Megapixel vs. Zoom

"Mueen Nawaz" <m.nawaz.TakeThisOut@ieee.org> wrote in message
news:XaSdnecAktpAYsLYnZ2dnUVZ_sKdnZ2d@insightbb.com...
> Neil Harrington wrote:
>>> And perhaps that point may be reached even before you get to 100% crop
>>> if your sensor is small enough and you have way too many megapixels?
>>
>> I don't know what you mean by "100% crop" (how can you crop 100% of
>> anything?) but I'm sure you're right there too. However, I don't know how
>
> Sloppy language on my part.

Not just on your part. Others have used the term "100% crop" to mean some
small part of the photo is published on the Web at full resolution -- which
means of course that the whole photo can't all fit on the computer screen at
the same, unless it's a 2Mp image shown on a 1600x1200 monitor, or something
like that. So in that case it is a crop all right, but "100% crop" does not
seem properly descriptive to me.


> I meant if you're looking at it on the screen at 100% size (1:1 zoom).

I'm afraid I still don't get your meaning, unless you mean for example that
an object 10 inches high in the real world would be 10 inches high on the
monitor. But if that's what you mean I don't see how it has any bearing on
this.


> If you have lots and lots of megapixels, but still a small sensor, at some
> point the picture will get blurred at that scale because the sensor
> resolution is greater than that of the lensa (but will look just fine on
> an 8x10 or even bigger print).

I think there are two issues there. One is just as you suggest, the question
of whether a lens might be not able to match the resolution of the sensor.
Looking at the numbers, taking a 6Mp camera that uses a so-called 1/2.5"
type CCD, which is typically 5.76 mm and 2816 pixels in the long
dimension -- that's 489 pixels/mm. That seems like an extremely high
resolution relative to what a lens can be expected to do. I don't really
know what small digital camera lenses can do, but in 35mm it takes an
exceptionally sharp lens to resolve 80 line pairs/mm. So unless a small
digicam lens can do far better than that (which I doubt), it does seem that
the lens must run out of gas, so to speak, before the sensor does.

But it probably isn't that simple. I know that with film, there are
equations describing what final result in resolution can be expected from a
lens of x resolution and a film of y resolution. Neither one by itself sets
the limits of overall resolution, and even if you had a 100lp/mm lens and
100lp/mm film, you'd get substantially less than 100 line pairs/mm
resolution in the final image. And while you'd think a line pair might take
just two pixels on the sensor, I suspect it would really take more than
that, for a variety of reasons.

The other issue is how you're looking at the final image. As you indicate,
an 8x10 print is likely to look much better than the same image on a
computer screen. That's chiefly because you can actually get *all* the
pixels in the image on an 8x10 print, but you can't on a computer screen.
With a typical 17" or 19" LCD monitor, the maximum resolution is
1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
we're going to be throwing away a lot of those pixels as long as we're
viewing the image on a computer screen, regardless of the camera's sensor
size, and there's not much we can do about it. That's really a monitor
issue, not a camera issue.

Neil
 >> Stay informed about: Megapixel vs. Zoom 

"Mueen Nawaz" <m.nawaz.TakeThisOut@ieee.org> wrote in message
news:XaSdnecAktpAYsLYnZ2dnUVZ_sKdnZ2d@insightbb.com...
> Neil Harrington wrote:
>>> And perhaps that point may be reached even before you get to 100% crop
>>> if your sensor is small enough and you have way too many megapixels?
>>
>> I don't know what you mean by "100% crop" (how can you crop 100% of
>> anything?) but I'm sure you're right there too. However, I don't know how
>
> Sloppy language on my part.

Not just on your part. Others have used the term "100% crop" to mean some
small part of the photo is published on the Web at full resolution -- which
means of course that the whole photo can't all fit on the computer screen at
the same, unless it's a 2Mp image shown on a 1600x1200 monitor, or something
like that. So in that case it is a crop all right, but "100% crop" does not
seem properly descriptive to me.


> I meant if you're looking at it on the screen at 100% size (1:1 zoom).

I'm afraid I still don't get your meaning, unless you mean for example that
an object 10 inches high in the real world would be 10 inches high on the
monitor. But if that's what you mean I don't see how it has any bearing on
this.


> If you have lots and lots of megapixels, but still a small sensor, at some
> point the picture will get blurred at that scale because the sensor
> resolution is greater than that of the lensa (but will look just fine on
> an 8x10 or even bigger print).

I think there are two issues there. One is just as you suggest, the question
of whether a lens might be not able to match the resolution of the sensor.
Looking at the numbers, taking a 6Mp camera that uses a so-called 1/2.5"
type CCD, which is typically 5.76 mm and 2816 pixels in the long
dimension -- that's 489 pixels/mm. That seems like an extremely high
resolution relative to what a lens can be expected to do. I don't really
know what small digital camera lenses can do, but in 35mm it takes an
exceptionally sharp lens to resolve 80 line pairs/mm. So unless a small
digicam lens can do far better than that (which I doubt), it does seem that
the lens must run out of gas, so to speak, before the sensor does.

But it probably isn't that simple. I know that with film, there are
equations describing what final result in resolution can be expected from a
lens of x resolution and a film of y resolution. Neither one by itself sets
the limits of overall resolution, and even if you had a 100lp/mm lens and
100lp/mm film, you'd get substantially less than 100 line pairs/mm
resolution in the final image. And while you'd think a line pair might take
just two pixels on the sensor, I suspect it would really take more than
that, for a variety of reasons.

