An app to batch resize images on a mac?

Are you in photos or a folder on the mac

In photos - select all the images, then right click>edit with>preview

In a folder, again select them all with finder. Right click and open with preview.

Either way, you then have preview with all the images open (shown in the left hand panel). Select them all in the left hand panel before going to tools>adjust size.

Actually I figured it out. You have to have a preference in Preview selected for it to open all photos one PDF. I usually prefer to have each image in it's own file, but for batch processing, your idea is awesome.

Preview can do it.

Open all the images in preview (select them, right click, open in preview)

Select them in the left hand preview bar

Tools>adjust size

file>export selected images

Give this app a try: Resize Master. You can drop a folder of image files into its open window and resize them according to a number of options:

You can get it at the App Store.

You can also do it to some degree by exporting out of Photos with these options:

What do you mean by resize, exactly? That could refer to the dimensions of the image (length by breadth, in pixels) or the file size - MB or Kb?

When I do this, each photo opens separately in Preview. How do you get them to open all in the same file so you can batch process like you indicate?

Cool - I've learnt something. I didn't know about that preference.

Thanks.