Why pixel peeping (usually) makes no sense

On Nov 17, 8:15 am, John Navas wrote:
On Sat, 17 Nov 2007 09:10:43 +1100, "cmyk" wrote in
With all due respect, that's an essentially meaningless distinction.

(I love it! He says that, and then criticises cmyk for 'insults'.)

So let's just stick to facts.

John, I think you cannot get better than 209 ppi from your Panasonic
at 11 x 14.

If you believe otherwise, perhaps you can show us the math? I'm happy
to be proven wrong.


Best regards,

mt (O:

"John Navas" wrote in message ...
On Sat, 17 Nov 2007 09:10:43 +1100, "cmyk" wrote in
:

"John Navas" wrote in message ...
On Sat, 17 Nov 2007 08:13:14 +1100, "cmyk" wrote in
:

For my 7.2MP Panasonic FZ8, 11x14 is "excellent" at about 216 DPI.

To produce an 11x14 print without interpolation from your FZ8, you can only print at 200ppi. Printing at 216dpi is only going to
degrade the image through interpolation. You can see what's optimum by dividing the print dimensions by the available number of
pixels. That gives an angular resolution of around 115 arc-seconds.

With all due respect, that's an essentially meaningless distinction.

You would do well to take time to study this instead of peremptorily dismissing it.

Been there; done that.

Your response betrays a certain lack of
understanding of some fairly basic issues.

Insults only serve to diminish the credibility of your own argument.

--
Best regards,
John Navas
Panasonic DMC-FZ8 (and several others)

Insults? I'm simply stating -politely - what's patently obvious.

--
cmyk

wrote in message ...
You took most of the words out of my mouth, cmyk - well done..


Thanks

For a:
. 4x6 print, you'd want about 360ppi
. 5x7 print, you'd want 300-360ppi
. 8x10 or 11x14 print, you'd want about 288ppi
. 16x20 print, you'd want about 240ppi
. 20x30 print, you'd want about 200ppi

..these numbers are pretty much what I would accept, too... (O:

By what standard
do you define 'acceptable', 'very good', excellent', 'best'?

Exactly. And then you throw in viewing distance as well? (O: No
wonder it gets argued!


Hi Mark,

For print distances, I'll stick with Kodak's research. AFAIK, no-one else has done any and the old-school notion of viewing distance
= print diagonal or any other similar linear relationship has been thoroughly debunked. And has been for 15 years (Kodak first came
out with this in November 1992).

Cheers
--
cmyk

On Fri, 16 Nov 2007 17:07:49 +0000 (UTC), (David Arnstein)
wrote:

In article ,
John Navas wrote:

This is a nice paper, and you put a lot of work into it. You did not
have much to say about cropping, however.

One of the attractions of digital photography is the ease of post-
processing (compared to using a darkroom!). When I take pictures, my
first priority is to get the shutter button pushed quickly. I can take
care of composition in Photoshop or Thumbs Plus. I admit, I have no idea
how other folks frame their shots. But in my case, higher pixel counts
are useful.

By the way, what is this "print" that you speak of? Is it related to
darkroom techniques and stiff paper? I don't mess with that stuff any
more. Do you?

This is where the skill of the photographer really comes into play. Rarely do I
find any need to crop my photos. Well, some need leveling and then a slight crop
to account for that. The speed of either the manual or electronic zoom in all my
P&S cameras is more than fast enough to frame and shoot in time. I regularly
practice on distant birds in flight at full 400+mm zooms to hone this skill. If
you have the skill and experience you can make do with much fewer pixels to
obtain those high quality large-size prints. I sometimes laugh when someone with
a 20Mpx camera brags about their images after they've had to crop the subject
out of only 1/4th of the frame. Reducing their 20mpx camera to having no better
resolution than a 5Mpx camera. You'd be surprised if you did the math to find
out just how little that you need to crop that higher resolution image to reduce
it to nothing better than a cell-phone camera. If you don't learn how to compose
and frame a shot instantaneously then no amount of money for a camera and
post-processing in the world can compensate for that.

On Fri, 16 Nov 2007 08:49:35 -1000, Scott W wrote:

I also would take some issue with your table of needed pixels, this is a
personal thing. For an 8 x 10 print I would say 4MP is acceptable, but
just and very good would be 8MP. And with a good printer you can see a
noticeable improvement going from 8 to 16 MP for a 8 x 10 print, so I
don't see how even 8MP could be call best for this size print.

