On top of that, modern digital sensors also get a lot more dynamic range than
analog film, which means you have more information in that digital file than in
an analog negative.

If you have a low-resolution digital file that you want to print large, I suggest
looking at Alien Skin's "Blow Up":

http://www.alienskin.com/blowup/

It's a Photoshop/Lightroom plugin (and stand-alone, I think) application that
does digital enlargements better than Photoshop's built in resampling functions.
It's not perfect, but it's pretty good.

--
Sandman