From c9e757cf83865138421a9a09a6237fabbff2aab4 Mon Sep 17 00:00:00 2001
From: "Kevin M. Rosenberg" <kevin@rosenberg.net>
Date: Sat, 23 Apr 2005 10:42:57 +0000
Subject: [PATCH] r10456: add rayleigh

---
 cameras.lisp   |  7 ++++---
 doc/readme.lml |  4 ++--
 dof.lisp       | 21 +++++++++++++++------
 package.lisp   |  4 +++-
 4 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/cameras.lisp b/cameras.lisp
index 9b93505..293b219 100644
--- a/cameras.lisp
+++ b/cameras.lisp
@@ -112,9 +112,10 @@
   
 
 (defun format-match-p (format-spec format)
-  (when (or (eql format-spec (getf format :format))
-            (member format-spec (getf format :nicks)))
-    t))
+  (let ((key (ensure-keyword format-spec)))
+    (when (or (eql key (getf format :format))
+	      (member key (getf format :nicks)))
+      t)))
 
 (defun find-format (format-spec)
   (find format-spec +format-db+ :test 'format-match-p))
diff --git a/doc/readme.lml b/doc/readme.lml
index 509f598..3226931 100755
--- a/doc/readme.lml
+++ b/doc/readme.lml
@@ -35,8 +35,8 @@
      (:h2 "References")
      (:ul
       (:li
-       ((:a :href "http://solo.colorado.edu/~walawend/TwilightLandscapes/DoF_article.shtml")
-        "http://solo.colorado.edu/~walawend/TwilightLandscapes/DoF_article.shtml"))
+       ((:a :href "http://www.normankoren.com/Tutorials/MTF.html")
+        "http://www.normankoren.com/Tutorials/MTF.html"))
       (:li
        ((:a :href "http://www.vanwalree.com/optics/dofderivation.html")
         "http://www.vanwalree.com/optics/dofderivation.html"))
diff --git a/dof.lisp b/dof.lisp
index a98b90a..5dfc5dd 100644
--- a/dof.lisp
+++ b/dof.lisp
@@ -49,19 +49,28 @@ Default resolving power is 5 lpm at 25cm."
     (values coc print-magnification)))
 
 (defun coc-pixels (imager pixels)
-  "Returns circle of confusion based on pixel size."
+  "Returns lpm and circle of confusion based on pixel size."
   (when (and (consp imager) (consp pixels))
-    (values (float (* 2 (/ (car imager) (car pixels))))
-            (float (* 2 (/ (cdr imager) (cdr pixels)))))))
+    (let ((coc-w (float (* 2 (/ (car imager) (car pixels)))))
+	  (coc-h (float (* 2 (/ (cdr imager) (cdr pixels))))))
+    (values coc-w coc-h (/ 1. coc-w) (/ 1. coc-h)))))
   
 (defun coc-pixels-format (format)
   "Returns circle of confusion based on pixel size."
   (coc-pixels (imager-dimensions format) (pixel-dimensions format)))
 
-(defun coc-airy (f-stop)
+(defun coc-airy (f-stop &optional (wavelength 0.000512))
   "Return the circle of confusion based on the airy disk."
-  (let ((airy (/ f-stop 1500)))
-    (float (* 2 airy))))
+  (float (/ 1 (rayleigh-limit f-stop wavelength))))
+
+(defun rayleigh-limit (f-stop &optional (wavelength 0.0005))
+  "Returns the rayleigh limit in line pairs per mm (MTF 9%) as well as the MTF50"
+  (let ((rayleigh (float (/ 1 1.22 f-stop wavelength))))
+    (values rayleigh (* 0.46 rayleigh))))
+
+(defun maximum-sharpness-aperture (format &optional (wavelength 0.0005))
+  (multiple-value-bind (coc-w coc-h lpm-w lpm-h) (coc-pixels-format format)
+    (/ 1. (* 1.22 wavelength (/ (min lpm-w lpm-h) 0.46)))))
 
 (defun dof-mm (focal-length f-stop distance coc &key (pupil-factor 1))
   "Returns depth of field based on focal-length, f-stop, distance, and coc.
diff --git a/package.lisp b/package.lisp
index 0b9d3ea..093e46f 100644
--- a/package.lisp
+++ b/package.lisp
@@ -48,7 +48,9 @@
    #:dof
    #:hyperfocal
    #:effective-aperture
-
+   #:rayleigh-limit
+   #:maximum-sharpness-calculator
+   
    ;; tables.lisp
    #:hyperfocal-table
    #:aov-table
-- 
2.34.1