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I need a "good" thumbnail generator for Mac. Any suggestions?

Some criteria:

  • Must support common image formats(ie png,jpg,etc.).
  • Easy to use.
  • Support large image files.
  • Free and/or not crippled.
  • Must be able to do files and directories if needed.

The software's sole purpose should be to output thumbnails.


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Is there a particular purpose for said thumbnail generator? – digitxp Nov 16 '10 at 22:47
@digitxp - I'm currently working on something where I have hundreds of large jpgs and I need to get them in a thumbnail size and in various formats. I need a non-tedious way to accomplish this. – ricbax Nov 16 '10 at 23:01
How about Automator? – Daniel Beck Nov 16 '10 at 23:09
up vote 2 down vote accepted

support the mac developers, buy a copy of Downsize or you could use automator...

ps. I'm NOT affiliated to Stunt Software.

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I would use ImageMagick for this. Here's a link to the OS X installation instructions. It is certainly not its sole purpose to generate thumbnails, but you can script a command for this based on numerous examples at the ImageMagick website. An example command would be:

convert -define jpeg:size=500x180  hatching_orig.jpg  -auto-orient \
      -thumbnail 250x90   -unsharp 0x.5  thumbnail.gif

Batch processing can be achieved using something like:

mogrify  -path thumbnails -thumbnail 100x100  *

These are only examples and you should check all the ImageMagick options relevant to the images that you will be processing.

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+1 Any other programs suggested may very well do the same thing by using ImageMagick to do it. – paradroid Nov 17 '10 at 1:23
Not quite too far up on the 'easy to use' category though. – digitxp Nov 18 '10 at 12:37
Personal opinion, but on the contrary, I find this easiest to use. – fideli Nov 18 '10 at 14:16

I would use automator, so you would create a workflow that looks something like this: workflow](

First, you insert a get selected finder items action, so that the computer knows what files to work with.

Next, add a duplicate finder items action, because we don't want to replace the originals!

Next, we add a rename finder items action, and set it to replace text in the drop down box at the top. This is because the perevious step appends the word "copy" to the name of each file it duplicates, but I don't want them to say copy, I want them to be the file name followed by an underscore followed by the letters "sm", which stands for small, because these are the small images. So in the find field, we type a space then the word copy, so it looks like this Find: [ copy]. Then we type _sm in the replace field, so it looks like this Replace: [_sm]

Then, we add a crop images action, because that is our final goal: to crop them into thumbnails. Make sure the drop down box at the top says "to dimensions". Then, enter the dimensions of your desired thumbnails in the appropriate fields. Then, before you click run, make sure to set the scale before crop drop down box to Scale to Short Side, so it looks like this Scale before crop: [Scale to Short Side]. That way, the thumbnail will be a scaled down version of the image that fills the thumbnail box, rather than just being a tiny portion of the image.

Finally, find your images that you need thumbnails of in the finder, select all of them by either command clicking them or using the cmd+a shortcut to select them all, then press run!

There you go! You're all set with brand spankin new thumbnails.

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Nice idea! Sometimes it pays off to spend time with Automator. ;-) – Shawn Spencer Feb 19 '14 at 19:30

NIT Resize & Watermark works on Mac and Windows exactly the same, requires Adobe Air but it's automatically installed.

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ImageXY might be perfect for you - does everything that you want without the overly complex interface that most image resizers have.

Disclosure: I am the author of ImageXY.

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Graphic converter - the swiss army knife for image handling in MacOS X could also be used. See here:

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