The other issue is how you're looking at the final image. As you indicate,
an 8x10 print is likely to look much better than the same image on a
computer screen. That's chiefly because you can actually get *all* the
pixels in the image on an 8x10 print, but you can't on a computer screen.
With a typical 17" or 19" LCD monitor, the maximum resolution is
1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
we're going to be throwing away a lot of those pixels as long as we're
viewing the image on a computer screen, regardless of the camera's sensor
size, and there's not much we can do about it. That's really a monitor
issue, not a camera issue.

Neil
 >> Stay informed about: Megapixel vs. Zoom 

"Mueen Nawaz" <m.nawaz.RemoveThis@ieee.org> wrote in message
news:XaSdnecAktpAYsLYnZ2dnUVZ_sKdnZ2d@insightbb.com...
> Neil Harrington wrote:
>>> And perhaps that point may be reached even before you get to 100% crop
>>> if your sensor is small enough and you have way too many megapixels?
>>
>> I don't know what you mean by "100% crop" (how can you crop 100% of
>> anything?) but I'm sure you're right there too. However, I don't know how
>
> Sloppy language on my part.

Not just on your part. Others have used the term "100% crop" to mean some
small part of the photo is published on the Web at full resolution -- which
means of course that the whole photo can't all fit on the computer screen at
the same, unless it's a 2Mp image shown on a 1600x1200 monitor, or something
like that. So in that case it is a crop all right, but "100% crop" does not
seem properly descriptive to me.


> I meant if you're looking at it on the screen at 100% size (1:1 zoom).

I'm afraid I still don't get your meaning, unless you mean for example that
an object 10 inches high in the real world would be 10 inches high on the
monitor. But if that's what you mean I don't see how it has any bearing on
this.


> If you have lots and lots of megapixels, but still a small sensor, at some
> point the picture will get blurred at that scale because the sensor
> resolution is greater than that of the lensa (but will look just fine on
> an 8x10 or even bigger print).

I think there are two issues there. One is just as you suggest, the question
of whether a lens might be not able to match the resolution of the sensor.
Looking at the numbers, taking a 6Mp camera that uses a so-called 1/2.5"
type CCD, which is typically 5.76 mm and 2816 pixels in the long
dimension -- that's 489 pixels/mm. That seems like an extremely high
resolution relative to what a lens can be expected to do. I don't really
know what small digital camera lenses can do, but in 35mm it takes an
exceptionally sharp lens to resolve 80 line pairs/mm. So unless a small
digicam lens can do far better than that (which I doubt), it does seem that
the lens must run out of gas, so to speak, before the sensor does.

But it probably isn't that simple. I know that with film, there are
equations describing what final result in resolution can be expected from a
lens of x resolution and a film of y resolution. Neither one by itself sets
the limits of overall resolution, and even if you had a 100lp/mm lens and
100lp/mm film, you'd get substantially less than 100 line pairs/mm
resolution in the final image. And while you'd think a line pair might take
just two pixels on the sensor, I suspect it would really take more than
that, for a variety of reasons.

The other issue is how you're looking at the final image. As you indicate,
an 8x10 print is likely to look much better than the same image on a
computer screen. That's chiefly because you can actually get *all* the
pixels in the image on an 8x10 print, but you can't on a computer screen.
With a typical 17" or 19" LCD monitor, the maximum resolution is
1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
we're going to be throwing away a lot of those pixels as long as we're
viewing the image on a computer screen, regardless of the camera's sensor
size, and there's not much we can do about it. That's really a monitor
issue, not a camera issue.

Neil
 >> Stay informed about: Megapixel vs. Zoom 

"Mueen Nawaz" <m.nawaz.DeleteThis@ieee.org> wrote in message
news:XaSdnecAktpAYsLYnZ2dnUVZ_sKdnZ2d@insightbb.com...
> Neil Harrington wrote:
>>> And perhaps that point may be reached even before you get to 100% crop
>>> if your sensor is small enough and you have way too many megapixels?
>>
>> I don't know what you mean by "100% crop" (how can you crop 100% of
>> anything?) but I'm sure you're right there too. However, I don't know how
>
> Sloppy language on my part.

Not just on your part. Others have used the term "100% crop" to mean some
small part of the photo is published on the Web at full resolution -- which
means of course that the whole photo can't all fit on the computer screen at
the same, unless it's a 2Mp image shown on a 1600x1200 monitor, or something
like that. So in that case it is a crop all right, but "100% crop" does not
seem properly descriptive to me.


> I meant if you're looking at it on the screen at 100% size (1:1 zoom).

I'm afraid I still don't get your meaning, unless you mean for example that
an object 10 inches high in the real world would be 10 inches high on the
monitor. But if that's what you mean I don't see how it has any bearing on
this.


> If you have lots and lots of megapixels, but still a small sensor, at some
> point the picture will get blurred at that scale because the sensor
> resolution is greater than that of the lensa (but will look just fine on
> an 8x10 or even bigger print).

