ToyViewer

If you're looking for a powerful image viewer with excellent editing functions and image converting filters, then ToyViewer is definitely worth checking out. One of the best things about ToyViewer is that once it's installed on your Mac, you can use it to see image files in different formats on other Cocoa applications.

Not only can ToyViewer read and display image files in different formats, including tiff, gif, bmp, png, jpg, bie (jbig), pcx, pcd, pict, pnm (ppm, pbm, or pgm), xbm, mag, SUN Rasterfile, JPEG2000 (jp2, jpc, j2k), and other formats supported by Mac OS X, but it also allows you to save your displayed images in various formats such as tiff, pdf, gif, bmp, png, jpg, JPEG2000, bie (jbig), pnm, or xbm.

In addition to these features, ToyViewer allows you to scan (auto-display) image files in a folder and view images in full-screen size. You can also scale (enlarge/shrink), rotate, flip, or clip images to your liking.

Overall, if you're looking for a versatile, easy-to-use image viewer with impressive editing functions and compatibility with different image formats, then ToyViewer is definitely a program you should consider.