The TIFF image file format has been around a long time, and lisp even longer. Yet, I couldn't find any common lisp libraries for reading TIFF images. Perhaps there's one out there I missed, but the only one I could find was my previous attempt, tiff-ffi, which consists of some wrapper functions around FFI calls to libtiff. I wanted a native common lisp TIFF library that wouldn't require the libtiff library so, at Robert Strandh's urging, I wrote retrospectiff.
Currently, there is no support for writing TIFF files, and only a fraction of the TIFF image formats are supported, but RGB and ARGB images, both uncompressed and with LZW compression, can be read. Grayscale support should come next and, hopefully, support for writing TIFF files before too long.