I think there are two issues there. One is just as you suggest, the question
of whether a lens might be not able to match the resolution of the sensor.
Looking at the numbers, taking a 6Mp camera that uses a so-called 1/2.5"
type CCD, which is typically 5.76 mm and 2816 pixels in the long
dimension -- that's 489 pixels/mm. That seems like an extremely high
resolution relative to what a lens can be expected to do. I don't really
know what small digital camera lenses can do, but in 35mm it takes an
exceptionally sharp lens to resolve 80 line pairs/mm. So unless a small
digicam lens can do far better than that (which I doubt), it does seem that
the lens must run out of gas, so to speak, before the sensor does.

But it probably isn't that simple. I know that with film, there are
equations describing what final result in resolution can be expected from a
lens of x resolution and a film of y resolution. Neither one by itself sets
the limits of overall resolution, and even if you had a 100lp/mm lens and
100lp/mm film, you'd get substantially less than 100 line pairs/mm
resolution in the final image. And while you'd think a line pair might take
just two pixels on the sensor, I suspect it would really take more than
that, for a variety of reasons.

The other issue is how you're looking at the final image. As you indicate,
an 8x10 print is likely to look much better than the same image on a
computer screen. That's chiefly because you can actually get *all* the
pixels in the image on an 8x10 print, but you can't on a computer screen.
With a typical 17" or 19" LCD monitor, the maximum resolution is
1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
we're going to be throwing away a lot of those pixels as long as we're
viewing the image on a computer screen, regardless of the camera's sensor
size, and there's not much we can do about it. That's really a monitor
issue, not a camera issue.

Neil
 >> Stay informed about: Megapixel vs. Zoom 

"Mueen Nawaz" <m.nawaz RemoveThis @ieee.org> wrote in message
news:XaSdnecAktpAYsLYnZ2dnUVZ_sKdnZ2d@insightbb.com...
> Neil Harrington wrote:
>>> And perhaps that point may be reached even before you get to 100% crop
>>> if your sensor is small enough and you have way too many megapixels?
>>
>> I don't know what you mean by "100% crop" (how can you crop 100% of
>> anything?) but I'm sure you're right there too. However, I don't know how
>
> Sloppy language on my part.

Not just on your part. Others have used the term "100% crop" to mean some
small part of the photo is published on the Web at full resolution -- which
means of course that the whole photo can't all fit on the computer screen at
the same, unless it's a 2Mp image shown on a 1600x1200 monitor, or something
like that. So in that case it is a crop all right, but "100% crop" does not
seem properly descriptive to me.


> I meant if you're looking at it on the screen at 100% size (1:1 zoom).

I'm afraid I still don't get your meaning, unless you mean for example that
an object 10 inches high in the real world would be 10 inches high on the
monitor. But if that's what you mean I don't see how it has any bearing on
this.


> If you have lots and lots of megapixels, but still a small sensor, at some
> point the picture will get blurred at that scale because the sensor
> resolution is greater than that of the lensa (but will look just fine on
> an 8x10 or even bigger print).

I think there are two issues there. One is just as you suggest, the question
of whether a lens might be not able to match the resolution of the sensor.
Looking at the numbers, taking a 6Mp camera that uses a so-called 1/2.5"
type CCD, which is typically 5.76 mm and 2816 pixels in the long
dimension -- that's 489 pixels/mm. That seems like an extremely high
resolution relative to what a lens can be expected to do. I don't really
know what small digital camera lenses can do, but in 35mm it takes an
exceptionally sharp lens to resolve 80 line pairs/mm. So unless a small
digicam lens can do far better than that (which I doubt), it does seem that
the lens must run out of gas, so to speak, before the sensor does.

But it probably isn't that simple. I know that with film, there are
equations describing what final result in resolution can be expected from a
lens of x resolution and a film of y resolution. Neither one by itself sets
the limits of overall resolution, and even if you had a 100lp/mm lens and
100lp/mm film, you'd get substantially less than 100 line pairs/mm
resolution in the final image. And while you'd think a line pair might take
just two pixels on the sensor, I suspect it would really take more than
that, for a variety of reasons.

The other issue is how you're looking at the final image. As you indicate,
an 8x10 print is likely to look much better than the same image on a
computer screen. That's chiefly because you can actually get *all* the
pixels in the image on an 8x10 print, but you can't on a computer screen.
With a typical 17" or 19" LCD monitor, the maximum resolution is
1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
we're going to be throwing away a lot of those pixels as long as we're
viewing the image on a computer screen, regardless of the camera's sensor
size, and there's not much we can do about it. That's really a monitor
issue, not a camera issue.

Neil
 >> Stay informed about: Megapixel vs. Zoom 

Neil Harrington <not.DeleteThis@home.today> wrote:

: "Mueen Nawaz" <m.nawaz.DeleteThis@ieee.org> wrote in message

: > I meant if you're looking at it on the screen at 100% size (1:1 zoom).

: I'm afraid I still don't get your meaning, unless you mean for example that
: an object 10 inches high in the real world would be 10 inches high on the
: monitor. But if that's what you mean I don't see how it has any bearing on
: this.

