Thumbnail images are small images typically used to preview larger images. They don't take long to download and you can see a lot of them on one page, so they're very useful in websites.

Our Drupal websites create thumbnails automatically but other systems don't - such as Joomla CMS and osCommerce online stores. So we've written this article to provide some tips on how to create a set of thumbnail images.

Creating thumbnail images in bulk

Many image manipulation programs will let you create a thumbnail image. But how do you create many, say 200, at once?
If you're using Windows, here's a free & easy way to do it:

1. Download, install and launch the free program Fresh View.
2. Navigate to the folder with the images to be converted using the tree view pane on the left.
3. Select the image(s) to be converted in the middle pane using shift-click & ctrl-click.
4. Select Tools | Convert & Resample, then in the resulting dialog box:
   1. Set Target Format to JPEG.
   2. In the Resampling box, set "Resample images to fit width 120 height 120" and Resampling Filter to "Mitchell Filter" or whatever filter you think works best with your images(s) (use Preview button to see).
   3. Press OK.
5. All selected files will be converted to the maximum dimensions of 120 x 120. You can use whatever size you like of course. Filenames of new files will be sequentially numbered and you should rename them, say with _t for thumbnail. Other file options are located in the "Filing" tab of the previous dialog box.

You should start with a set of large images for best results. The large images can be used directly for the large version. If too large, use Fresh View to reduce the size.

Advanced image editing

You can do much more advanced image editing using GIMP.
GIMP will let you create thumbnail images but also does much more, such as cropping, photo retouching and image composition. It's free, and works on Mac OSX and Unix as well as Windows.