As you already know, a PDF can - if at all – be corrected, edited or retouched only with great difficulty after its
finalisation; as there is no such thing as a PDF-Editor. In order to be able to edit a PDF document with an image processing program like Adobe Photoshop, you would first have to allow this program
to raster the PDF document, but then again, this would
make the document loose its PDF character.
On the other hand, the TIFF files provided by EXTIF
pro can be easily and conveniently
edited in any image processing program, of
course offering opportunity to retouch each single
color channel separately.