anchor.diff:                              nil nil sample x y)) ))))
   
   (defmethod pixels-translator (input-pixel-format output-pixel-format)
  -  (or ;; (gethash (list input-pixel-format output-pixel-format) *pixels-translator-cache*)
  +  (or (gethash (list input-pixel-format output-pixel-format) *pixels-translator-cache*)
         (setf (gethash (list input-pixel-format output-pixel-format) *pixels-translator-cache*)
               (compile
                nil
  
positive.code: 
  ;;;; Changes
  
  ;;;  When        Who    What
  ;;; --------------------------------------------------------------------------------------
  ;;;  2001-07-14  GB     created
  
  ;;;;
  
  
negative.code: ;; OUTPUT-PIXEL-FORMAT                                          [class]
  ;; IO-PIXEL-FORMAT                                              [class]
  
  (define-protocol-class pixel-format ()
    ((composer :initform nil)))
  
  (define-protocol-class input-pixel-format (pixel-format) 
    ())
  
  (define-protocol-class output-pixel-format (pixel-format)
    ())
  
  (define-protocol-class io-pixel-format (input-pixel-format output-pixel-format) ())
  
  (define-protocol-class uniform-pixel-format () ()
    ;; Mixin class for uniform pixel formats
    )
  
  (define-protocol-class non-uniform-pixel-format () ()
    ;; Mixin class for non-uniform pixel formats
    )
  
  ;; and their predicates
  
  ;; The protocol
  
  