contrast in p&s digital cameras vs film

Hello,

I was wondering if anybody can comment on the quality of contrast in the
pictures taken with a point and shoot digital camera compared to the one
obtained on 35mm film.

I have seen pictures from Canon A520 and a few older models. I can
usually pick them out from the ones scanned from negatives quite easily.
The ones taken with digital cameras usually appear to have less contrast
and less amount of colors (less saturated colors?).

Anybody know of any recent digital cameras in which the colors are
better and we can have more contrast? I know this may appear to be a bit
vague, but related comments are welcome.

thanks,
-HS

H.S. wrote:
Hello,

I was wondering if anybody can comment on the quality of contrast in the
pictures taken with a point and shoot digital camera compared to the one
obtained on 35mm film.

I have seen pictures from Canon A520 and a few older models. I can
usually pick them out from the ones scanned from negatives quite easily.
The ones taken with digital cameras usually appear to have less contrast
and less amount of colors (less saturated colors?).

Anybody know of any recent digital cameras in which the colors are
better and we can have more contrast? I know this may appear to be a bit
vague, but related comments are welcome.

The main reason is that film has a toe in its characteristic
curve and digital cameras are linear. They are also linear
at the low end after the "gamma" tone curve is applied.
Learn to use curves to add an s-curve response to give a
film-like response. You can boost contrast in camera, but
post processing gives more control over shadow and highlight detail.

Roger

On Oct 14, 9:05 am, "Roger N. Clark (change username to rnclark)"
wrote:
H.S. wrote:
Hello,

I was wondering if anybody can comment on the quality of contrast in the
pictures taken with a point and shoot digital camera compared to the one
obtained on 35mm film.

I have seen pictures from Canon A520 and a few older models. I can
usually pick them out from the ones scanned from negatives quite easily.
The ones taken with digital cameras usually appear to have less contrast
and less amount of colors (less saturated colors?).

Anybody know of any recent digital cameras in which the colors are
better and we can have more contrast? I know this may appear to be a bit
vague, but related comments are welcome.

The main reason is that film has a toe in its characteristic
curve and digital cameras are linear.

Is that so? My reading of the Gurney-Mott business (a couple of years
ago and very superficial) led me to conclude that the formation of the
latent image on film is also a linear process (as long as you're not
in the region of low or high intensity reciprocity failure). The
characteristic curve comes when you develop it. So I don't see how
this is any different from digital capture, where the detection is
linear and you then apply a curve. I'm not an expert and just scanned
the paper quickly, so may have completely misunderstood it.

I'd say the difference the OP see is because of the processing, which
I think deserves a lot more attention than people seem to think. I
know this is also what you say below, but I think saying that one is
linear and the other isn't is not accurate (as it refers to different
stages of capture/development in each case). But maybe I am wrong.


They are also linear
at the low end after the "gamma" tone curve is applied.
Learn to use curves to add an s-curve response to give a
film-like response. You can boost contrast in camera, but
post processing gives more control over shadow and highlight detail.

acl wrote:
On Oct 14, 9:05 am, "Roger N. Clark (change username to rnclark)"
wrote:
H.S. wrote:
Hello,
I was wondering if anybody can comment on the quality of contrast in the
pictures taken with a point and shoot digital camera compared to the one
obtained on 35mm film.
I have seen pictures from Canon A520 and a few older models. I can
usually pick them out from the ones scanned from negatives quite easily.
The ones taken with digital cameras usually appear to have less contrast
and less amount of colors (less saturated colors?).
Anybody know of any recent digital cameras in which the colors are
better and we can have more contrast? I know this may appear to be a bit
vague, but related comments are welcome.
The main reason is that film has a toe in its characteristic
curve and digital cameras are linear.

Is that so? My reading of the Gurney-Mott business (a couple of years
ago and very superficial) led me to conclude that the formation of the
latent image on film is also a linear process (as long as you're not
in the region of low or high intensity reciprocity failure). The
characteristic curve comes when you develop it. So I don't see how
this is any different from digital capture, where the detection is
linear and you then apply a curve. I'm not an expert and just scanned
the paper quickly, so may have completely misunderstood it.

