Is there a way to add padding to the automated crop and straighten photos?

It still seems like you might not understand that since Crop and Straighen Photos can’t do this by itself, we’re suggesting it is possible if you simply combine multiple Photoshop features.

I decided to try Melissa’s suggestion because I thought she was on the right track. The action shown below will do what you want for one of the images resulting from Crop and Straighten Photos:

Here is what it does:

Canvas Size — Choose the Image > Canvas Size command.

With Relative — Use the Relative option so you can enter the difference you want in the canvas size, like 20 pixels. With the Relative option, it doesn’t matter if the originals are different sizes; they will all get the same sized border added to them.

Width and Height — Enter 20 pixels for both, so 20 pixels are added to both Width and Height dimensions.

Horizontal: center and Vertical: center — Add the new pixels from the center, for both dimensions.

Extension Color: background color — The color of the extended canvas will be the current background color, such as white. It would be safer to add another Action step at the beginning that makes sure the background color is set to white.

The result of that is 10 extra pixels of white border added around the current image, such as one of the images separated out by Crop and Straighten Photos. The reason it’s 10 pixels is that the 20 pixels is across the entire width or height, so half (10 pixels) gets added on each side. If you wanted 20 pixels added along both dimensions, specify 40 pixels for each dimension.

Select Next Document — This step is because Crop and Straighten Photos produces multiple untitled image windows, so you want to run this action on each of the new documents. This last step makes sure that after it finishes adding a white border around one document, it switches to the next document for you.

You might also want to add a Save As step between those two, which could set the file format and folder to save them into. But you might have to manually give each new image an appropriate name.

The last step you requested is Crop, but it’s not clear why that’s needed. There will be no unneeded extra area to crop. Because you’re working with documents already separated out by Crop and Straighten Photos, each is already cropped down to the image edge with a border added, and nothing outside that.

This is where we reach the limits of actions. You do have to manually run this for every new document created by Crop and Straighten Photos, and when you are done you still have to manually name and save all of the new documents, and finally close the original document that had multiple scans on it. This is where scripting could make this better. A script might be able to count how many open documents there are, save each one with your naming convention and then close each, then when there is only one left open (the original scan with multiple images that you no longer need to keep), close it without saving. Unfortunately I’m not good at scripting, but JJMack is extremely good at it.

I'm with Melissa, do the crop as desired, then just make an Action to extend the canvas by X number of pixels or percentages etc. Be sure to set the bkgnd color as desired.

Once you have the action, you can then run a batch on a folder of cropped images.