Guidance required on description of Crop.

[martycon]

Thanks to the many who helped me to understand the meaning of a !00% crop. I find 1:1 a better description, but that is beside the point. I think that 100% is a very big crop, but for my guidance how would more experienced people describe a crop as big, medium, small etc, as a nominal percentage of 100%.
cheers marty.

[ameerat42]

Hmm Maybe they wouldn't, but who knows It's the
"Information Age", so expect to be both Informed and Mis-informed...

The thing is that "100% crop" has become a de-facto "technical" term.
>>>HOWEVER<<< it is still misapplied.

Basically, it means a crop of an image that has NOT been re-sized. But it does
cop (not crop) a bit of bandying about. If you think of "a crop of a full sized image"
I think that might help. It is NOT, BTW, JUST a crop of an image displayed at 100%.

Ie, it may be that, as long as it hasn't been re-sized.

(Better stop here...)

Back to your Q: I don't know ....

apart from suggestions like "half-size", three-quarter full size", etc...

[martycon]

Thanks Am, I am not surprised that your answer is not brief and simple, tho I hoped it may be. If I posted an image in AP, and described it as " cropped at 40% of full size before resizing", would that be sufficient and correct information? Just to complicate things, when you say half, would that have to be half the area, would it not?
regards marty.

[Hawthy]

Marty, websites that review cameras often show small crops of photos to display detail so that 'pixel-peepers' can gasp about the chromatic aberration or the shadow noise or the lost highlights or the innumerable other minor issues that people who are not addicted to photography would never notice. They often note these as being a 100% crop. I assume that this means that it is a crop of a photo as it is displayed in Photoshop (or other software) at 100%. Is this where you are getting the term from?

In my mind, a 1:1 crop is square. Both the horizontal and vertical edges are the same. A 16:9 crop is like a widescreen television. A 6:4 crop is what my DSLR produces by default - the same ratio as a 6 inch by 4 inch photo. So, a crop ratio is not about how much you cropped out but is about the ratio between the horizontal and vertical axes.

You can choose to crop or not to crop your photos as you see fit. You don't need to tell anyone whether or not it has been cropped. If you want to you can always say something like, "I had to crop out this really ugly bloke from the left edge of the photo, so I cropped about a quarter."

Hope that this helps.

[ameerat42]

...If I posted an image in AP, and described it as " cropped at 40% of full size before resizing", would that be sufficient and correct information? Just to complicate things, when you say half, would that have to be half the area, would it not?...

(To me) the first description is accurate to the extent that it does not say by how much the image was re-sized. The "cropped at 40%" would mean you show only 40% of the full image.
Fully, you'd have to add the likes of "resized to 20% (or 60%, or 200%) of original".

But if you just presented a bit of a 100% crop you would not have to say how much of the original image you left out/are displaying.
So, if you had an image that was 5000 pixels full size out of camera and you show us a crop 1000 pixels wide, that's good enough as long
as you just say it's a 100% crop. The actual size in inches/centimetres that it appears on different screens is irrelevant. However, if you
want to give more information, that's OK as well.

Now to "when you say half". To me, you would have to specify whether you meant half the "area", or half the "linear size". Generally, I would
assume the latter.

Basically, just give simple descriptions of what you're presenting. If you are uncomfortable with "here's a 100% crop...", say something else tha
means the same.

I hope this is not 100% confusing
Am.

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Marty, websites that review cameras often show small crops of photos to display detail so that 'pixel-peepers' can gasp about the chromatic aberration or the shadow noise or the lost highlights or the innumerable other minor issues that people who are not addicted to photography would never notice. They often note these as being a 100% crop. I assume that this means that it is a crop of a photo as it is displayed in Photoshop (or other software) at 100%. Is this where you are getting the term from?

Hawthy. No, this is not right. A 100% crop is just a crop of the full size image, no matter how it was displayed, AS LONG AS the image was not
resized or resampled. Ie, as long as you did not turn a 5000 pixel wide image into a 7000 pixel-wide image, or into a 3000 pixel-wide image, etc.

In my mind, a 1:1 crop is square. Both the horizontal and vertical edges are the same. A 16:9 crop is like a widescreen television. A 6:4 crop is what my DSLR produces by default - the same ratio as a 6 inch by 4 inch photo. So, a crop ratio is not about how much you cropped out but is about the ratio between the horizontal and vertical axes.

Yes. As long as you DIDN'T use the "1:1" term to mean something else, especially with the word "crop", this would be right.

You can choose to crop or not to crop your photos as you see fit. You don't need to tell anyone whether or not it has been cropped. If you want to you can always say something like, "I had to crop out this really ugly bloke from the left edge of the photo, so I cropped about a quarter."

Hope that this helps.

Yep, that's about right. Of course, the converse is implicit.

[Mark L]

"I cropped this heaps so ...... ."
"I cropped this a little bit."

[ameerat42]

But the point is that you mention any cropping when it is significant/germane to
the presentation (for CC).

[Hawthy]

Hawthy. No, this is not right. A 100% crop is just a crop of the full size image, no matter how it was displayed, AS LONG AS the image was not
resized or resampled. Ie, as long as you did not turn a 5000 pixel wide image into a 7000 pixel-wide image, or into a 3000 pixel-wide image, etc.