I'd say the difference the OP see is because of the processing, which
I think deserves a lot more attention than people seem to think. I
know this is also what you say below, but I think saying that one is
linear and the other isn't is not accurate (as it refers to different
stages of capture/development in each case). But maybe I am wrong.

Film has a portion of the characteristic curve that
is linear on a log-log plot. The slope varies with
developing and type of film. Slope can be close to 1 in
some film+developer combinations. But that does not change the
fact that film has a toe. This is illustrated in Figure 8b at:
http://www.clarkvision.com/imagedetail/dynamicrange2

On a print, some point on the toe is set to black, and that
is the main effect giving nice blacks. Try it in a photo
editor on a digital camera image: use the curves tool,
and somewhere near the low end, pull the curve down.
Contrast goes up (also try boosting the highs).
This is the same effect as printing and exposing the print
to give nice black somewhere above zero response.
You can do this with levels tool too, but the transition
is not smooth; I prefer curves.

Roger



They are also linear
at the low end after the "gamma" tone curve is applied.
Learn to use curves to add an s-curve response to give a
film-like response. You can boost contrast in camera, but
post processing gives more control over shadow and highlight detail.

On Oct 14, 6:23 pm, "Roger N. Clark (change username to rnclark)"
wrote:
acl wrote:
On Oct 14, 9:05 am, "Roger N. Clark (change username to rnclark)"
wrote:
H.S. wrote:
Hello,
I was wondering if anybody can comment on the quality of contrast in the
pictures taken with a point and shoot digital camera compared to the one
obtained on 35mm film.
I have seen pictures from Canon A520 and a few older models. I can
usually pick them out from the ones scanned from negatives quite easily.
The ones taken with digital cameras usually appear to have less contrast
and less amount of colors (less saturated colors?).
Anybody know of any recent digital cameras in which the colors are
better and we can have more contrast? I know this may appear to be a bit
vague, but related comments are welcome.
The main reason is that film has a toe in its characteristic
curve and digital cameras are linear.

Is that so? My reading of the Gurney-Mott business (a couple of years
ago and very superficial) led me to conclude that the formation of the
latent image on film is also a linear process (as long as you're not
in the region of low or high intensity reciprocity failure). The
characteristic curve comes when you develop it. So I don't see how
this is any different from digital capture, where the detection is
linear and you then apply a curve. I'm not an expert and just scanned
the paper quickly, so may have completely misunderstood it.

I'd say the difference the OP see is because of the processing, which
I think deserves a lot more attention than people seem to think. I
know this is also what you say below, but I think saying that one is
linear and the other isn't is not accurate (as it refers to different
stages of capture/development in each case). But maybe I am wrong.

Film has a portion of the characteristic curve that
is linear on a log-log plot. The slope varies with
developing and type of film. Slope can be close to 1 in
some film+developer combinations. But that does not change the
fact that film has a toe.

I realise that. What I am trying to say is this: When one says that
digital capture is linear, one is referring to the raw data. The
equivalent object in film capture isn't a developed slide or negative,
but the latent image (before development). And, as far as I remember,
the effect there is also linearly related to the light
intensity*exposure time; it is after development that you get a
nonlinear response, just like after raw conversion you get a nonlinear
response (if you've applied a curve).

I say that because I keep seeing statement like "digital is linear and
film isn't" as explanations of all sorts of things, and this puzzles
me because in one case we are discussing fully developed negatives/
slides while in the other completely undeveloped data.

But, as I said, maybe I am wrong and the latent response isn't linear.

This is illustrated in Figure 8b at:http://www.clarkvision.com/imagedetail/dynamicrange2

On a print, some point on the toe is set to black, and that
is the main effect giving nice blacks. Try it in a photo
editor on a digital camera image: use the curves tool,
and somewhere near the low end, pull the curve down.
Contrast goes up (also try boosting the highs).
This is the same effect as printing and exposing the print
to give nice black somewhere above zero response.
You can do this with levels tool too, but the transition
is not smooth; I prefer curves.

Roger



They are also linear
at the low end after the "gamma" tone curve is applied.
Learn to use curves to add an s-curve response to give a
film-like response. You can boost contrast in camera, but
post processing gives more control over shadow and highlight detail.

acl wrote:

I realise that. What I am trying to say is this: When one says that
digital capture is linear, one is referring to the raw data. The
equivalent object in film capture isn't a developed slide or negative,
but the latent image (before development). And, as far as I remember,
the effect there is also linearly related to the light
intensity*exposure time; it is after development that you get a
nonlinear response, just like after raw conversion you get a nonlinear
response (if you've applied a curve).

