r11451: add test

[cl-photo.git] / dof.lisp

diff --git a/dof.lisp b/dof.lisp
index b937da03b19055df8c85133905be2bc4d355bf8d..8dfdf1478ac32981d9472a92fc1bb7d1d6e70e33 100644 (file)
--- a/dof.lisp
+++ b/dof.lisp
@@ -19,19 +19,29 @@
 
 (in-package #:photo)
 
+(defun sort-size (size)
+  "Returns a cons pair with the smaller size first."
+  (if (>= (car size) (cdr size))
+      (cons (cdr size) (car size))
+      (cons (car size) (cdr size))))
+  
+(defun print-magnification (imager-size print-size)
+  "Returns the magnification required between an imager and print sizes
+while taking crop into consideration."
+  (setf imager-size (sort-size imager-size))
+  (setf print-size (sort-size print-size))
+  (float (max (/ (car print-size) (car imager-size))
+             (/ (cdr print-size) (cdr print-size)))))
+
 (defun coc (imager-size &key (lpm 5) (minimum-distance 250) 
                    (viewing-distance 250)
                    (print-size (output-dimensions :8x10in)))
   "Returns circle of confusion in mm and print magnification for a format. 
 Default resolving power is 5 lpm at 25cm."
-
-  (let* ((imager-diagonal (diagonal (car imager-size) (cdr imager-size)))
-         (print-diagonal (diagonal (car print-size) (cdr print-size)))
-         (resolution-factor (/ (* lpm print-diagonal minimum-distance)
-                               (* imager-diagonal viewing-distance)))
-         (coc (/ 1.0d0 resolution-factor))
-         (print-magnification (/ print-diagonal imager-diagonal)))
-    (values coc print-magnification)))
+  (let* ((magnification (print-magnification imager-size print-size))
+        (resolution-factor (/ (* magnification lpm minimum-distance) viewing-distance))
+        (coc (/ 1.0d0 resolution-factor)))
+    (values coc magnification)))
 
 (defun coc-format (format &key (lpm 5) (minimum-distance 250) 
                           (viewing-distance 250)