I think he ie refering to a relationship of one screen pixel representing
one pixel from the image data. When using the various PS products this is
called a 100% zoom or "actual pixels". The size on the screen has nothing
to do with the size of the object in real life, or even on the resulting
print. Such a RL to screen relationship would be nearly meaningless since
the size of the screen and the resolution of the screen will determine the
screen dimension of an object of a specific dimensions in pixels. And when
you include the relationship of RL object to pixel dimension with a
particular lens length and sensor resolution the number of variables can
be daunting. And this becomes even more crazy when you throw in the
relationship of screen size to print size. Different screen
resolutions/zoom sizes translated through the print driver and printer to
some highly variable choices of print dimensions compounds the problem.
True, if you have all the variables and math it should be easy to predict
RL to Screen to print dimension relationships, but there is very little
need (short of a CSI investigation trying to measure the length of a
weapon from a fuzzy photo) for most of us to worry about or care about
such equations.

If I am displaying an image at 300% so I can do some very fine editing, I
will not expect the image to be perfectly sharp. I expect that the image
to look as if it is made up of individual squares. On the other hand if my
image shows strong pixelation when it is being displayed at 50% resolution
I know there is a problem either with the display program/device or with
the image data.

: The other issue is how you're looking at the final image. As you indicate,
: an 8x10 print is likely to look much better than the same image on a
: computer screen. That's chiefly because you can actually get *all* the
: pixels in the image on an 8x10 print, but you can't on a computer screen.
: With a typical 17" or 19" LCD monitor, the maximum resolution is
: 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
: 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
: we're going to be throwing away a lot of those pixels as long as we're
: viewing the image on a computer screen, regardless of the camera's sensor
: size, and there's not much we can do about it. That's really a monitor
: issue, not a camera issue.

True,as far as you go. But since an image can be displayed much larger
than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
pixel shown on a 1.3 mp screen will still work. The screen will just be a
small window onto the much larger image that can be shifted around the
image to reveal different parts of the image. Display on a screen is not
limited to an image that can be shown on the screen all at once. But a
single dot on the screen will be much larger in RL physical dimensions
that a single dot on the print. If a print was made at the same resolution
at the same physical dimensions as the screen very few of us would count
it acceptable. What looks good and is acceptable on a screen is nowhere
near good enough for a print.

How many of us would look at a printed image that has just over 1000 lines
of resolution in a print 2 feet tall and call it sharp and clear (an
equivalent of about 41 dpi). But if you get a medium sized HD Plasma
Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
sharp and spectacular the image is.

Randy

==========
Randy Berbaum
Champaign, IL
 >> Stay informed about: Megapixel vs. Zoom 

Neil Harrington <not DeleteThis @home.today> wrote:

: "Mueen Nawaz" <m.nawaz DeleteThis @ieee.org> wrote in message

: > I meant if you're looking at it on the screen at 100% size (1:1 zoom).

: I'm afraid I still don't get your meaning, unless you mean for example that
: an object 10 inches high in the real world would be 10 inches high on the
: monitor. But if that's what you mean I don't see how it has any bearing on
: this.

I think he ie refering to a relationship of one screen pixel representing
one pixel from the image data. When using the various PS products this is
called a 100% zoom or "actual pixels". The size on the screen has nothing
to do with the size of the object in real life, or even on the resulting
print. Such a RL to screen relationship would be nearly meaningless since
the size of the screen and the resolution of the screen will determine the
screen dimension of an object of a specific dimensions in pixels. And when
you include the relationship of RL object to pixel dimension with a
particular lens length and sensor resolution the number of variables can
be daunting. And this becomes even more crazy when you throw in the
relationship of screen size to print size. Different screen
resolutions/zoom sizes translated through the print driver and printer to
some highly variable choices of print dimensions compounds the problem.
True, if you have all the variables and math it should be easy to predict
RL to Screen to print dimension relationships, but there is very little
need (short of a CSI investigation trying to measure the length of a
weapon from a fuzzy photo) for most of us to worry about or care about
such equations.

If I am displaying an image at 300% so I can do some very fine editing, I
will not expect the image to be perfectly sharp. I expect that the image
to look as if it is made up of individual squares. On the other hand if my
image shows strong pixelation when it is being displayed at 50% resolution
I know there is a problem either with the display program/device or with
the image data.

: The other issue is how you're looking at the final image. As you indicate,
: an 8x10 print is likely to look much better than the same image on a
: computer screen. That's chiefly because you can actually get *all* the
: pixels in the image on an 8x10 print, but you can't on a computer screen.
: With a typical 17" or 19" LCD monitor, the maximum resolution is
: 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
: 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
: we're going to be throwing away a lot of those pixels as long as we're
: viewing the image on a computer screen, regardless of the camera's sensor
: size, and there's not much we can do about it. That's really a monitor
: issue, not a camera issue.

True,as far as you go. But since an image can be displayed much larger
than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
pixel shown on a 1.3 mp screen will still work. The screen will just be a
small window onto the much larger image that can be shifted around the
image to reveal different parts of the image. Display on a screen is not
limited to an image that can be shown on the screen all at once. But a
single dot on the screen will be much larger in RL physical dimensions
that a single dot on the print. If a print was made at the same resolution
at the same physical dimensions as the screen very few of us would count
it acceptable. What looks good and is acceptable on a screen is nowhere
near good enough for a print.

How many of us would look at a printed image that has just over 1000 lines
of resolution in a print 2 feet tall and call it sharp and clear (an
equivalent of about 41 dpi). But if you get a medium sized HD Plasma
Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
sharp and spectacular the image is.

