Newbie question : meaning of "100% crop" ?

For some time since I bought a digital camera and started
reviving my interest in photography, I was puzzled by the
expression which pops up now and then. I've never seen a
definition (maybe I didn't look very hard), but I've made
my own deduction.

I think it means a crop from the original image, the
original pixel count of the cropped section being retained
without resizing it.

E.g., if I cut out a 500x400 section from a 2560x1920 (5MP)
image and save it as a 500x400 picture, that's a 100% crop.
Is this correct ?

Yup. Correct.

When an image is downsized, it hides things. A 100% crop shows part of the
actual image at full size.


wrote in message
ups.com...
For some time since I bought a digital camera and started
reviving my interest in photography, I was puzzled by the
expression which pops up now and then. I've never seen a
definition (maybe I didn't look very hard), but I've made
my own deduction.

I think it means a crop from the original image, the
original pixel count of the cropped section being retained
without resizing it.

E.g., if I cut out a 500x400 section from a 2560x1920 (5MP)
image and save it as a 500x400 picture, that's a 100% crop.
Is this correct ?

wrote in message
ups.com...


E.g., if I cut out a 500x400 section from a 2560x1920 (5MP)
image and save it as a 500x400 picture, that's a 100% crop.
Is this correct ?


You got it. The cropped out section is the same size as it was in the
original full size image.

Helen wrote:
wrote in message
ups.com...

E.g., if I cut out a 500x400 section from a 2560x1920 (5MP)
image and save it as a 500x400 picture, that's a 100% crop.
Is this correct ?


You got it. The cropped out section is the same size as it was in the
original full size image.


Somehow the whole term seems like an oxymoron. What is the crop 100% OF?

On Thu, 13 Jul 2006 02:32:41 -0500, Ron Hunter
wrote:

Helen wrote:
wrote in message
ups.com...

E.g., if I cut out a 500x400 section from a 2560x1920 (5MP)
image and save it as a 500x400 picture, that's a 100% crop.
Is this correct ?


You got it. The cropped out section is the same size as it was in the
original full size image.


Somehow the whole term seems like an oxymoron. What is the crop 100% OF?

It's 100% of the pixel count - in other words the original
pixels, not a re-scaling of any sort.


--
John Bean

In article , John Bean wrote:
Somehow the whole term seems like an oxymoron. What is the crop 100% OF?

It's 100% of the pixel count - in other words the original
pixels, not a re-scaling of any sort.

So is it the same number of pixels as the original file or is it a smaller
number?

Roger

In article , John Bean
writes
On Thu, 13 Jul 2006 02:32:41 -0500, Ron Hunter
wrote:

Helen wrote:
wrote in message
ups.com...

E.g., if I cut out a 500x400 section from a 2560x1920 (5MP)
image and save it as a 500x400 picture, that's a 100% crop.
Is this correct ?


You got it. The cropped out section is the same size as it was in the
original full size image.


Somehow the whole term seems like an oxymoron. What is the crop 100% OF?

It's 100% of the pixel count - in other words the original
pixels, not a re-scaling of any sort.

Which leads to the conclusion that if you up-sample by a factor of two
the linear pixel count you will have a 400% crop, which is utter
nonsense. If I take a 50% cut or crop of something I have half of it
i.e. 50% of one pound sterling, it is nonsense to then say that my half
is 100%. Just say that it is a crop at native resolution, or that it has
not been re-sampled. In fact why not only state what you have changed,
if I publish a picture I should not have to list all the alterations I
have not made.

--
Ian G8ILZ

Prometheus wrote:

In article , John Bean
writes
On Thu, 13 Jul 2006 02:32:41 -0500, Ron Hunter
wrote:

Helen wrote:
wrote in message
ups.com...

E.g., if I cut out a 500x400 section from a 2560x1920 (5MP)
image and save it as a 500x400 picture, that's a 100% crop.
Is this correct ?


You got it. The cropped out section is the same size as it was in the
original full size image.


Somehow the whole term seems like an oxymoron. What is the crop 100% OF?

It's 100% of the pixel count - in other words the original
pixels, not a re-scaling of any sort.

Which leads to the conclusion that if you up-sample by a factor of two
the linear pixel count you will have a 400% crop, which is utter
nonsense. If I take a 50% cut or crop of something I have half of it
i.e. 50% of one pound sterling, it is nonsense to then say that my half
is 100%. Just say that it is a crop at native resolution, or that it has
not been re-sampled. In fact why not only state what you have changed,
if I publish a picture I should not have to list all the alterations I
have not made.

Why not just think of the phrase as a name or technical
term instead of a descriptive one ? There are plenty of
examples where what started out as an attempt to describe
something evolved (and often condensed) into something
that's rather meaningless by itself. For instance, we speak
of the DOF of a two-dimensional picture, and white balance
when there's not a single white spot. The "spider" (inner
suspension) of a speaker has not resembled a spider in
appearance for the better part of a century.

In article . com,
writes

Prometheus wrote:

In article , John Bean
writes
On Thu, 13 Jul 2006 02:32:41 -0500, Ron Hunter
wrote:
----------Cut----------------
Somehow the whole term seems like an oxymoron. What is the crop 100% OF?

It's 100% of the pixel count - in other words the original
pixels, not a re-scaling of any sort.

Which leads to the conclusion that if you up-sample by a factor of two
the linear pixel count you will have a 400% crop, which is utter
nonsense. If I take a 50% cut or crop of something I have half of it
i.e. 50% of one pound sterling, it is nonsense to then say that my half
is 100%. Just say that it is a crop at native resolution, or that it has
not been re-sampled. In fact why not only state what you have changed,
if I publish a picture I should not have to list all the alterations I
have not made.

Why not just think of the phrase as a name or technical
term instead of a descriptive one

Because we already have technical terms: 'original resolution', 'not
re-sampled', etc. The technical terms '100%' means the full amount or
all of it, a 'crop' is a part.

? There are plenty of
examples where what started out as an attempt to describe
something evolved (and often condensed) into something
that's rather meaningless by itself. For instance, we speak
of the DOF of a two-dimensional picture,

Do 'we'; DoF is a property of the three dimensional scene and how it
maps (translates for the non-mathematicians here) on to a two
dimensional picture.

and white balance
when there's not a single white spot.

Surely that refers to the image being corrected to look as it would when
illuminated by white light and not the blue or red skewed light that was
used perforce. It does not refer to any part of the image being white,
or even that the sum of all points in the image as being white.

The "spider" (inner
suspension) of a speaker has not resembled a spider in
appearance for the better part of a century.

That, perhaps, is a better simile, although I have not looked at the
construction of speakers in a long time...

--
Ian G8ILZ

On Thu, 13 Jul 2006 11:29:01 GMT, Roger Whitehead
wrote:

In article , John Bean wrote:
Somehow the whole term seems like an oxymoron. What is the crop 100% OF?

It's 100% of the pixel count - in other words the original
pixels, not a re-scaling of any sort.

So is it the same number of pixels as the original file or is it a smaller
number?

It's the same number of pixels there are in the crop. The
crop size is unimportant, but whatever pixels it contains
are exactly as they are in the original.

As I said - it simply means "not resized or scaled".

--
John Bean