Digital vs Film Resolution

In the early days of digital photography, it was said that something
equivalent to 35mm file was some time out in the future. Are we there
yet? What digital resolution would be equivalent to 35mm film?

"Dick" LeadWinger wrote in message
...
In the early days of digital photography, it was said that something
equivalent to 35mm file was some time out in the future. Are we there
yet? What digital resolution would be equivalent to 35mm film?

It depends who you ask and how you compare. Film grains can be very small,
but all the grains of film are a specific color (based on their layer in the
film) - shades of color are created by many grains of film clustering
together. In a digital photograph, there are discrete pixels which are
relatively large, but each pixel can take on one of many shades, based on the
amount of light that hits it.

You can test how thin a line each can resolve, but that test is biased toward
film, since you can use a few small grains to represent a line, while a
digital camera might be able to resolve more discrete shades of color in the
same area, but not as fine a detail.

It's kind of like comparing VHS tapes and MPEG compressed video. The nature
of the artifacts you see when you get close and nitpick the image are
different, so you can't really say that one bitrate of MPEG is equivalent to
one recording speed of VHS, because the difference is subjective.

Many people would agree that a 6.x megapixel image with low noise is roughly
equivalent to 400 speed negative film. Both can be blown up to about the same
size before you start to notice flaws without actually looking for them.

Low speed slide film easily beats 6.x megapixel images, I'm not sure if anyone
has compared slide film to the more recent 10+ megapixel cameras.

Ken

"Dick" LeadWinger wrote in message
...
In the early days of digital photography, it was said that something
equivalent to 35mm file was some time out in the future. Are we there
yet? What digital resolution would be equivalent to 35mm film?

If you're just talking resolution, then yes, 6mp sensors or more will give
you about the resolution of film. There's more to it, though. Noise is an
issue and to minimize noise, smaller sensors such as in the point-and-shoots
won't give you as good a result as a dSLR, even at the same resolution
sensor. The other issue is dynamic range. Current dSLRs will generally give
you about as much dynamic range as slide film, maybe about 6 stops. Dynamic
range will improve, as we see in such high-level sensors such as the Creo
Leaf. That $15,000 sensor will give reported 12 stops of dynmamic range,
equal or better than just about any film. So for dynamic range, which is
important, digital is not quite there yet. Give it a couple of years, or
wait and see what kind of DR the Fujifilm S3 dSLR will give us.

HMc

After the techies resolve this argument I submit the quality of your
printer makes it all moot. Not much has been said here in that regard.

Dick wrote:
In the early days of digital photography, it was said that something
equivalent to 35mm file was some time out in the future. Are we there
yet? What digital resolution would be equivalent to 35mm film?

"TRR" wrote in message
hlink.net...
After the techies resolve this argument I submit the quality of your
printer makes it all moot. Not much has been said here in that regard.

Quality is still a moving target. Printers get better so one can reprint as
the technology moves on. But then, digital camera technology will also move
on.

Its not just the quality of the printer that counts. Most film processing
labs today are converting to digital mini labs. If you take your film to
Kmart, Walmar, Target or your local grocery chain, they are processing the
negatives, then scanning them at 400 dpi in their computers. This is even
true for most small photo or camera shops. Costs associated with disposal
of processing chemicals, as well as incentives given to shops to upgrade
equipment is making old fashioned light processing obsolete. The "prints"
you get are made from digital images scanned from your film. Thus, as real
honest to goodness darkrooms disappear, the digital cameras only need to
catch up to the quality of the photo lab scanners.

Bill B

"jjs" wrote in message
...
"TRR" wrote in message
hlink.net...
After the techies resolve this argument I submit the quality of your
printer makes it all moot. Not much has been said here in that regard.

Quality is still a moving target. Printers get better so one can reprint
as the technology moves on. But then, digital camera technology will also
move on.

"TRR" wrote in message
hlink.net...
After the techies resolve this argument I submit the quality of your
printer makes it all moot. Not much has been said here in that
regard.

That just depends on output size. If the image magnification is high
enough, the output medium will outresolve the image.

Bart

"Bart van der Wolf" wrote:
"TRR" wrote:

After the techies resolve this argument I submit the quality of your
printer makes it all moot. Not much has been said here in that
regard.

That just depends on output size. If the image magnification is high
enough, the output medium will outresolve the image.

Exactly. FWIW, current A4 inkjets are _way_ ahead of 6MP digital at A4 (8.25
x 11.5), so if you like detail in your images, there's still room for
improvement in the cameras. (The Epson R800 is very nice.)

In earlier tests at A4 with the Epson 960, I found that my 645 scans provide
more detail than the 960 could render, but that the 960 could render
everything recorded in the 1Ds samples I downloaded. So you need at least
11MP for A4. (If you're as greedy as I.)

(Note that this question ("how _well_ can I print?") is a rather different
question from the usual "how _big_ can I print?". The latter question
invariably turns into a competition over who has the lowest standards almost
immediately.)

David J. Littleboy
Tokyo, Japan

On Thu, 30 Sep 2004 21:23:06 +0900, "David J. Littleboy"
wrote:


"Bart van der Wolf" wrote:
"TRR" wrote:

After the techies resolve this argument I submit the quality of your
printer makes it all moot. Not much has been said here in that
regard.

That just depends on output size. If the image magnification is high
enough, the output medium will outresolve the image.

Exactly. FWIW, current A4 inkjets are _way_ ahead of 6MP digital at A4 (8.25
x 11.5), so if you like detail in your images, there's still room for
improvement in the cameras. (The Epson R800 is very nice.)

