# What exactly is a 100% crop?



## drmikeinpdx (Apr 27, 2013)

For years I've seen people post examples of a "100% crop" to show the sharpness of a lens or the noise level of a sensor. Today I was thinking about posting some images from a EF 70-300 f/4-5.6 IS that I just picked up and realized that I don't know how to do a 100% crop. Can someone provide brief instructions on how to do that? I'm using Lightroom 4 if it matters.


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## AlanF (Apr 28, 2013)

Nothing complicated at all. Just crop the area you want to upload and don't change the number of pixels in it.


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## ksagomonyants (Apr 28, 2013)

Let's say your image is 3000 x 2400 pixels. You crop a subject on this photo which has a size of 1000 x 800 pixels. So if you want to have a 100% crop, you'd have to bring the size of the cropped image to that of the original one.


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## privatebydesign (Apr 28, 2013)

Dr Mike,

I feel for you, despite the others posts Lightroom does not natively allow 100% crops, it can't do it. You can crop and then specify output dimensions on Export, but that is not the same thing.

In Photoshop and many other programs, in the Crop Tool you can not only select a custom aspect ratio, you can select pixel numbers, with that option you just specify 400px x 700px etc and click on the image, then a moveable box that size flashes, move it to where you want, click and the 100% crop is done.


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## drmikeinpdx (Apr 28, 2013)

Hmmm...

I can certainly use Photoshop to crop to a certain pixel size. I think even Lightroom will do that in the export options. However, that doesn't really create a standardized crop that folks on forums like this can use to compare lens resolution and such. To do so, I think we'd all have to agree that our sample images would be a certain standard portion of the original frame. Am I missing something?


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## privatebydesign (Apr 28, 2013)

You cannot do 100% crops in Lightrrom, you can choose an aspect ratio and crop any area of your image, but you don't know how many pixels that is, on Export, Lightroom will re-sample to whatever you specify.

So taking one step back, 100% crop means on your monitor at native resolution one image pixel is showing on one monitor pixel. So different screen resolutions will show that 100% crop at different physical sizes, with some Retina displays the graphics chip will re-sample the image anyway!

So, if you have a 5D mkIII you have 5760px x 3840px, the forum takes 700px long edge images inline. So if you want a 100% crop you need to specify a 700px x 700px crop as in PS or a similar program, not a 1:1 crop and then exported at 700px as in Lightroom.

100% crops are relevant if you realise everybody will see them at a different size, it is showing the pixel level detail of your images, regardless of the viewers screen.


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## RGF (Apr 28, 2013)

Drop the term crop - very confusing. 100% means not resized and soon at 100% resolution.

The term crop is used to denote that the image has been cropped so that number of pixels in each direction is the same as the size when displayed.

As other have said, not doable (at least easily doable) in lightroom if you goal is to get an image of a certain size (i.e, 1000 x 600 pixels)


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## weixing (Apr 28, 2013)

Hi,
Basically, 100% crop mean not resizing or 1:1. Lightroom will always export 100% crop image as long as you don't set the "Image Sizing" (Resize to Fit) during export. Also, to view 100% crop, you need to set 100% or 1:1 for your viewer software.

By the way, some website will resize the image automatically if it exceed a certain resolution when you post them, so make sure you know the maximum resolution that they allow and limit your photo resolution to that.

Have a nice day.


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## yablonsky (Apr 28, 2013)

100% crop means, that one pixel of the image is displayed by one pixel of your screen. That means no resizing of an kind. If your LCD has a resolution of 1920 by 1200 pixels, a 100% crop means you cut out a rectangular area of 1920 by 1200 pixels from your original image with any editing software.


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## AlanF (Apr 28, 2013)

yablonsky said:


> 100% crop means, that one pixel of the image is displayed by one pixel of your screen. That means no resizing of an kind. If your LCD has a resolution of 1920 by 1200 pixels, a 100% crop means you cut out a rectangular area of 1920 by 1200 pixels from your original image with any editing software.



No. A 100% crop should be independent of your own screen resolution or any screen resolution - it will be used by others on their monitors that may well have different resolutions. Your screen or software etc may not be able to show it all at once or might resize it, but that does not affect the definition of a 100% crop - A 100% crop is just a section that has been taken from the original image and has not been enlarged or reduced in pixel size from what is was in that original.


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## TommyLee (Apr 28, 2013)

drmikeinpdx

100% crop is like said here a few ways...
clip out a part of the full-sized shot...and dont resize it..

