Crop to Widest Dimension of Selection

Sometimes, despite the obvious efficiency of scripts and plug-ins, there is satisfaction of solving a problem using only Photoshop regular tools . Here is one such solution, doing the work on a duplicate of the original file.

1. Cmd+J to place the selected element on a separate layer

2. Choose both layers. Choose the Move tool. Options bar: Align vertical centers followed by Align horizontal centers. Un-choose both layers. Choose Layer 1 and dupe it. Turn off the Background layer.

3. Choose Layer 1 Copy. Edit > Transform > Rotate 90 Degrees

4. Choose Layer 1 and Layer 1 Copy. Image > Trim …Transparent pixels. Then un-choose the layers, choose Layer 1 Copy and drag it to the trash.

In my crafting action package I include a Plug-in script I wrote for making aspect Ratio selections or paths that are rectangular or oval.  The Plug-in records the Aspect Ratio you set in the action step dialog when you record the action step. No dialog is displayed when your action plays. Its like scripted  marguee and path tool. The selection is set respective to the Image orientation the selection will have the image's orientation or be square or round.  The Aspect Ratio is not a width height thing it is a ratio. the Script take into account the image orientation and set the best selection for the image.  For portraits do not crop well to a landscape orientation and landscaped do not crop to portrait orientation well too much content would be cropped off the resulting composition will not be acceptable in general.

A two step action will do  or you can do the two steps in Photoshop UI.

Automate Aspect Ratio Selection

Image Crop

Crafting Actions Package UPDATED Aug 10, 2014 Added Conditional Action steps to Action Palette Tips.
Contains

• Action Actions Palette Tips.txt
• Action Creation Guidelines.txt
• Action Dealing with Image Size.txt
• Action Enhanced via Scripted Photoshop Functions.txt
• CraftedActions.atn Sample Action set includes an example Watermarking action
• Sample Actions.txt Photoshop CraftedActions set saved as a text file.
• More then a dozen Scripts for use in actions

Example
Download

I would recommend a Scripting approach.

Photoshop Scripting

An image have one width.  A square crop is a 1:1 aspect ratio selection. Portraits aspect ratio image can be crop square to its width dimension with a 1:1 aspect ratio selection.. Which crop would you want. Landscape Images  can not be cropped square to their width size.  A 1:1 Aspect selection the width of a Landscape image would exceed the image's canvas size.

You can make a 1:1 aspect ratio selection in an image in either orientation.  The max size for a portrait would be a 1:1 selection the is the width of the image and the max size in a landscape would be the height of the landscape.  The selected area can me anywhere in the image canvas.