Honestly, what do you ask of a graphic viewer? Well, without doubt that it loads the largest possible number of different graphic formats, and in this respect you could consider Able Image Browser as one of the most complete.
Able Image Browser can read formats as unusual as PBM, PGM or PPM, and also the more popular ones like JPG, BMP, RLE, DIB, TIF, FAX, WMF, EMF, ICO, PNG, PCX, TGA, TARGA, VDA, ICB, VST or PIX. Apart from loading all these formats, you can save them directly in PDF, PostScript PS or EPS.
Able Image Browser also comes with tools to generate thumbnail galleries, resize the preview area, and it has a favourite images section, different printing options, utilities to rotate, cut, resize, apply filters, effects, etc.