Tip #1587 - Keepin' it Proportional
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WorldStart
Have you
ever noticed when you resize a photo, there's usually an option to "constrain
proportions"? When you uncheck that option, you can plop in any height
and width dimensions you please. With constrain proportions checked, changing
one dimension changes the other. So what's with all the proportion constraining?
Read on.
Although
the term Constrain Proportions sounds like something used in a medieval
torture chamber, it's actually pretty simple.
When you
shoot an image with your digital camera, it's taken within the aspect ratio
of that camera (usually 4:3 or 3:2). For instance, my camera shoots an image
that's 3504 x 2336 - a rectangle that's fairly proportional to a 35mm negative
(a 3:2 aspect ratio).
Now, when
I go to resize this, I need to keep the image "proportional" or it'll
look distorted. When I take pixels away from one dimension (say the width),
I need to take a proportional amount away from the other dimension
(the height). If I don't it will look elongated or squished, depending on how
I change the width and height numbers. Constrain Proportions does this automatically.
This is
easier to demonstrate with an example:
Here's the
original photo. I've reduced it for the newsletter and kept the "Constrain
Proportions" checkbox checked:
This time,
I unchecked the box and just put in a pixel size of 400 x 400. Photoshop interpolated
and squished the image into this (yuck-ola):
Now, if
you find that you need, say a 5x7, but when you resize the image with "Constrain
Proportions" selected, you get something like 5 x 7.5, you'll know it's
because the aspect ratio of a 5x7 doesn't match your image ratio. Not to worry
though, Steve to the rescue :-)
All you
need to do is a little cropping to make the photo proportional. In this case,
crop off the top and bottom of the 5x7 (assuming a vertical photo, otherwise
it'd be a 7x5 and you'd hack a little off the sides).
If you're
trying an 8x10, you'll find you may need to crop even more in order for it to
work. Again, off the top and bottom if the photo is vertical, from the sides
if it's a horizontal shot (10x8).
As you go,
crop just a little at a time. Try the resize and see if you're close (within
like 5% or so). If you're not, cancel each resize until you are. Don't actually
do the resize until you see that you have the proper proportions. It doesn't
have to be 100% perfect, but get it as close as you can. Also, always keep a
copy of your original uncropped photo, just in case you want to make a different
sized photo with different proportions down the road.
As an example
of all this, let's say I wanted the sample image to really be a square that's
400 x 400. Here is the image after a correct crop (I cropped in a little too):
No distortion
:-)
What do
you do if you have a photo you just can't crop? Don't print it :-)
Or...
The first
option is to allow it to print at the "strange" size. If it wants
to be a 5 x 7.5, who are we to argue? If you're having it custom framed, it
doesn't really matter what size it is.
If you can't
crop it and you have to have a standard size, there's still hope (at least for
users who are a little more advanced). You can create an image with just a black
background that's proportional to the size you want (like 5x7). Make sure it
is at the same resolution as your original.
Next, resize
the original so that the height is 7 inches. This will make the width 4.6 (ish).
Now, drop
the photo onto the black background you created. Center it up and you'll have
a 5x7 with a black strip down either side, but at least it is proportional and
will fit into a standard frame.
Here is
our sample photo proportional to 7x5. No cropping of the image, but you have
to live with the borders:
Of course,
if you prefer a white background, you can do that too. Just set the height to
7 inches, let the width go to 4.6 inches, and print. Now, cut the image down
to 5x7, leaving a white border on either side.
There you
have it—more than you ever wanted to know about constraining proportions
and working with aspect ratios :-)
Happy shooting!
~ Steve
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