I say that because I keep seeing statement like "digital is linear and
film isn't" as explanations of all sorts of things, and this puzzles
me because in one case we are discussing fully developed negatives/
slides while in the other completely undeveloped data.

But, as I said, maybe I am wrong and the latent response isn't linear.

Film is linear at the low end plus an offset (fog + transmission
of the emulsion), but at the high end, it is logarithmic because
once a grain has been excited by a photon, another photon
hitting the same grain won't add anything to the latent image.
This is what gives print film such high-end response without
saturating. (It typically takes a couple of photons to excite
a grain, but once done, the grain is no longer sensitive to
light; photons must hit other grains to contribute to the image.)

The standard curve applied in digital cameras is still linear
at the low end. See Figure 8a in the web page I gave.
So the shadows in a digital camera image shows linear
response when raw linear conversion, jpeg (without excessive
contrast added), or raw conversion with a standard curve applied.
That is different than shadows in film (print or slide) which
has the toe.

Roger

On Oct 14, 7:00 pm, "Roger N. Clark (change username to rnclark)"
wrote:
acl wrote:
I realise that. What I am trying to say is this: When one says that
digital capture is linear, one is referring to the raw data. The
equivalent object in film capture isn't a developed slide or negative,
but the latent image (before development). And, as far as I remember,
the effect there is also linearly related to the light
intensity*exposure time; it is after development that you get a
nonlinear response, just like after raw conversion you get a nonlinear
response (if you've applied a curve).

I say that because I keep seeing statement like "digital is linear and
film isn't" as explanations of all sorts of things, and this puzzles
me because in one case we are discussing fully developed negatives/
slides while in the other completely undeveloped data.

But, as I said, maybe I am wrong and the latent response isn't linear.

Film is linear at the low end plus an offset (fog + transmission
of the emulsion), but at the high end, it is logarithmic because
once a grain has been excited by a photon, another photon
hitting the same grain won't add anything to the latent image.
This is what gives print film such high-end response without
saturating.

Yes, that's the explanation for why highlights are so much easier on
film!

(It typically takes a couple of photons to excite
a grain, but once done, the grain is no longer sensitive to
light; photons must hit other grains to contribute to the image.)

Yes but until this (=you start getting many photons/grain during your
exposure) occurs, the response is linear. No?


The standard curve applied in digital cameras is still linear
at the low end. See Figure 8a in the web page I gave.
So the shadows in a digital camera image shows linear
response when raw linear conversion, jpeg (without excessive
contrast added), or raw conversion with a standard curve applied.
That is different than shadows in film (print or slide) which
has the toe.

Well as I tried to say twice, that, ie
So the shadows in a digital camera image shows linear
response when raw linear conversion, jpeg (without excessive
contrast added), or raw conversion with a standard curve applied.
has nothing to do with the fact that sensors respond linearly to
light, but is a result of the curve applied. No? Which is why I say
that how you convert is important.

acl wrote:
On Oct 14, 7:00 pm, "Roger N. Clark (change username to rnclark)"
wrote:

(It typically takes a couple of photons to excite
a grain, but once done, the grain is no longer sensitive to
light; photons must hit other grains to contribute to the image.)

Yes but until this (=you start getting many photons/grain during your
exposure) occurs, the response is linear. No?

It seems like it might be, but I'm not sure. See below.

The standard curve applied in digital cameras is still linear
at the low end. See Figure 8a in the web page I gave.
So the shadows in a digital camera image shows linear
response when raw linear conversion, jpeg (without excessive
contrast added), or raw conversion with a standard curve applied.
That is different than shadows in film (print or slide) which
has the toe.

Well as I tried to say twice, that, ie
So the shadows in a digital camera image shows linear
response when raw linear conversion, jpeg (without excessive
contrast added), or raw conversion with a standard curve applied.
has nothing to do with the fact that sensors respond linearly to
light, but is a result of the curve applied. No? Which is why I say
that how you convert is important.

