CO

Those terms would be better descriptions.

BigDaddy Loc: Pittsburgh, PA

I've used a lot of different editors, including PS, PSE, ACDSee, Affinity Photo, IFranview, and more. My favorite app for resizing, cropping and changing canvas size is none other than the absolutely free app FastStone viewer.
All these apps do it with various levels of ease, but FastStone has the best user interface I think. I crop/resize all my pictures for desktop, TV, Facebook Portal, UHH and occasionally prints. I like it so much I actually sent FastStone a donation for doing such a bang up job on his free viewer/editor.

For example, for a photo to UHH, which I generally want to send at 1200x800, a 3x2 aspect ratio. I load it in FastStone, full screen, crop it to 3x2 (X key). This will show the largest possible selection for the given image. If the image is already at that aspect ratio, it will be the full picture. If not, then move the crop around to select the best possible crop. Then resize (Ctrl R), enter 1200 for the long size and poof, the correct size is given. If the crop is not appropriate for the picture, say parts being cut out I want to stay, then close the crop, open canvas size and add a bunch of pixels to the canvas. I generally do 200 pixels all around, then crop again, leaving black space, or what ever color you want around the pic, and crop again. Yes, you can do this with any editor, and I have, but FS seems to be a step above, amazing for a free app. Also it does a lot of light duty editing, such as straightening, curves, color adjustments and so on. Give it a try it, costs you nothing. BTW, I used FS a good while before I knew it did all this so easily.

JFCoupe Loc: Kent, Washington

Adding to the OP: In Lightroom if I click on the 1:1 in the upper left corner of the screen am I then seeing a 100% crop of a section of the image?

Thanks for you ongoing information.

CHG_CANON Loc: the Windy City

Yes, although the 100% crop is loose language from a technical standpoint, the 1:1 zoom is synonymous with the concept of a 100% crop. You see the exact pixel resolution of the digital image as matches to the pixel resolution of your monitor.

Jerry Coupe Loc: Kent, WA

Okay, thanks for the confirmation on this.

cahale Loc: San Angelo, TX

Literally, cropping 100% is like eating 100% of the apple. You have nothing left. Another time when words don't mean what you think they do.

dleebrick Loc: Indian Land, South Carolina

This may be part of the answer. Let's say that the 100% crop displays a part of the original image that has as many pixels as your monitor does, in other words, 1164 by 776. Now, what portion of the original image, when cropped by 75%, would just fit in your monitor? The answer if 1552 x 1034, very close to your 75% crop values. What part of the original image, after cropping 50%, would just fit in your monitor? Answer is 2328 x 1552.
Unfortunately, this rationale doesn't work for the crops larger than 100%, so I can't explain that. But maybe this is part of the answer, anyway.

CamB Loc: Juneau, Alaska

No, this is just shrinking or enlarging the image on your monitor. It has nothing to do with cropping. If you crop you are cutting something away, not just viewing a larger or smaller part of the image (%) on the monitor. Two different things. The terminology gets confusing so sometimes posters ask the wrong question and everyone gets confused.
...Cam

R.G. Loc: Scotland

I think it's been established that the "100% crop" of the thread's title refers to viewing some or all of the image at 100% - i.e. 1:1.

CamB Loc: Juneau, Alaska

I agree. It's too bad that the word crop comes up on UHH repeatedly when talking about a photo that, in fact, isn't cropped. It leads to the confusion that has pervaded this thread. But you are right about its general acceptance.
...Cam

CO

The topic of this thread is 100% crop. What I described is correct. There is no actual cropping of the image. The software is mapping one image pixel to one monitor pixel. The software program needs to "know" what the screen resolution on the monitor is for this to be displayed correctly.

redrocktom Loc: Sedona

Great discussion article. Thanks

aellman Loc: Boston MA

Maybe I'm taking this too literally, but "100% crop" seems like there would be nothing left. >Alan

CamB Loc: Juneau, Alaska

You're right of course, but this whole thread ended up being about the different ways people use the term crop. Some see a crop as changing the composition by cutting away parts of the picture. Others call it a crop when you enlarge it on your screen so you are only seeing part of the picture. If you enlarge the file to 200% so that you are only seeing part of it, it looks like a crop, but it's really it's just pixel peeping.
If you were to actually crop it to just what you see (by cutting pixels), the final picture would, of course, be less than 100% of the original. Just to make it a little more confusing, you could then enlarge the cropped file to 200% on the screen, but again, it only looks like a crop when it's actually just a part of the existing file. And on and on.
...Cam

CO

The terminology is not good. Photoshop call the exact same thing "Actual Pixels".