Randy

==========
Randy Berbaum
Champaign, IL
 >> Stay informed about: Megapixel vs. Zoom 

Neil Harrington <not.TakeThisOut@home.today> wrote:

: "Mueen Nawaz" <m.nawaz.TakeThisOut@ieee.org> wrote in message

: > I meant if you're looking at it on the screen at 100% size (1:1 zoom).

: I'm afraid I still don't get your meaning, unless you mean for example that
: an object 10 inches high in the real world would be 10 inches high on the
: monitor. But if that's what you mean I don't see how it has any bearing on
: this.

I think he ie refering to a relationship of one screen pixel representing
one pixel from the image data. When using the various PS products this is
called a 100% zoom or "actual pixels". The size on the screen has nothing
to do with the size of the object in real life, or even on the resulting
print. Such a RL to screen relationship would be nearly meaningless since
the size of the screen and the resolution of the screen will determine the
screen dimension of an object of a specific dimensions in pixels. And when
you include the relationship of RL object to pixel dimension with a
particular lens length and sensor resolution the number of variables can
be daunting. And this becomes even more crazy when you throw in the
relationship of screen size to print size. Different screen
resolutions/zoom sizes translated through the print driver and printer to
some highly variable choices of print dimensions compounds the problem.
True, if you have all the variables and math it should be easy to predict
RL to Screen to print dimension relationships, but there is very little
need (short of a CSI investigation trying to measure the length of a
weapon from a fuzzy photo) for most of us to worry about or care about
such equations.

If I am displaying an image at 300% so I can do some very fine editing, I
will not expect the image to be perfectly sharp. I expect that the image
to look as if it is made up of individual squares. On the other hand if my
image shows strong pixelation when it is being displayed at 50% resolution
I know there is a problem either with the display program/device or with
the image data.

: The other issue is how you're looking at the final image. As you indicate,
: an 8x10 print is likely to look much better than the same image on a
: computer screen. That's chiefly because you can actually get *all* the
: pixels in the image on an 8x10 print, but you can't on a computer screen.
: With a typical 17" or 19" LCD monitor, the maximum resolution is
: 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
: 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
: we're going to be throwing away a lot of those pixels as long as we're
: viewing the image on a computer screen, regardless of the camera's sensor
: size, and there's not much we can do about it. That's really a monitor
: issue, not a camera issue.

True,as far as you go. But since an image can be displayed much larger
than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
pixel shown on a 1.3 mp screen will still work. The screen will just be a
small window onto the much larger image that can be shifted around the
image to reveal different parts of the image. Display on a screen is not
limited to an image that can be shown on the screen all at once. But a
single dot on the screen will be much larger in RL physical dimensions
that a single dot on the print. If a print was made at the same resolution
at the same physical dimensions as the screen very few of us would count
it acceptable. What looks good and is acceptable on a screen is nowhere
near good enough for a print.

How many of us would look at a printed image that has just over 1000 lines
of resolution in a print 2 feet tall and call it sharp and clear (an
equivalent of about 41 dpi). But if you get a medium sized HD Plasma
Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
sharp and spectacular the image is.

Randy

==========
Randy Berbaum
Champaign, IL
 >> Stay informed about: Megapixel vs. Zoom 

Neil Harrington <not.DeleteThis@home.today> wrote:

: "Mueen Nawaz" <m.nawaz.DeleteThis@ieee.org> wrote in message

: > I meant if you're looking at it on the screen at 100% size (1:1 zoom).

: I'm afraid I still don't get your meaning, unless you mean for example that
: an object 10 inches high in the real world would be 10 inches high on the
: monitor. But if that's what you mean I don't see how it has any bearing on
: this.

I think he ie refering to a relationship of one screen pixel representing
one pixel from the image data. When using the various PS products this is
called a 100% zoom or "actual pixels". The size on the screen has nothing
to do with the size of the object in real life, or even on the resulting
print. Such a RL to screen relationship would be nearly meaningless since
the size of the screen and the resolution of the screen will determine the
screen dimension of an object of a specific dimensions in pixels. And when
you include the relationship of RL object to pixel dimension with a
particular lens length and sensor resolution the number of variables can
be daunting. And this becomes even more crazy when you throw in the
relationship of screen size to print size. Different screen
resolutions/zoom sizes translated through the print driver and printer to
some highly variable choices of print dimensions compounds the problem.
True, if you have all the variables and math it should be easy to predict
RL to Screen to print dimension relationships, but there is very little
need (short of a CSI investigation trying to measure the length of a
weapon from a fuzzy photo) for most of us to worry about or care about
such equations.

If I am displaying an image at 300% so I can do some very fine editing, I
will not expect the image to be perfectly sharp. I expect that the image
to look as if it is made up of individual squares. On the other hand if my
image shows strong pixelation when it is being displayed at 50% resolution
I know there is a problem either with the display program/device or with
the image data.

: The other issue is how you're looking at the final image. As you indicate,
: an 8x10 print is likely to look much better than the same image on a
: computer screen. That's chiefly because you can actually get *all* the
: pixels in the image on an 8x10 print, but you can't on a computer screen.
: With a typical 17" or 19" LCD monitor, the maximum resolution is
: 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
: 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
: we're going to be throwing away a lot of those pixels as long as we're
: viewing the image on a computer screen, regardless of the camera's sensor
: size, and there's not much we can do about it. That's really a monitor
: issue, not a camera issue.