It's clear that you never do much photography, nor printing. Even more important
than the number of pixels is the subject matter. With the right subject matter
even the images from 1.2MP cameras (with good optics) can print exceptionally
well at 8x10 sizes.

On Sat, 17 Nov 2007 09:10:43 +1100, "cmyk" wrote:

You would do well to take time to study this instead of peremptorily dismissing it. Your response betrays a certain lack of
understanding of some fairly basic issues.


Your whole post betrays your lack of experience with reality and photography in
general. Print quality is more dependent on subject matter than it will ever do
with PPI settings.

On Nov 17, 2:21 am, ClarkJohnson wrote:
On Sat, 17 Nov 2007 09:10:43 +1100, "cmyk" wrote:
You would do well to take time to study this instead of peremptorily dismissing it. Your response betrays a certain lack of
understanding of some fairly basic issues.

Your whole post betrays your lack of experience with reality and photography in
general. Print quality is more dependent on subject matter than it will ever do
with PPI settings.

It's even more dependent on the photographer having a heartbeat. A
dying photographer generally takes bad pictures as he is preoccupied
with the predicament he finds herself in; for instance, he may well be
engaged in a last-minute reconsideration of his religious beliefs (or
lack thereof), since it's getting urgent, etc. At any rate, it's
unlikely he'll take good pictures.

Anyway, why not mention that too if we won't restrict ourselves to the
number of pixels needed? It's important, no?

"ClarkJohnson" wrote in message ...

Your whole post betrays your lack of experience with reality and photography in
general. Print quality is more dependent on subject matter than it will ever do
with PPI settings.


And just where did I say that subject matter was unimportant, or less important?

But since *you're* claiming "Print quality is more dependent on subject matter than it will ever do with PPI settings", perhaps
you'd care to back that up with some evidence.

--
cmyk

On Sat, 17 Nov 2007 10:54:04 +1100, "cmyk" wrote:

"ClarkJohnson" wrote in message ...

Your whole post betrays your lack of experience with reality and photography in
general. Print quality is more dependent on subject matter than it will ever do
with PPI settings.


And just where did I say that subject matter was unimportant, or less important?

But since *you're* claiming "Print quality is more dependent on subject matter than it will ever do with PPI settings", perhaps
you'd care to back that up with some evidence.

That's easy. Take a picture of a red square with a 1-pixel resolution camera.
You can blow it up to the size of a billboard and it'll still have the same
amount of detail, color, and retain the same shape. The same is true of any
subject depending on what kind of details are in it to begin with.

For all your PPI calculations they'll never hold up in real-world situations.
Sure, those number are fine for the anal couch-potato photographer and
math-brained print-maker who only has web-tv and not even a printer. One who
thinks it's all in the numbers. You know, the digital byte-benders who have
never left their basements, have never touched a real camera, never changed ink
in a printer, nor seen the light of day. But it's not true in the real world.

"ClarkJohnson" wrote in message ...
On Sat, 17 Nov 2007 10:54:04 +1100, "cmyk" wrote:

"ClarkJohnson" wrote in message ...

Your whole post betrays your lack of experience with reality and photography in
general. Print quality is more dependent on subject matter than it will ever do
with PPI settings.


And just where did I say that subject matter was unimportant, or less important?

But since *you're* claiming "Print quality is more dependent on subject matter than it will ever do with PPI settings", perhaps
you'd care to back that up with some evidence.

That's easy. Take a picture of a red square with a 1-pixel resolution camera.
You can blow it up to the size of a billboard and it'll still have the same
amount of detail, color, and retain the same shape. The same is true of any
subject depending on what kind of details are in it to begin with.

That would have to be the lamest 'evidence' possible. It's an insult to your intelligence.

If you take a screen dump of any worthwhile image and print it to a full sized A4/letter page, it'll likely look awful from a normal
viewing distance, even if printed at 1200dpi or more. Doesn't matter how good the image was. Likewise, if you take a 50Mp image then
downsample it to 100dpi for a 6x4 print, all you'll end up with is mush.

The simple fact is that the print resolution is just as important as the subject matter.

If you've got a decent image, then printing it at the optimal print density for the size and viewing distance will give the best
results. Any interpolated image whose density isn't evenly divisible by the printer's maximum resolution is going to suffer. You see
it all the time on-screen when there's a mismatch between the the number of pixels in the image and the number available for
displaying them. Printers suffer from the same limitations, just not so noticeably. Throwing away a few pixels around the margins,
printing to a slightly smaller size to avoid such interpolations, or using a higher resolution that suits the printer (which might
amount to the same thing) is generally preferable.

--
cmyk