PART ONE: HOW IT WORKS
We all know what cropping does. It removes part of a photo. If we had a physical photographic print in our hands, we'd crop it by cutting it with scissors or a scalpel, and throwing part of it away. In digital terms, we remove some excess pixels from one or more sides of the file.
In all programs, the Crop Tool looks something like this:
Let's discuss cropping in various software ...
Cropping raw files
In Adobe Camera Raw and Lightroom (and probably all the other raw programs too), it's really simple. You have two options - crop to a specific rectangular ratio; or "freeform" crop to any rectangular shape you wish.
If you want to freeform crop (no specific shape), you don't need to do anything special. Just grab the Crop Tool, draw the crop marquee, press Enter, and the excess is removed:
Note: when cropping raw files, the excess detail is never actually deleted, it's just hidden. You can get it back at any time by choosing the Crop Tool again, then pressing the Esc key. This is consistent with the "non-destructive" nature of raw editing.)
If you want to crop to a specific shape, it's still very easy. You just need to choose one of the preset ratios which Adobe provide ...
... or choose "Custom" and enter your own desired ratio:
Once you've chosen your ratio, crop as usual. The unwanted pixels are removed (hidden), and the remaining ones are in the shape you chose.
When you draw your crop marquee, you can click in the middle and drag the whole thing around. Or, you can grab the handles at the corners to resize the target area. (If you're cropping to a specific ratio, you'll only have handles on the corners; but if you're freeform cropping, you'll have handles on each side as well.) When you hover your mouse just outside the handles, you see that you can rotate the crop; but be careful with this - make sure you don't do it accidentally!
Cropping in Photoshop
(Please note: when I refer to Photoshop, I'm talking about Elements as well.)
Photoshop is where most cropping happens, and it's slightly trickier to understand than in raw. That's because there are three options. As well as (1) freeform cropping, and (2) cropping to a specific ratio, there is also the option to (3) crop and resize at the same time.
Let's take a look. When you select the Crop Tool in Photoshop, you see the Options Bar has Height, Width and Resolution fields, like this:
If you want to freeform crop, leave all of those fields blank. Just draw the marquee, and crop:
As in raw, you can manipulate the crop marquee with its handles, and rotate it if desired. If you decide you don't want to crop after all, just press the Esc key.
The difference between raw cropping and Photoshop cropping is that Photoshop cropping is permanent. Once those pixels are discarded, they're discarded! So choose your crop wisely :)
That was easy. Now it gets more confusing ...
If you want to crop to a specific shape, you enter values in the Width and Height fields, but leave the Resolution field blank:
Ok, ok, obviously I'm pulling your leg with that last one :D Photoshop doesn't really recognise light years as a unit of measurement!
But I did it to make a very important point. It doesn't matter what unit of measurement you use for the height and the width. Inches, centimetres, picas, light years, nautical miles, 7-irons ... it's irrelevant. (The only one you can't use is pixels, for reasons I'll discuss later.)
As long as you keep the Resolution field blank, the unit of measurement can be ignored. All that matters are the numbers. In the first example, I'd be cropping a rectangular shape in which the height is one-and-a-half times greater than the width. In the second example, I'd be cropping square. And in the third example I'd be cropping a rectangle whose height is five-sevenths of its width. I am not imposing a particular size on my images at all - just a geometric ratio.
Needless to say, there are some common shapes in photography. DSLRs capture images at 2:3 shape. Compact cameras are usually 3:4 shape. 5x7" prints are 5:7 shape (duh!) and 8x10" prints are 4:5 shape. And so on. However, the only shape you'll ever really need is the 11:15 shape. That's the shape I recommend for proofing, and for providing digital files to customers. You can read about those important topics here and here.
One more thing. When you crop to a ratio, and leave the Resolution field blank as I described, Photoshop will adjust the resolution (PPI) of the image to whatever value it needs. This tends to freak people out. "Why is my resolution 486.291??? Shouldn't it be 300?" I assure you you can relax. In this method, the pixels per inch value is completely meaningless.
Cropping and resizing
Ok, now we move on to the last option - simultaneous cropping and resizing in Photoshop.
The two previous options shared one very significant characteristic - they removed unwanted pixels from the image, but left the remaining pixels unchanged in any way.
Option number 3 resamples the pixels while cropping, meaning that the portion of the photo which remains is either enlarged or reduced. It's most commonly used when saving images for print or web.
Here's an example of an image which has been cropped AND resized at the same time:
You can see how the surrounding unimportant detail has been trimmed away, and the good part has been shrunk down, ready for uploading to Facebook, or wherever.
To use this method, you need to have a specific purpose for cropping, and a specific size in mind. And you need to put values in all three of the fields - Width, Height and Resolution.
In this example, I'm ready to crop an 8x10 print at 300ppi:
If I crop an image with these settings, it will remove the excess pixels which I don't need, then resample the remaining pixels to exactly 8x10 inches at 300ppi. Then it's ready for me to sharpen, and send to my lab.
