I am processing a few hundred product shots (shoes, sandals, boots). I'm working in Lightroom and Photoshop. The output will be 1200x1200 px JPEGs, pure white background (no shadows).
I want to size all the subjects so that they are 1000 px in their largest dimension. Can you tell me how to do that? Right now I am just eyeballing a crop until I think it looks like there are around 100 pixels on each side.
Presuming much larger originals, crop them so that you have the approx visual space on the longest edge. Next use the File > Automate > Fit Image command and enter 1000px into both fields. Next resize the canvas with white extension colour to 1200 x 1200 px.
All of this can be recorded into an action for use with the batch command.
Edit: Take a look at the following recent topic for more –
Edit 2: I forgot to mention that depending on the image content, the Select Subject and then Expand Selection commands can be used to automate the Image > Crop command in an action for auto cropping, before the Fit Image and Canvas Size steps.