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100% Crop: Explain it like I'm a 4 Year Old

Designer Dale

Designer Dale

macrumors 68040
Original poster
Mar 25, 2009
3,950
101
Folding space
Hi there friends and neighbors.

I see the term "100% crop" often on the forum, but I have trouble wrapping my tiny brain around it. To me, 100% is all of something and "crop" means cut off. So if I do a 100% crop of my little finger, then I have 0% little finger left. Ouch! This can't be right. If it means "This is 100% of the original", then it's full frame or uncropped. 0% crop.

Enlighten me and show me the way, oh most excellent brothers and sisters.

Dale
 
Basically, a 100% crop is where you are seeing, for example, 900x900 pixels of the image on 900x900 pixels of the screen. Cameras nowadays take pictures at a far larger resolution than our monitors can display like 3888x2592 (10MP from an image on my 40D).

Say I have a MacBook Pro with a monitor that has a resolution of 1440x900. To view a 100% crop of that image, I would have to zoom in to that image until I am viewing just 1440x900 of that image on the screen. So a pixel in the image would be represented by a pixel on the screen. In other words, I would have to view 13% of the total image to see a 100% crop. Hopefully that made some sense :eek:
 
Is this the same as hitting Command-0 in PhotoShop? A 1620x1050 desktop design blows up to 1620x1050 on my screen? I understand "working at 100%" in design, but not cropping a photo.

This is where I get lost. How does 13% in the above example become 100%? And since we all have different screen size and resolutions, isn't 100% crop different for each of us?

Dale
 
Literally, it means "A crop of an image displayed at 100% zoom".

If you are in Photoshop, and use the View > Actual Pixels... that's effectively 100% zoom and if you take a crop of that, you have a 100% crop :)

EDIT: @Dale... you got it. What's left over after the crop is still zoomed to 100% so it can keep the name 100% crop. The 100% refers to the zoom, not the portion of the image you kept. Of course, a 100% crop is only valid if you don't resize it! :)
 
Last edited:
I appreciate the question and answers.

So what you're saying is a 100% crop is n camera pixels displayed in n monitor pixels. What about a 50% crop? Is that 2xn pixels displayed in n monitor pixels? Or would that be 2x the height and 2x the width (meaning actually 4xn camera pixels displayed in n monitor pixels)?
 
DeG2 said:
I appreciate the question and answers.

So what you're saying is a 100% crop is n camera pixels displayed in n monitor pixels. What about a 50% crop? Is that 2xn pixels displayed in n monitor pixels? Or would that be 2x the height and 2x the width (meaning actually 4xn camera pixels displayed in n monitor pixels)?
Click to expand...

Technically you're correct, a 50% crop would presumably be a crop from an image at 50% zoom, but I've never come across anyone using the terminology in a generic way like that. It's either a 100% crop, or it doesn't matter. :)
 
Dale- seems like you got it now.

I am not sure I have seen the exact terms 50% crop, but I have seen 200% crop used before. Anyways, the principle is the same.

The usefulness of 100% crop, for example when evaluating sharpness, is that one can see the actual pixels in an image, without having to load or display the whole thing. If the corner performance of a lens is in question, a 100% crop of the corner is easier to show and compare than the full images viewed at 100%.
 
VirtualRain said:
Literally, it means "A crop of an image displayed at 100% zoom".

If you are in Photoshop, and use the View > Actual Pixels... that's effectively 100% zoom and if you take a crop of that, you have a 100% crop :)

EDIT: @Dale... you got it. What's left over after the crop is still zoomed to 100% so it can keep the name 100% crop. The 100% refers to the zoom, not the portion of the image you kept. Of course, a 100% crop is only valid if you don't resize it! :)
Click to expand...

Makes sense, I guess. According to the link below, my monitor has a DPI of 96. Would your 100% crop thing be physically smaller on it that on a 72 DPI screen?

Wouldn't "1-1 crop" be more correct? You are cropping an image that is 1 px - 1 px on the screen.

What's My DPI?

Dale
 
But the same 100% crop shown on 2 different monitors of differing DPI would still show the same detail level because it is still 1px for 1 image pixel

The term 100% comes from the zoom level of the picture, not the size of the physical representation on the screen.

Ruahrc
 
Ruahrc and VirtutalRain: Thanks for the explanations, I have it now. 100% crop is one of those terms that has been illusive to me. If I ever have to use this, I think I will go with "Cropped from 100%" instead. That is more literal for me.

Dale
 
I've been wondering this same thing since getting into these forums. Thanks Dale for being brave enough to ask the question. And thanks to everyone who answered. I now understand it. At least I think I do :p
 
Designer Dale said:
Makes sense, I guess. According to the link below, my monitor has a DPI of 96. Would your 100% crop thing be physically smaller on it that on a 72 DPI screen?

Wouldn't "1-1 crop" be more correct? You are cropping an image that is 1 px - 1 px on the screen.

What's My DPI?

Dale
Click to expand...

1:1 = 100% :cool:
 
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