I would say conversion is a post processing step so anything
can apply. One need not actually convert the raw data,
simply split the data out and get 3 images, one in red,
a second in green, and a third in blue, with no modification
or manipulation of the data.

It seems like film low level response might be linear,
but I can't see why chemically regarding the characteristic curve
it would change to a curve in the toe. So I don't know
what film does at the latent image stage. But does that
matter, as the latent image can not be viewed and must be
chemically processed to see, unlike digital camera raw data.
I don't think you can develop film, say Fuji Sensia,
or Tri-X and not get a curving toe.

Roger

On Oct 14, 9:55 pm, "Roger N. Clark (change username to rnclark)"
wrote:
acl wrote:
On Oct 14, 7:00 pm, "Roger N. Clark (change username to rnclark)"
wrote:
(It typically takes a couple of photons to excite
a grain, but once done, the grain is no longer sensitive to
light; photons must hit other grains to contribute to the image.)

Yes but until this (=you start getting many photons/grain during your
exposure) occurs, the response is linear. No?

It seems like it might be, but I'm not sure. See below.

In fact this thread got me interested again in this, but I could not
find anything very recent in a cursory search (there are review
articles from the 40s and so on, and a book that is also ancient). But
the Gurney-Mott paper seems to be the answer. I'll try to unearth it
again and read it.






The standard curve applied in digital cameras is still linear
at the low end. See Figure 8a in the web page I gave.
So the shadows in a digital camera image shows linear
response when raw linear conversion, jpeg (without excessive
contrast added), or raw conversion with a standard curve applied.
That is different than shadows in film (print or slide) which
has the toe.

Well as I tried to say twice, that, ie
So the shadows in a digital camera image shows linear
response when raw linear conversion, jpeg (without excessive
contrast added), or raw conversion with a standard curve applied.
has nothing to do with the fact that sensors respond linearly to
light, but is a result of the curve applied. No? Which is why I say
that how you convert is important.

I would say conversion is a post processing step so anything
can apply. One need not actually convert the raw data,
simply split the data out and get 3 images, one in red,
a second in green, and a third in blue, with no modification
or manipulation of the data.

It seems like film low level response might be linear,
but I can't see why chemically regarding the characteristic curve
it would change to a curve in the toe. So I don't know
what film does at the latent image stage. But does that
matter, as the latent image can not be viewed and must be
chemically processed to see, unlike digital camera raw data.
I don't think you can develop film, say Fuji Sensia,
or Tri-X and not get a curving toe.


Well I wasn't trying to make a philosophical point; I was trying to
say that the fact that the response at some point in the capture
process is linear doesn't directly result in "flat" or whatever
output. And I drew an analogy to illustrate what I mean, namely, that
film also seems to react linearly before development, so any
difference in the results can't be due to that (we ignore the
difference in high intensities).

Anyway, my response to the OP would be that canon compact cameras seem
to do better than others (that I tried, ie minolta and fuji) in terms
of colour. Or he can get a photoshop plug in or a program to take an
image and simulate some type of film (most are very bad though). Or
process it himself in photoshop, gimp, paintshop etc (I think
paintshop has automatic tools for this too). In short, play with the
various tools and techniques until it finally works like he wants.

Roger N. Clark (change username to rnclark) wrote:


It seems like film low level response might be linear,
but I can't see why chemically regarding the characteristic curve
it would change to a curve in the toe. So I don't know
what film does at the latent image stage. But does that
matter, as the latent image can not be viewed and must be
chemically processed to see, unlike digital camera raw data.
I don't think you can develop film, say Fuji Sensia,
or Tri-X and not get a curving toe.



Most B&W negative film is quite linear in the toe, and only
in the toe. Remember that it has fog. To see the linearity you
have to measure the transmission in the toe region, correct for
the possibility of overlapping grains if the transmission drops much below
85% (after compensation for surface reflection) and then
subtract off the background. Just before CCDs obsoleted film,
astrophotographers took multiple short exposures where the
transmission of the negative in regions of maximum broad field
density (i.e. excluding stars) was about 20 to 50%, scanned
them and added them together. This produced lower limiting
broad field density than using one long exposure, simply
because one no longer lost information to overlapping grains.
But it was very very ticklish business.

Doug McDonald