# Cropping to 100 %



## mrgooch (Mar 22, 2014)

How can I tell when cropping a photo that I am at 100% and not degrade the image degrade?


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## Tony Jay (Mar 23, 2014)

Hi, I am a bit confused by your post and exactly what your question is, however, I will answer as best I can and we can fill in the gaps later if required.

Any edit in Lightroom, including cropping, is non-destructive and so can be reversed at any time.

In the Develop module it is easy to know if you are at 100% of image size because that is a 1:1 view.

I think your question really pertains to export/print quality but you will need to explain in more detail what your concerns are.

Tony Jay


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## mrgooch (Mar 23, 2014)

OK-So I am cropping a small portion of an image. If I crop it too small can I go over 100% ? If I can, how would I know the limit? I am going to print it.


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## clee01l (Mar 23, 2014)

100% of what?    When you crop, you crop a window of pixels.  Lets assume that your crop window is 100px X 100px.   if you look at the result with no zoom you will see 1 pixel of the image for every pixel on your monitor.  It will appear as a 100 square pixel box on your monitor You can zoom your monitor in or out. This will have nothing to do with the crop, it is still 100px X 100px.  Your Zoom may represent that 100 sq pixel image as a 200X200 pixel image or a 50X50 pixel image on the screen.  All that has done is translate the original pixels of the image into the new representation of the pixels on the monitor where the pitch of the monitor is fixed.  On a typical std definition monitor, the pitch is about 100 pixels per physical inch  So if you Zoom 2:1 the 100 sq pixel window will cover ~2 sq inches.  If you zoom the opposite direction (1:2) the 100 sq pixels will appear in a 1/2 square window.  You will notice that I have not used the word "percent" since it does not apply. 

Let's assume that you have a monitor that is 1920X1080 pixels.  If you want a crop to fit precisely inside that monitor, you want one image pixel to equal one monitor pixel (no translation).   So a crop od 1920X1080 would be the smallest that you could go and fill up the screen without causing the display program to translate more pixels on to the screen than the image had to begin with. 


Now, let's move on to printed images on paper.  A printer can typically print 300 pixels per inch  (ppi).  For an 8X10 inch image on paper you need to begin with an image that is 2400X3000 pixels to get the printer to not translate the pixels of the image into pixels printer by the printer.  Your crop window would need an aspect ratio of 4:5 (8X10),  and be that minimum size in pixels.   You don't have to have 300ppi to get an acceptable print.  Most people will say the 180ppi will do nicely.  So a crop of 1440X1800 pixels would still product a print of acceptable quality even though the 180 image pixels have been translated to 300 pixels for every inch printed.


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## mrgooch (Mar 23, 2014)

I understand your explanation. Now can you tell me what 1:1 is in view screen choice?


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## Jim Wilde (Mar 23, 2014)

1:1 mode simply means map one image pixel to one monitor pixel, i.e. there is no up or down sampling of the image to fit it into the display window, and as such it is the only recommended viewing choice in the Develop module when assessing sharpness/noise.


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## Replytoken (Mar 23, 2014)

If you want to crop to a specific size in pixels, i suggest using something like FastStone Image Viewer.  This will allow you to set the exact pixels for your crop, and show it to you in the process.  Perhaps this might help with your situation?

--Ken


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