AM. Have a look at this and note the use of the term "100% Crop" : https://www.dpreview.com/reviews/nikond5100/17

I agree with you that a 100% crop is a crop (and on these websites usually a very tight crop) of the full-sized image. It is confusing for people because they think that a 50% crop means that they have cropped 50% of the image. Obviously, one can't crop 100% of the image and have anything left to display. I failed Social Maths (that is why I am working in finance) but I do remember the difference between a percentage and a ratio.

[ameerat42]

Hawthy. Thanks for the link. Before I look, may I hasten to add, and apologise somewhat, that I
should have said that it means "a crop at 100% size or the full size of the image". Now I will read the link...

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---A little time later...

OK, I had a look at what they're saying there. Yes. They are using the term correctly and they are showing the correct display.

Explanation:
I clicked on the very last image just before the heading "Shadow Noise". It's a picture of "a couple of masks", for want of better,
and beside that they have their labelled "100% crop" of part of that main picture. Note that you can click on the picture to open
it in a larger view, but you CAN'T click on the "100 crop" and open that..

Now, if you open the full image it almost fills you screen, but then click on it again since it shows you can enlarge it to its "FULL size".
Note that their "100% crop" now appears as the same size as part of the full image at maximum display size.

The point is that they did not change the size of the original image to get the crop.

Ie, no difference between what I'm saying (somewhere) above and what they're showing. - A crop of the FULL SIZE image.

[martycon]

Hawthy, thanks for your comments, they help. You are right, yes I refer to the 100% as in photoshop. What I am looking for is a generally accepted broad definition definition of what is meant by "a big crop" or "a small crop" etc. You have also introduced another form of crop, which could be called a "crop to format". My thought is that in order to describe and discuss cropping, (and indeed any subject), we need to be able to fully understand what the other is saying.
regards marty

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Mark, I would sometimes like to know whether your cropping "heaps" increased the viewed size of your bird to one and a half, twice, or even three times its presented length, compared to the uncropped image. Especially if your 3X image was tack sharp and I was looking for a similar lens.
regards marty.

[Mark L]

Mark, I would sometimes like to know whether your cropping "heaps" increased the viewed size of your bird to one and a half, twice, or even three times its presented length, compared to the uncropped image. Especially if your 3X image was tack sharp and I was looking for a similar lens.
regards marty.

Rather valid comment.
Have had others suggest posting the original photo then the crop to show what's going on. I could do this presenting one or two photos, but I like to present 4 or 5 photos in my threads.
Therefore I think your question is good. But are we all going to say "I cropped the first at ....... and the second wasn't cropped at all."
Think AM is getting at the point that we present photos how we present them and there needs to be a reason why you need to say it's a ......... crop. Sometimes "cropped heaps so it looses some detail but thought it was interesting enough to post" works.
"Mark. I'm thinking you missed a bit of detail in the chest. Is this because you cropped a lot?" Ask questions if you want answers.

It's getting late (for me) but will now head off and PP a small bird I took a photo of yesterday and post the original and the crop for you.

[martycon]

Thanks all for your interesting and helpful comments. I sort of thought that something like,"a 1.6x crop" might be a simple and informative statement, but no such comment seems possible.
The days of film were simpler, when most folk readily understood the meaning of "a 1.6x enlargement". I do not recall doing or seeing an enlargement of an enlargement, but if a 2x enlargement was enlarged 1.5x, then the result would just be a 3x enlargement. If I now use the term "1.6x enlargement", I think most folk would understand that the subject of interest will be 1.6 times longer and wider than it would otherwise be, regardless of what magnification was used to view it. So, how about enlargement as a non technical descriptor.
kind regards to all, marty

[ameerat42]

OK, so now you're talking about "enlarging/ments". .

Earlier you were talking about "crop/ping". I would call that the discarding of unwanted
parts of a scene.

An enlargement is not a crop. -- And, an enlargement does not always involve a crop.

Take a single image printed at two different sizes, say, 6 x 4 inch and 12 x 8 inch, but containing
exactly the same scene. There is NO cropping involved in that enlargement. You have NOT discarded
unwanted parts of a scene.

Best keep the two words "crop" and "enlargement" separate.

You can say "I, Martycon, enlarged the image of the bird 1.6 times using Photoshop to resample
the image AND THEN cropped away half/a third/a quarter of the original frame/cropped to 16x 9..."

It's hard to give an analog of enlarging a film negative in digital photography terms. "Re-sizing", such as in
Photoshop and the like, can be done just by re-defining the "pixels/inch" setting, OR by a whole resampling
of the original image.

The first will just display, say, a 15 MPx image larger, while the second will CHANGE the megapixel count of the image.

So, "enlargement" ≠ "crop".

[martycon]

Am, your para You can say "I, etc" is exactly what I wish to say, but fewer words. Also with slightly more information than the standard "big crop". Ok, so I will reluctantly adopt the obvious, and just use "big crop" which descriptor seems to be in common use. Small crops seldom need remark, and who but a statistician would understand medium.
regards, marty.