(Most labs suggest 300ppi for printing, but not all. Check your lab's website for specific advice. More information about resolution here.)
(8x10 prints tend to present particular problems to photographers - read this article for more information.)
The only time you don't need to include a value in the Resolution field is when cropping/resizing for web. Web images are always measured in pixels, and web browsers only read pixel dimensions - they completely ignore the resolution. You can put a value in that field if it makes you happy, but I assure you it makes zero difference. (And no, 72ppi is NOT web resolution.)
In this example, I'm ready to crop to 900px wide for uploading to a blog:
As you would have guessed by now, Photoshop recognises abbreviations for the units of measurement. The two you'll use most often are "in" for inches, and "px" for pixels. If you enter numbers by themselves, Photoshop will automatically assign whatever default unit of measurement you have set up in Preferences. Be wary of this - you could end up with a much smaller file than you anticipated. Always double-check the unit of measurement you're cropping with.
That's about all there is to tell you about the technical aspects of cropping.
PART TWO: CROPPING IN THE WORKFLOW
Now it's time to discuss when and how cropping should take place in your imaging workflow.
Let me make this very plain: DON'T CROP DURING EDITING.
Seriously. Don't crop your raw file, and don't crop in Photoshop while creating your masterpiece. Edit the whole photo.
I know what you're thinking ...
"But I need to crop away some dead space!" No.
"I have to crop to the Rule of Thirds!" No.
"Shouldn't I remove that ..." No.
"What about ..." No.
"But ..." NO.
Keep every pixel while you're editing.
You do NOT know when you're going to need those pixels. It costs you nothing to keep them, and it might cost you a heck of a lot of time if you don't.
The most common problem caused by early cropping relates to print sizes. If you crop to one particular shape, then your client (or your Mum, or whoever) orders a print of a different shape, you can find yourself in trouble.
You'll also find yourself in trouble if you've cropped tight, then your client orders a gallery-wrapped canvas. The tedium of trying to create extra detail around the edges of your photo to give you enough space for the wrap will drive you up the wall. With every mind-numbing stroke of the Clone Tool, you'll be thinking "Why didn't I just keep the pixels that were there in the first place??"
These problems occur equally whether you crop to a specific shape, or freeform crop. Either way, you're cropping without purpose, and I promise it will bite you before too long.
While I'm on this subject, I must also stress the importance of "shooting loose" in camera. Not really loose, but you should definitely allow 5-10% extra space around your ideal composition, just to be safe. Modern cameras have SO many millions of pixels that you can easily spare a few around the edges for peace of mind. The "Fill your frame" mantra is long-established, but it's unnecessarily dangerous, and I urge you to take a small step backwards.
I'm sure my message here is striking a chord with experienced photographers. Most have made the mistake at least once. In a recent discussion in our Facebook group, several people recounted their own experiences:
"I learned that lesson the hard way on my very first not-my-own-children session! My cousin's engagement photos - first she was going to make 16x20 and then she was going to get them printed square and then she changed back to some kind of rectangle. And every time I had to re-edit!"
Jill, Texas.
"I cropped a family photo and it looked fantastic. Until they wanted it on a canvas. It had been a lengthy edit so instead I spent ages 'creating' extra image at the edges. And it looked crappy so I ended up paying $60 for a wasted print and redoing it."
Kim, New Zealand.
"I have certainly learned that the advice "Fill your Frame" is NOT the best way usually! SO many people tell you to fill the frame with your subject, but that can cost you later. Gallery wraps can't be made from a filled frame shot... or not easily anyway."
Sandy, Alabama.
"I learned this the hard way on my very first client session - NEVER again!"I urge you, learn from the mistakes of others, not your own. If cropping is a habitual step in your editing workflow, remove it now. Keep all of your pixels.
Cyndi, Kentucky.
So, am I suggesting that you should never use the Crop Tool? Am I suggesting that you should display and print every pixel you capture?
Of course not. Cropping is composition, and composition is an integral part of photography. Your clients should only ever see photos that you've cropped perfectly.
But cropping must be part of the output process, not the editing process. Once you've edited and saved your whole image, that is your Master File, from which all cropped versions will be created.
For each output purpose, you open the Master File, and crop it. Then you perform any other output steps that might be necessary (eg resizing, sharpening, watermarking, vignetting, or profile conversion), then save as a separate file. Be extremely careful not to save over the Master File.
Needless to say, each of the output purposes in the above diagram require their own cropping method. Proofs are cropped to the 11:15 shape, and resized suitably for your proof site. Prints are cropped to the exact ordered size. Canvases are also cropped to the ordered size, with extra room for the wrap, of course. Images sold on disk are cropped to 11:15 without resizing, and images for your web portfolio can be cropped however you please.
Almost 100% of the time, the output files will be Jpegs. The Master File can be a PSD, a Tiff, or a Jpeg, depending on your needs. You can read more about the Master File workflow here.
I hope this tutorial has been useful for you. Please visit me at Ask Damien if I can help you with further information.