Yes, there is a difference between cropping and resizing. Most people, even photographers, use those terms interchangeably, but they really have different meanings. So you may wind up with the situation where a photographer is using the term crop to mean one thing, but the client means something different when she uses the word crop. I’ll explain why they are commonly confused.
Cropping vs Resizing
Cropping is “cutting something out” of the photograph. You may be cutting out an unwanted object or you may be simply trimming a photo to get the composition you want.
Here, have an original photo of Cade, and the “crop overlay” which shows the part of the photo that will remain after it is cropped.
Nothing is cut from the photo when it is resized. It is simply made larger or smaller. Using the photo shown above, I have resized it from a native width of 400 pixels to a width of 200 pixels.
As you may have guessed, when you crop a photo, you will often resize it as well, which is why many people just use the term crop to refer to the crop and resize process.
Looking back at the resizing example, notice t’s the same photo, only smaller. Every part of the original photo is in the smaller one. Although it was resized, I kept the same aspect ratio. The aspect ratio is simply the ratio comparing the length and width of the photo (the ratio is usually expressed in its simplest terms Middle school math coming back to haunt you!). Both of the images in the resizing example have an aspect ratio of 2:3, which is the ratio of the sides of a frame of 35mm film. The ratio was kept when SLR cameras became digital SLRs.
Photographers tend to speak about aspect ratios where non-photographers tend to use physical dimensions. For all practical reasons, they are the same thing, although the physical dimensions of the photo may not be in the simplest terms. For example, 8×10 and a 16×20 photographs both have an aspect ratio of 4:5.
The Problem with Cropping & Resizing
Almost every photograph is cropped and resized before it is printed, although photographers really don’t like doing this. Why?
Filling the frame
Photographers are taught to get the composition right in the camera. In other words, shoot the photo correctly so it needs less work in post-production. This leads to a more efficient workflow. If you are a regular reader, you remember that one of the many rules (or suggestions) of composition is to fill the frame.
Printing photos in an aspect ratio different from 2:3, however, results in parts of the photo being cut off.
Here is a photo I made of a church’s congregation (before any post-processing was done).
When I made the photo, I wasn’t thinking about the church wanting a print of the photo. They wanted a 16×20, which is a 4:5 aspect ratio. The photo is in a 2:3 ratio. Here’s a preview of the photo if it was cropped and resized to fit a 4:5 ratio:
I had a problem. It appeared I would have to cut off some of the congregation if I cropped the photo. I chose a second option, and went back to the church and took a photo of the steeple and sky. This allowed me to composite those in, making a larger photo which game me room to crop to 4:5.
In this case, it worked out for the better since it was such a cloudy day when I took the photo. It gave me a much better sky in the finished product.
(I didn’t make that same mistake when I took the congregation’s photo this year).
I’m sure you have already guessed the solution to this problem. Shoot wide so you have room to crop.
This isn’t ideal because clients may sometimes reject an otherwise good photo because it’s hard for them to “see” the photo in a different aspect ratio. This is one reason I like to have a consultation with my clients before the photo shoot. It gives me an idea of what products they like and the sizes they would want.
With the megapixels that modern cameras can capture, you usually only run into this problem when you make an extreme crop and want to then enlarge the cropped image.
In this photo, I had to really crop in to fill the frame with my subject. I could probably enlarge the cropped photo to an 8×10 or an 8×12, but if I tried to enlarge it further, there wouldn’t be enough pixels to give an adequate resolution. As a result, the photo would look grainy, soft, and pixelated.
Photoshop and other specialized software has resizing algorithms, but these work much better in reducing the size than in enlarging. When you enlarge a cropped image, you have to make pixels to fill in the difference. Software can “guess” what shoud be there, but it’s not great and doing this. It is much easier to take pixels away while shrinking an image.
Proper planning can reduce many of the headaches caused by cropping and resizing. If I know my client wants a 20×24 canvas, I can plan to shoot photos in a certain way that best fit that aspect ratio. That’s why the consultation meeting is so important.