All Rectangles Are Not The Same (or even Similar)

Last updated on July 23rd, 2019 at 04:52 pm

Our friend, Ibis Hillencamp (whom you may remember for the advice she gave on our FAQ page about becoming a better photographerlink) thought people might need an explanation of a photograph’s aspect ratio and why you need to consider it when enlarging or cropping your images.

When you enlarge a picture, unless you want distortion, you have to increase the width the exact same ratio as the height. For example, a 4″ by 6″ image might be enlarged into an 8″ by 12″ image, or a 10″ by 15″, and so forth. For each of these examples, the aspect ratio, which is the height divided by the width (or vice versa, as long as you are consistent), remains the same (\frac{4}{6} = \frac{8}{12} = \frac{10}{15} = 0.66667  ). Mathematicians would call the three rectangles in this example, and all others with the same aspect ratio, “similar”. When placed at the right distances, you would not be able to tell them apart. SLR cameras, starting with the analog 35mm and continuing to the digital versions, have an aspect ratio of 2:3 and can make prints the size of any of the above examples with no problem. Other cameras have different aspect ratios. If you haven’t already done so, learn your camera’s aspect ratio.

And Now The Bad News

The problem starts when you try to put your picture in a standard-sized frame. They routinely have a different aspect ratio. If you want an 8″ by 10″ print, for example, you will be changing the aspect ratio to 0.8. An 11″ by 14″ print has an aspect ratio of 0.786. The simple answer would be to crop your original image, which means you are going to lose part of the picture. That could be a problem. The other option is to fill in any missing parts. That is almost always a problem. Let me show you.

Cropping options with a different aspect ratio
Nancy in an image with a 3:4 aspect ratio and a couple possible ‘crops’ with a 2:3 aspect ratio.

For those of you who do not recognize her, the above picture is of my wife, Nancy, the nature and wildlife photographer (No, this is not a selfie). This image has an aspect ratio of 4:3. Suppose we want to put her picture in a mat with a 3:2 aspect ratio. The easiest thing would be to crop to the red rectangle, which is the largest such rectangle we can get from the given material. But as you can see, there is no breathing space around the hat. So we could enlarge to the orange rectangle to use the original picture’s entire width, but we will need to get creative and fill in some along the top and bottom edges (by the way, can you guess why the top and bottom voids created by the orange rectangle are not the same size?). While the techniques to fill those voids are beyond the scope of this article, I would like to share a few thoughts. These thoughts apply not only to the case where you need to add material to change aspect ratio but for other causes also, like when you inadvertently cut off some body part.

Suggestions

  • The first moral to this dilemma is don’t get too tight on your subject while shooting. Start leaving yourself a little more edge room when you take your pictures. Besides not inadvertently cutting off body parts, which are harder to bring back after-the-fact, you might actually capture the subject’s whole reflection, which you didn’t even notice in the excitement of getting this unique subject.
  • The first step in processing this change in aspect ratio is to go back and check the original file. Maybe you had previously cropped the image for compositional purposes and the original might still have at least part of the now-missing material that you need.
  • Small, uncomplicated additions are easy enough with Photoshop’s Clone Stamp tool (and although I’m not a huge fan, sometimes Content-Aware Fill might even work), but it gets trickier as the size of the addition increases. It would be no problem to fill the new space above Nancy’s head with sky, and maybe even throw in an extra cloud or two, but if for some reason, we had wanted to extend the left edge of this image an inch or so, finding enough water to fill the gap without people noticing repetitions could be an issue.
  • Sometimes you can create more usable material from within the image itself by copying some of the waves, for example, and flipping them, or rotating them, etc. But you will have to judge the effectiveness of these actions on a case-by-case basis.
  • Look at the photograph you took just before this one and just after this one for more material. Especially if you are shooting wildlife, I know you had your camera on rapid-shoot. The neighboring shot that you didn’t select for this image may have ‘new’ material that would be useful for your current extension project.
  • Continue to expand your search area. Even if you didn’t get another picture of your subject squirrel that day, you might have other squirrel pictures you can use to replace that missing body part.

Send Your Ideas

Well, that’s all I have for now. Although I have no intentions yet of following this article with more detailed information on the Clone Stamp or other tools, I am pretty sure there are plenty of tutorials out there, both by Adobe and by several third parties. If you do have your own hard-earned techniques or suggestions on any of the material I’ve just discussed or even a horror story that’s relevant, I’m sure my readers would love to see your comments below. Thanks.

Thoughts On Mat Layout

The easiest and most common mat layout is one with the widths of all four borders equal. If you are forcing a picture into a standard-sized frame, however, that’s not always possible. And then there’s the matter of bottom-weighted mats.

