Mosamic

Mosamic is a Mac application that helps you generate photo mosaics by using personal pictures or images from Flickr.

You can import as many photos as you like, easily configure the output settings according to your needs, and preview the mosaic before exporting it to your local directories.

In the main window of the application you will find a Tiles Library button. By clicking it, you reveal a separate window where you can import image folders from your Mac or pictures from the Flickr website. If you choose the second method, you need to enter a keyword in the search field and select the amount of images you wish to fetch from the aforementioned webpage.

The program features an assistant where you can configure the mosaic settings step-by-step. You can select the image you wish to turn into a photo mosaic, choose the preferred number of tiles, etc. Then, the application lets you preview the resulted image and export it to your local drive.

In my testing, the output quality was excellent. The utility ran flawlessly, without slowing down my Mac while generating the photo mosaic.

My only issue with this program is that it supports a limited amount of input and output formats. You can import only JPEG and PNG files and export the mosaic as a PNG image.

I'd say it's worth giving this utility a try if the aforementioned flaw doesn't mean much to you. The app works great, offers you quality results, and is free.