How? I don’t see any way to set up a batch process to do what he wants.
Open all the images in Preview, select them all in the sidebar, use Adjust Size to change the size of all of them.
Am I misreading something in the OP?
He doesn’t want them at a fixed size. See my posts and his above. He has a folder of images in all different sizes that he wants to reduce by 2.5cm in one dimension and 2.7 cm in the other, without cropping and not constraining for aspect ratio. I’m not entirely sure I understand why, but that’s what’s being asked. So, basically, resize to original X dimension - 2.5cm and original Y dimension - 2.7 cm, do not crop, stretch to fit. And the X dimensions and Y dimensions within the same folder will vary, so it’s not a fixed width and height he wants it resized to, but a relative width and height.
I see.
Since you’ve done some scripting, it might be worth looking at Python and rolling your own. I know there are libraries specifically dealing with image manipulation. In the tiny bit I’ve dabbled with Python, I’ve never done image related tasks so that’s as much of a pointer as I can give.
This is what I’ve used since the 1980’s. Belongs on every Mac.
I used Graphicconverter for years, but it stopped working when I upgraded to Mavericks, and it doesn’t seem to be available for free any more (it used to be, the business model was that the program itself was free, but that the manual for it was for sale, which suited a tinkerer just fine).
No, it’s always been shareware, not freeware. I think your memory is faulty.
Have you examined PhotoResize Pro? I’m not sure if it can do this, but it has lots of options: