Imitatiting an Acorn resize action

I have a bunch of high-resolution images that I want to rescale for the Web.

  • Change the dpi to 92 (retina resolution)
  • KEEP the current image dimensions in inches.

I can do this in Acorn by selecting “Resize image…”, changing the units from pixels to inches, and then changing the resolution to 92. This throws away a bunch of information, which is what I want, to have the images look nice on the screen at their original size, but not be of such high quality that they’re worth printing out.

Is there an easy way to do this in Retrobatch? A script will do, of course; I just want a way to automate it. (I picked up Retrobatch anyway because I wanted thumbnails, and that was relatively easy…but I’d still like to be able to change the image to, e.g., what will fit in 3" by 5".

So I guess that’s actually two resizing questions…

The DPI node in Retrobatch will change the resolution of the image without touching any pixel data (ie - resizing the image). From what you’re saying, I believe that’s what you want?

Just a bit of info that you might already know, but I always like to throw out there: the DPI of an image is just a little bit of metadata that says how many pixels the app showing (or printing the image) is supposed to pack in an “inch”. So you can make an image print smaller by increasing the DPI. If an image is 72x72 pixels tall/wide, then a 72 dpi image will print out 1"x1". If the DPI is changed to 144, then that exact same image will now print out at 1/2"x1/2".

Anyway try out the DPI node, and if that doesn’t work let me know and I’m sure there’s some other way to do this.

If you are wanting to scale your images as well, then you can throw that node in there too.

I think the combo of DPI and scale you suggest will do it. I have 1200 dpi images (say) 6"x6". What I want out of the transform is an image that’s still 6" by 6" but at 92 dpi (retina browser resolution), so I think I need to use the DPI block (1200->92), which will expand the size of the image but put it to the DPI I want, and then use a resize block to resize it to .076 (92/1200) of the original size, still at the same DPI. I’ll try that and see how it comes out.

That sounds about right. I do want to point out one thing though - on the Mac, “Retina” @2x is 144 DPI (72*2). So I’m going to use that number for the following info:

Using the Scale node and having it resize to a width of 864 (which is 6 * 144), and then having a DPI node before or after that set to 144 should do the trick. In a browser you would set the image width to 432 (which is half of 864), and it’ll fill in all the @2x pixels nicely.