True,as far as you go. But since an image can be displayed much larger
than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
pixel shown on a 1.3 mp screen will still work. The screen will just be a
small window onto the much larger image that can be shifted around the
image to reveal different parts of the image. Display on a screen is not
limited to an image that can be shown on the screen all at once. But a
single dot on the screen will be much larger in RL physical dimensions
that a single dot on the print. If a print was made at the same resolution
at the same physical dimensions as the screen very few of us would count
it acceptable. What looks good and is acceptable on a screen is nowhere
near good enough for a print.

How many of us would look at a printed image that has just over 1000 lines
of resolution in a print 2 feet tall and call it sharp and clear (an
equivalent of about 41 dpi). But if you get a medium sized HD Plasma
Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
sharp and spectacular the image is.

Randy

==========
Randy Berbaum
Champaign, IL
 >> Stay informed about: Megapixel vs. Zoom 

Neil Harrington <not.TakeThisOut@home.today> wrote:

: "Mueen Nawaz" <m.nawaz.TakeThisOut@ieee.org> wrote in message

: > I meant if you're looking at it on the screen at 100% size (1:1 zoom).

: I'm afraid I still don't get your meaning, unless you mean for example that
: an object 10 inches high in the real world would be 10 inches high on the
: monitor. But if that's what you mean I don't see how it has any bearing on
: this.

I think he ie refering to a relationship of one screen pixel representing
one pixel from the image data. When using the various PS products this is
called a 100% zoom or "actual pixels". The size on the screen has nothing
to do with the size of the object in real life, or even on the resulting
print. Such a RL to screen relationship would be nearly meaningless since
the size of the screen and the resolution of the screen will determine the
screen dimension of an object of a specific dimensions in pixels. And when
you include the relationship of RL object to pixel dimension with a
particular lens length and sensor resolution the number of variables can
be daunting. And this becomes even more crazy when you throw in the
relationship of screen size to print size. Different screen
resolutions/zoom sizes translated through the print driver and printer to
some highly variable choices of print dimensions compounds the problem.
True, if you have all the variables and math it should be easy to predict
RL to Screen to print dimension relationships, but there is very little
need (short of a CSI investigation trying to measure the length of a
weapon from a fuzzy photo) for most of us to worry about or care about
such equations.

If I am displaying an image at 300% so I can do some very fine editing, I
will not expect the image to be perfectly sharp. I expect that the image
to look as if it is made up of individual squares. On the other hand if my
image shows strong pixelation when it is being displayed at 50% resolution
I know there is a problem either with the display program/device or with
the image data.

: The other issue is how you're looking at the final image. As you indicate,
: an 8x10 print is likely to look much better than the same image on a
: computer screen. That's chiefly because you can actually get *all* the
: pixels in the image on an 8x10 print, but you can't on a computer screen.
: With a typical 17" or 19" LCD monitor, the maximum resolution is
: 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
: 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
: we're going to be throwing away a lot of those pixels as long as we're
: viewing the image on a computer screen, regardless of the camera's sensor
: size, and there's not much we can do about it. That's really a monitor
: issue, not a camera issue.

True,as far as you go. But since an image can be displayed much larger
than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
pixel shown on a 1.3 mp screen will still work. The screen will just be a
small window onto the much larger image that can be shifted around the
image to reveal different parts of the image. Display on a screen is not
limited to an image that can be shown on the screen all at once. But a
single dot on the screen will be much larger in RL physical dimensions
that a single dot on the print. If a print was made at the same resolution
at the same physical dimensions as the screen very few of us would count
it acceptable. What looks good and is acceptable on a screen is nowhere
near good enough for a print.

How many of us would look at a printed image that has just over 1000 lines
of resolution in a print 2 feet tall and call it sharp and clear (an
equivalent of about 41 dpi). But if you get a medium sized HD Plasma
Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
sharp and spectacular the image is.

Randy

==========
Randy Berbaum
Champaign, IL
 >> Stay informed about: Megapixel vs. Zoom 

Neil Harrington <not.RemoveThis@home.today> wrote:

: "Mueen Nawaz" <m.nawaz.RemoveThis@ieee.org> wrote in message

: > I meant if you're looking at it on the screen at 100% size (1:1 zoom).

: I'm afraid I still don't get your meaning, unless you mean for example that
: an object 10 inches high in the real world would be 10 inches high on the
: monitor. But if that's what you mean I don't see how it has any bearing on
: this.

I think he ie refering to a relationship of one screen pixel representing
one pixel from the image data. When using the various PS products this is
called a 100% zoom or "actual pixels". The size on the screen has nothing
to do with the size of the object in real life, or even on the resulting
print. Such a RL to screen relationship would be nearly meaningless since
the size of the screen and the resolution of the screen will determine the
screen dimension of an object of a specific dimensions in pixels. And when
you include the relationship of RL object to pixel dimension with a
particular lens length and sensor resolution the number of variables can
be daunting. And this becomes even more crazy when you throw in the
relationship of screen size to print size. Different screen
resolutions/zoom sizes translated through the print driver and printer to
some highly variable choices of print dimensions compounds the problem.
True, if you have all the variables and math it should be easy to predict
RL to Screen to print dimension relationships, but there is very little
need (short of a CSI investigation trying to measure the length of a
weapon from a fuzzy photo) for most of us to worry about or care about
such equations.