I use Faststone (a FREE photo utility you SHOULD have) for this stuff.. works great ...and on a series of photos keeps the same size you choose... for each consecutive pic...
in the 'Crop Board' use 'lossless crop to file' 
you can set the size of the crop sample.....
the word *sample *is a hint....
... it automatically appends _cr to your native shot

so here is a recent Smith River Panorama ...with a 300x200 100% crop

hope that helps

TOM

I use Faststone to look over my RAW CF card sometimes... it CAN convert directly to jpg .. in a pinch...
it is VERY useful.....


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## PavelR (Apr 28, 2013)

TommyLee said:


> drmikeinpdx
> 
> 100% crop is like said here a few ways...
> clip out a part of the full-sized shot...and dont resize it..
> ...


+1


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## nvsravank (Apr 28, 2013)

I use Lightroom and all my photos are 100% crops.
I don't allow Lightroom to resize my photos on export.

When you want to post to forums a 100% crop, what you need to do is to find the maximum pixel width and height that the site will accept and then in Lightroom use the crop tool to select a small area that fits within those dimensions. For most sites where the max width is 800 pixels it means you cannot post a 100% crop of the full picture but a small area is what you can post. So pick your area of the phot carefully to illustrate the issue you are having. 
Then export out of Lightroom with resize turned off. Lok at the final picture to figure out the final size that came out.


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## privatebydesign (Apr 28, 2013)

nvsravank said:


> I use Lightroom and all my photos are 100% crops.
> I don't allow Lightroom to resize my photos on export.
> 
> When you want to post to forums a 100% crop, what you need to do is to find the maximum pixel width and height that the site will accept and then in Lightroom use the crop tool to select a small area that fits within those dimensions. For most sites where the max width is 800 pixels it means you cannot post a 100% crop of the full picture but a small area is what you can post. So pick your area of the phot carefully to illustrate the issue you are having.
> Then export out of Lightroom with resize turned off. Lok at the final picture to figure out the final size that came out.



IF you want a specific number of pixels as an unresized 100% crop from Lightroom you can't do it without a lot of trial and error and guesswork. You can get an arbitrary 100% crop easily, just crop. But the control most people want when talking about a 100% crop is not available in Lightroom.


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## elflord (Apr 28, 2013)

drmikeinpdx said:


> For years I've seen people post examples of a "100% crop" to show the sharpness of a lens or the noise level of a sensor. Today I was thinking about posting some images from a EF 70-300 f/4-5.6 IS that I just picked up and realized that I don't know how to do a 100% crop. Can someone provide brief instructions on how to do that? I'm using Lightroom 4 if it matters.



It really is quite confusing because of the issues that come up when you try to display the image on the web. 

The 100% crop itself just means some cropped of the image that is not rescaled in any way. So for a 4000x3000 original, a "100% crop" of the top left quarter of the image would be 2000x1500. 

Generally, at this point, you don't have a problem -- if you ask your software package to "crop", it will typically do a "100% crop" for you -- that is, it will crop and NOT "crop and rescale" (why should it ? The latter is not something the user asked for!) 

Another place an image can get rescaled is in the web browser. In html, the IMG tag specifies an image width and height for display which do not necessarily need to be the same as the original image dimensions. 

Another place the image can be rescaled arises when you are uploading an image to a forum or any kind of website that displays pictures. In this case, the software on the server may rescale. If you are uploading an image that is larger than a typical screen resolution (e.g. more than about 2 megapixels), the image will not fit on a screen unless it is rescaled. So if you upload your original image and then the uploaded image fits on your screen, you can assume the server has rescaled it. The way to prevent the server from rescaling it is usually to crop out a small enough region image (e.g. 400x400) that any reasonable forum would allow it to be displayed at full size. In some cases, the server simply might not allow a very large image to be uploaded in which case you need to make the choice between cropping and rescaling the original. If your intent is to show a 100% crop, the choice is clear.


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## drmikeinpdx (Apr 29, 2013)

I guess I had the wrong idea about the 100% crop images people post on forums. I thought that it meant they were cropping the image to a certain standard percentage of the frame to allow meaningful comparisons with other images. 

Since it apparently refers to a 1 to 1 display of pixels on my monitor, it does not seem like a very useful concept for use on the forum. I like the way that the river photos were posted above. You can see the full image, then the small cropped section. That seems like a pretty practical way to show people how sharp your cool new lens is.


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## wickidwombat (Apr 29, 2013)

the easiest way to do it is to click 1:1 in lightroom do a print screen, crop that image out and then you can post that in the forum with the resized full image.
thats how i do it here anyway and it works ok


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