r10456: add rayleigh

[cl-photo.git] / dof.lisp

diff --git a/dof.lisp b/dof.lisp
index a98b90a23bbd8ecf738ae5d70c43c69786c04cc7..5dfc5dd06e0dac523d29400f0bc58dd9f2152444 100644 (file)
--- 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.