If I am displaying an image at 300% so I can do some very fine editing, I
will not expect the image to be perfectly sharp. I expect that the image
to look as if it is made up of individual squares. On the other hand if my
image shows strong pixelation when it is being displayed at 50% resolution
I know there is a problem either with the display program/device or with
the image data.

: The other issue is how you're looking at the final image. As you indicate,
: an 8x10 print is likely to look much better than the same image on a
: computer screen. That's chiefly because you can actually get *all* the
: pixels in the image on an 8x10 print, but you can't on a computer screen.
: With a typical 17" or 19" LCD monitor, the maximum resolution is
: 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
: 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp camera
: we're going to be throwing away a lot of those pixels as long as we're
: viewing the image on a computer screen, regardless of the camera's sensor
: size, and there's not much we can do about it. That's really a monitor
: issue, not a camera issue.

True,as far as you go. But since an image can be displayed much larger
than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
pixel shown on a 1.3 mp screen will still work. The screen will just be a
small window onto the much larger image that can be shifted around the
image to reveal different parts of the image. Display on a screen is not
limited to an image that can be shown on the screen all at once. But a
single dot on the screen will be much larger in RL physical dimensions
that a single dot on the print. If a print was made at the same resolution
at the same physical dimensions as the screen very few of us would count
it acceptable. What looks good and is acceptable on a screen is nowhere
near good enough for a print.

How many of us would look at a printed image that has just over 1000 lines
of resolution in a print 2 feet tall and call it sharp and clear (an
equivalent of about 41 dpi). But if you get a medium sized HD Plasma
Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
sharp and spectacular the image is.

Randy

==========
Randy Berbaum
Champaign, IL
 >> Stay informed about: Megapixel vs. Zoom 

"Randy Berbaum" <rberbaum.DeleteThis@bluestem.prairienet.org> wrote in message
news:ejrfbs$kv1$1@wildfire.prairienet.org...
> Neil Harrington <not.DeleteThis@home.today> wrote:
>
> : "Mueen Nawaz" <m.nawaz.DeleteThis@ieee.org> wrote in message
>
> : > I meant if you're looking at it on the screen at 100% size (1:1 zoom).
>
> : I'm afraid I still don't get your meaning, unless you mean for example
> that
> : an object 10 inches high in the real world would be 10 inches high on
> the
> : monitor. But if that's what you mean I don't see how it has any bearing
> on
> : this.
>
> I think he ie refering to a relationship of one screen pixel representing
> one pixel from the image data. When using the various PS products this is
> called a 100% zoom or "actual pixels".

As mentioned, I have seen "100% zoom" used to mean that, but that wasn't my
impression from what he wrote. I think "actual pixels" is the more
descriptive term. I don't use PS so wasn't aware that they used "100% zoom"
in that way. Perhaps that's where the usage comes from.


> The size on the screen has nothing
> to do with the size of the object in real life, or even on the resulting
> print. Such a RL to screen relationship would be nearly meaningless since
> the size of the screen and the resolution of the screen will determine the
> screen dimension of an object of a specific dimensions in pixels.

Right.


> And when
> you include the relationship of RL object to pixel dimension with a
> particular lens length and sensor resolution the number of variables can
> be daunting. And this becomes even more crazy when you throw in the
> relationship of screen size to print size. Different screen
> resolutions/zoom sizes translated through the print driver and printer to
> some highly variable choices of print dimensions compounds the problem.
> True, if you have all the variables and math it should be easy to predict
> RL to Screen to print dimension relationships, but there is very little
> need (short of a CSI investigation trying to measure the length of a
> weapon from a fuzzy photo) for most of us to worry about or care about
> such equations.
>
> If I am displaying an image at 300% so I can do some very fine editing, I
> will not expect the image to be perfectly sharp. I expect that the image
> to look as if it is made up of individual squares. On the other hand if my
> image shows strong pixelation when it is being displayed at 50% resolution
> I know there is a problem either with the display program/device or with
> the image data.

You're using these percentages in a sense consistent with "100%" meaning
nothing more or less than "all the original image pixels," correct? So your
"50% resolution" would mean what, one pixel on screen for every two pixels
*linearly* in the original image?


>
> : The other issue is how you're looking at the final image. As you
> indicate,
> : an 8x10 print is likely to look much better than the same image on a
> : computer screen. That's chiefly because you can actually get *all* the
> : pixels in the image on an 8x10 print, but you can't on a computer
> screen.
> : With a typical 17" or 19" LCD monitor, the maximum resolution is
> : 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
> : 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp
> camera
> : we're going to be throwing away a lot of those pixels as long as we're
> : viewing the image on a computer screen, regardless of the camera's
> sensor
> : size, and there's not much we can do about it. That's really a monitor
> : issue, not a camera issue.
>
> True,as far as you go. But since an image can be displayed much larger
> than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
> pixel shown on a 1.3 mp screen will still work. The screen will just be a
> small window onto the much larger image that can be shifted around the
> image to reveal different parts of the image.

Sure. That is in fact exactly how I look at some of the images published on
the Web from different cameras/lenses, when the page allows such viewing.
Looking at the full image that's been made to fit the screen is practically
meaningless for purposes of comparison, so much information having been
thrown away.