In earlier tests at A4 with the Epson 960, I found that my 645 scans provide
more detail than the 960 could render, but that the 960 could render
everything recorded in the 1Ds samples I downloaded. So you need at least
11MP for A4. (If you're as greedy as I.)

(Note that this question ("how _well_ can I print?") is a rather different
question from the usual "how _big_ can I print?". The latter question
invariably turns into a competition over who has the lowest standards almost
immediately.)

I'm curious... (note I havent shot 35mm since I was 8 and I'm 37 now,
lol)

If I took a photo with 35mm film and with say a 300D (6MP) then
produced 3 prints of say the top corner (1/4 size) of the images
with...

1, the original 35mm blown up to say A3
2, the 300D blown up to A3
3, a scan of the 35mm (high res scan) blown up to A3

Which would have the aparent best quality, especially if the software
didnt reduce the output for the digital to a lower DPI and actually
used some upscaleing system (aka Qimage)

Would the original end up showing grain where as the scan and printing
software would actually hide the grain due to its
printing/upscaleing/lancos or some other combination.

Also would the digital with upscaling produce an image equal to one or
both or none of the above. Would the result be subjective as some bits
of the resultant print might look better while others would look worse
compared to the film original enlargment or the digital scan
enlargment.

The reason why I wonder is that, and I know its not how to produce
good quality prints, the current 1 hour (agfa) systems actually have a
very low resolution... and where film is involved they develop the
film, scan the result, then print from the scan at 380dpi for 6/4's
and 260dpi for 8/12's or perhaps peoples idea of perfection has
reduced significently....

It should be noted that the prints dpi is not actually the "on paper"
dpi only the intermediate files processed dpi as the system does some
other things to that file before it scans over the paper... while they
dont specify what they do, i'm guessing its similar to the way Qimage
upscales before sending the data to the actual printer (or in this
case the LED/Lasers)

Enquiring about the apparent "low res" of the agfa I found out that
the max res for all makes of mini labs are 400dpi; none actually
resolve to 600dpi so potentially a home printer exceeds the out put of
the mini labs.

David J. Littleboy
Tokyo, Japan



--
Jonathan Wilson.
www.somethingerotic.com

"Jonathan Wilson" wrote in message
...
SNIP
I'm curious... (note I havent shot 35mm since I was 8 and
I'm 37 now, lol)

If I took a photo with 35mm film and with say a 300D
(6MP) then produced 3 prints of say the top corner
(1/4 size) of the images with...

1, the original 35mm blown up to say A3
2, the 300D blown up to A3
3, a scan of the 35mm (high res scan) blown up to A3

Which would have the aparent best quality, especially if
the software didnt reduce the output for the digital to a
lower DPI and actually used some upscaleing system
(aka Qimage)

Hard to predict because that , amongst others, depends on the skill of
the photographer/operator, and on the definition of quality.
1 doesn't allow much control, except over general colorbalance, 2
depends on the postprocessing an upscaling quality, and 3 depends on
the scanner/operator and postprocessing.

Would the original end up showing grain where as the scan
and printing software would actually hide the grain due to its
printing/upscaleing/lancos or some other combination.

In the case 1, the only way graininess can be controlled is by using a
diffuse lightsource enlarger. It also changes contrast depending on
density (and paper choice combined with processing).
Both cases 2 and 3 allow to reduce noise/graininess by using noise
reduction software, which can be very effective. The upscaling doesn't
help noise, it only increases its size, although there are methods
that simulate edge detail at the expense of fine detail/gradients.

Also would the digital with upscaling produce an image equal
to one or both or none of the above. Would the result be
subjective as some bits of the resultant print might look better
while others would look worse compared to the film original
enlargment or the digital scan enlargment.

Upon close inspection it will be apparent that the DSLR will lack real
resolution by comparison, but has good edge contrast and low noise by
itself (even without noise reduction). From an appropriate distance,
the difference may be hard to notice. It'll require a 1Ds or the Mark
2 version to really meet/exceed the resolution of low ISO film
(assuming quality optics and no camera shake and a stationary
subject).

The reason why I wonder is that, and I know its not how to
produce good quality prints, the current 1 hour (agfa) systems
actually have a very low resolution... and where film is involved
they develop the film, scan the result, then print from the scan
at 380dpi for 6/4's and 260dpi for 8/12's or perhaps peoples
idea of perfection has reduced significently....

Acceptable quality, but then we are lowering standards, varies with
the goal. Perfection is on the other side of the scale and mostly
equipment / skill limited. It is mainly the intended application of
the images that pose the practical limits on the amount of perfection
we need.

It should be noted that the prints dpi is not actually the "on
paper" dpi only the intermediate files processed dpi as the
system does some other things to that file before it scans over
the paper... while they dont specify what they do, i'm guessing
its similar to the way Qimage upscales before sending the data
to the actual printer (or in this case the LED/Lasers)

Probably similar, yes. But different hardware may also allow to
exploit it. For example, although inkjet printers need to dither to
produce intermediary ink colors, where RGB printers don't, they also
allow to produce higher resolution edges (e.g. text).

Enquiring about the apparent "low res" of the agfa I found out that
the max res for all makes of mini labs are 400dpi; none actually
resolve to 600dpi so potentially a home printer exceeds the out put
of
the mini labs.

For edges yes, but it's harder to produce smooth/light gradients. Do
note that 300/400 ppi is close to the visual acuity of the human eye,
but there is a noticable resolution difference with inkjets. But there
are also other issues, like color gamut, which make a 1-on-1
comparison difficult. Cost/output speed is another factor to consider,
besides quality.

Bart