Bottom-Weighted Mats

Bottom-weighted mats, or mats with the bottom edge wider than the others, were introduced long, long ago. Some say that pictures centuries ago were hung very high on the wall and the bottom width of the mat was increased to compensate for the ‘distortion’ of that perspective. Unfortunately, that story makes no sense; top-weighting would be required to correct for the top being further from the viewer than the bottom. Another explanation involves the notion of a difference between the visual or optical center and the geometric center. Yet others claim it is to compensate for the drop of the mat in the frame due to tolerances necessary to account for expansion, etc. For whatever reason, bottom weighting could be seen as an attempt to fool your audience or overcome optical perceptions, whichever you prefer. As commonly practiced in “finer frame shops everywhere”, the bottom width is generally increased ¼” to 1″, depending on the size of the pictureref.

Using Standard Mats

But how would one incorporate bottom weighting while fitting an image into a standard-sized mat? For example, if the vertical difference between the hole size and mat size is greater than the horizontal difference, and assuming the left and right borders will be the same width, is it better to:

 
 AMake the top and bottom borders equal,
 BMake the top the same size as the left and the right and put all of the extra width on the bottom,
 CMake the bottom larger than the top by some fixed amount,
DMake the differences even more subtle by making the difference between the top border and the side borders the same as the difference between the top and bottom borders?

Let’s clarify your choices with an example. Suppose you want a 4″-high hole that’s 7″ wide in a standard 8″-high by 10″ mat. The horizontal difference between the mat size and the hole size is 10″ – 7″ = 3″, so if you want the left and right borders to be the same, each will be 3″ ÷ 2 = 1½”. The vertical difference between mat and hole size is 8″ – 4″ = 4″.

Choice AWould make the top and bottom borders the same, making them each 4″ ÷ 2 = 2″.
 
Choice BWould make the top 1½” like the left and right borders, leaving 4″ – 1½” = 2½” for the bottom border.
 
Choice CUses the customary bottom weighting, which the one reference I give above lists as ¼” for an 8″x10″ mat (personally, a ¼” bottom weight isn’t worth the trouble). That means the top border would be (4″ – ¼”) ÷ 2 = 1⅞” and the bottom would be ¼” more, or 2⅛” (notice as you check your work that 1⅞” + 2⅛” = 4″). Finally,
 
Choice DIs a tad more complicated. Let’s call the difference between the left or right border width and the top border width “d”, such that
 1½” + d = T (for top border width).

Then the bottom border (B) would be

T + d or (substituting the last expression for T)
(1½” + d) + d = 1½” + 2⋅d.

Since T + B = 4″, then (substituting for T and B)

(1½” + d) + (1½” + 2⋅d) = 4″, meaning
3″ + 3⋅d = 4″ or 3⋅d = 1″, meaning d = ⅓”,

so (substituting back into our equations for T and B)

T = 1½” + ⅓” = 15/6” and
B =15/6” + ⅓” = 21/6

(again noting that 15/6” + 21/6” = 4″) .
Mat Weights
Our Four Mat Choices (drawn to scale)

The choice you make would be an artistic decision, but I think A is the most common answer. Choice C could be used for traditional bottom-weighting, as in our example, or could be used for some other more artistic value. Technically, both Choices B and D are possible results of that equation. B would be exactly what you get when you want bottom-weighting and are not restricted to standard mats; it would work best if the resulting difference between the top and bottom borders is not too much greater than the customary bottom-weighting distances mentioned above. In our example, it yields 2½” for the bottom border, which is an inch larger than the other three borders and may just be too much.  In our example, C and D are very close, and remain close when we change the amount of weight in C from ¼” to ½” (as shown by the lighter blue opening).  D is more subtle than C, but may only be worth the effort when the difference between the left and top borders is small enough to fool somebody.  In other cases with different numbers, results may vary. 

With Larger Side Borders

If the horizontal difference between the hole size and the mat size is greater than the vertical difference, you could face up to the same number of choices as above, but you are working with less material for the top and bottom borders and I think it is usually better to keep things simple and make those borders equal.

Differing Left And Right Borders?

Do the vertical borders always need be the same size? Although I can’t say I’ve ever seen or read about different-sized side borders, I’m not convinced that uniformity is strictly required. For example, in photography, as in older art forms, there a “rule” of spaceref that says, among other things, that there should be plenty of space on the side of the subject into which it is looking. If you have a “perfectly” centered and close-cropped picture of your mother looking to your left, could a mat with a wider border on the left side create the space that’s lacking in the image?  Maybe you could even choose a mat color that is a pastel version of the background to her right (your left)? Maybe a contrasting outer mat could be added with traditional (identical) vertical borders.

 I present the above thoughts to give some background and (more importantly) stimulate your own creativity. If you think of other possibilities, I’d be thrilled to have you add them to the comments. Thank you!