anchor.diff:                    '(62 62 62 62 62 62 62 62)
                     '(62 62 62 62 62 62 62 62)
                     '(62 62 62 62 62 62 62 62)))
  +
  +(defconstant +max-sample+ 255)
   
   )
   
  
positive.code:          (marker (interpret-markers image 0 stream)))
      (cond ((= +M_SOF0+ marker)
             (decode-frame image stream buffer)
             (when (and colorspace-conversion (= (descriptor-ncomp image) 3))
               (inverse-colorspace-convert image))
             (values (descriptor-buffer image)
                     (descriptor-height image)
                     (descriptor-width image)
  
negative.code:                 (setf (aref buffer pv) ; RED
                        (the uint8 (limit (plus yy (aref *cr-r-tab* cr)))))))))
  
  (defun ycck-cmyk-convert (image)
    (let* ((buffer (descriptor-buffer image))
           (nw (mul (descriptor-width image) 4)))
      (declare #.*optimize*
  	     (type (simple-array uint8 (*)) buffer)
               (type fixnum nw))
      (loop for y fixnum from 0 below (descriptor-height image)
         for yp fixnum from 0 by nw do
  	 (loop for x fixnum from 0 below (descriptor-width image)
  	    for py fixnum from yp by 4
  	    for pu fixnum = (1+ py)
  	    for pv fixnum = (plus py 2)
  	    for yy fixnum = (aref buffer py)
  	    for cb fixnum = (aref buffer pu)
  	    for cr fixnum = (aref buffer pv) do
  	      (setf (aref buffer pv)	; BLUE
  		    (the uint8 (limit (minus +max-sample+ (plus yy (aref *cb-b-tab* cb))))))
  	      (setf (aref buffer pu)	; GREEN
  		    (the uint8 (limit (minus +max-sample+
  					     (plus yy (ash (plus
  							    (aref *cb-g-tab* cb)
  							    (aref *cr-g-tab* cr))
  							   (- shift)))))))
  	      (setf (aref buffer py)	; RED
  		    (the uint8 (limit (minus +max-sample+ (plus yy (aref *cr-r-tab* cr))))))))))
  
  (defun allocate-buffer (height width ncomp)
    (make-array (* height width ncomp) 
  	      :element-type 'uint8
  