> Display on a screen is not
> limited to an image that can be shown on the screen all at once. But a
> single dot on the screen will be much larger in RL physical dimensions
> that a single dot on the print. If a print was made at the same resolution
> at the same physical dimensions as the screen very few of us would count
> it acceptable. What looks good and is acceptable on a screen is nowhere
> near good enough for a print.
>
> How many of us would look at a printed image that has just over 1000 lines
> of resolution in a print 2 feet tall and call it sharp and clear (an
> equivalent of about 41 dpi). But if you get a medium sized HD Plasma
> Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
> sharp and spectacular the image is.

Sure. Mostly because of the usual difference in the viewing distance.

Neil
 >> Stay informed about: Megapixel vs. Zoom 

"Randy Berbaum" <rberbaum.RemoveThis@bluestem.prairienet.org> wrote in message
news:ejrfbs$kv1$1@wildfire.prairienet.org...
> Neil Harrington <not.RemoveThis@home.today> wrote:
>
> : "Mueen Nawaz" <m.nawaz.RemoveThis@ieee.org> wrote in message
>
> : > I meant if you're looking at it on the screen at 100% size (1:1 zoom).
>
> : I'm afraid I still don't get your meaning, unless you mean for example
> that
> : an object 10 inches high in the real world would be 10 inches high on
> the
> : monitor. But if that's what you mean I don't see how it has any bearing
> on
> : this.
>
> I think he ie refering to a relationship of one screen pixel representing
> one pixel from the image data. When using the various PS products this is
> called a 100% zoom or "actual pixels".

As mentioned, I have seen "100% zoom" used to mean that, but that wasn't my
impression from what he wrote. I think "actual pixels" is the more
descriptive term. I don't use PS so wasn't aware that they used "100% zoom"
in that way. Perhaps that's where the usage comes from.


> The size on the screen has nothing
> to do with the size of the object in real life, or even on the resulting
> print. Such a RL to screen relationship would be nearly meaningless since
> the size of the screen and the resolution of the screen will determine the
> screen dimension of an object of a specific dimensions in pixels.

Right.


> And when
> you include the relationship of RL object to pixel dimension with a
> particular lens length and sensor resolution the number of variables can
> be daunting. And this becomes even more crazy when you throw in the
> relationship of screen size to print size. Different screen
> resolutions/zoom sizes translated through the print driver and printer to
> some highly variable choices of print dimensions compounds the problem.
> True, if you have all the variables and math it should be easy to predict
> RL to Screen to print dimension relationships, but there is very little
> need (short of a CSI investigation trying to measure the length of a
> weapon from a fuzzy photo) for most of us to worry about or care about
> such equations.
>
> If I am displaying an image at 300% so I can do some very fine editing, I
> will not expect the image to be perfectly sharp. I expect that the image
> to look as if it is made up of individual squares. On the other hand if my
> image shows strong pixelation when it is being displayed at 50% resolution
> I know there is a problem either with the display program/device or with
> the image data.

You're using these percentages in a sense consistent with "100%" meaning
nothing more or less than "all the original image pixels," correct? So your
"50% resolution" would mean what, one pixel on screen for every two pixels
*linearly* in the original image?


>
> : The other issue is how you're looking at the final image. As you
> indicate,
> : an 8x10 print is likely to look much better than the same image on a
> : computer screen. That's chiefly because you can actually get *all* the
> : pixels in the image on an 8x10 print, but you can't on a computer
> screen.
> : With a typical 17" or 19" LCD monitor, the maximum resolution is
> : 1280x1024 -- which is only 1.3 megapixels. Even a monitor that will do
> : 1600x1200 is only putting 2 Mp on the screen. So with a 6, 8 or 10Mp
> camera
> : we're going to be throwing away a lot of those pixels as long as we're
> : viewing the image on a computer screen, regardless of the camera's
> sensor
> : size, and there's not much we can do about it. That's really a monitor
> : issue, not a camera issue.
>
> True,as far as you go. But since an image can be displayed much larger
> than the size of the screen, a 10mp displayed at a 1 screen pixel=1 image
> pixel shown on a 1.3 mp screen will still work. The screen will just be a
> small window onto the much larger image that can be shifted around the
> image to reveal different parts of the image.

Sure. That is in fact exactly how I look at some of the images published on
the Web from different cameras/lenses, when the page allows such viewing.
Looking at the full image that's been made to fit the screen is practically
meaningless for purposes of comparison, so much information having been
thrown away.


> Display on a screen is not
> limited to an image that can be shown on the screen all at once. But a
> single dot on the screen will be much larger in RL physical dimensions
> that a single dot on the print. If a print was made at the same resolution
> at the same physical dimensions as the screen very few of us would count
> it acceptable. What looks good and is acceptable on a screen is nowhere
> near good enough for a print.
>
> How many of us would look at a printed image that has just over 1000 lines
> of resolution in a print 2 feet tall and call it sharp and clear (an
> equivalent of about 41 dpi). But if you get a medium sized HD Plasma
> Screen with a 2' tall picture people will be OOoo'ing and wow'ing at how
> sharp and spectacular the image is.

Sure. Mostly because of the usual difference in the viewing distance.

Neil
 >> Stay informed about: Megapixel vs. Zoom