1 ;;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10; Package: photo -*-
2 ;;;; *************************************************************************
3 ;;;; FILE IDENTIFICATION
6 ;;;; Purpose: Depth of field functions for cl-photo
7 ;;;; Programmer: Kevin M. Rosenberg
8 ;;;; Date Started: April 2005
12 ;;;; This file, part of cl-photo, is Copyright (c) 2005 by Kevin M. Rosenberg
14 ;;;; cl-photo users are granted the rights to distribute and use this software
15 ;;;; as governed by the terms of the GNU General Public License v2
16 ;;;; (http://www.gnu.org/licenses/gpl.html)
18 ;;;; *************************************************************************
22 (defun coc (imager-size &key (lpm 5) (minimum-distance 250)
23 (viewing-distance 250)
24 (print-size (output-dimensions :8x10in)))
25 "Returns circle of confusion in mm and print magnification for a format.
26 Default resolving power is 5 lpm at 25cm."
28 (let* ((imager-diagonal (diagonal (car imager-size) (cdr imager-size)))
29 (print-diagonal (diagonal (car print-size) (cdr print-size)))
30 (resolution-factor (/ (* lpm print-diagonal minimum-distance)
31 (* imager-diagonal viewing-distance)))
32 (coc (/ 1.0d0 resolution-factor))
33 (print-magnification (/ print-diagonal imager-diagonal)))
34 (values coc print-magnification)))
36 (defun coc-format (format &key (lpm 5) (minimum-distance 250)
37 (viewing-distance 250)
38 (print-size (output-dimensions :8x10in)))
39 "Returns circle of confusion in mm and print magnification for a format.
40 Default resolving power is 5 lpm at 25cm."
42 (let* ((format-size (imager-dimensions format))
43 (format-diagonal (diagonal (car format-size) (cdr format-size)))
44 (print-diagonal (diagonal (car print-size) (cdr print-size)))
45 (resolution-factor (/ (* lpm print-diagonal minimum-distance)
46 (* format-diagonal viewing-distance)))
47 (coc (/ 1.0d0 resolution-factor))
48 (print-magnification (/ print-diagonal format-diagonal)))
49 (values coc print-magnification)))
51 (defun coc-pixels (imager pixels)
52 "Returns lpm and circle of confusion based on pixel size."
53 (when (and (consp imager) (consp pixels))
54 (let ((coc-w (float (* 2 (/ (car imager) (car pixels)))))
55 (coc-h (float (* 2 (/ (cdr imager) (cdr pixels))))))
56 (values coc-w coc-h (/ 1. coc-w) (/ 1. coc-h)))))
58 (defun coc-pixels-format (format)
59 "Returns circle of confusion based on pixel size."
60 (coc-pixels (imager-dimensions format) (pixel-dimensions format)))
62 (defun coc-airy (f-stop &optional (wavelength 0.000512))
63 "Return the circle of confusion based on the airy disk."
64 (float (/ 1 (rayleigh-limit f-stop wavelength))))
66 (defun rayleigh-limit (f-stop &optional (wavelength 0.0005))
67 "Returns the rayleigh limit in line pairs per mm (MTF 9%) as well as the MTF50"
68 (let ((rayleigh (float (/ 1 1.22 f-stop wavelength))))
69 (values rayleigh (* 0.46 rayleigh))))
71 (defun maximum-sharpness-aperture (format &optional (wavelength 0.0005))
72 (multiple-value-bind (coc-w coc-h lpm-w lpm-h) (coc-pixels-format format)
73 (/ 1. (* 1.22 wavelength (/ (min lpm-w lpm-h) 0.46)))))
75 (defun dof-mm (focal-length f-stop distance coc &key (pupil-factor 1))
76 "Returns depth of field based on focal-length, f-stop, distance, and coc.
77 Six values are returned:
78 near point, far point, total dof, magnification, blur size at infinity (mm).
79 Circle of confusion can either be a number or keyword designating format."
80 (let* ((aperture (/ focal-length f-stop))
81 (numerator-1 (* (- pupil-factor 1) (- distance focal-length)
83 (numerator-2 (* pupil-factor aperture focal-length distance))
84 (denominator-1 (* pupil-factor coc (- distance focal-length)))
85 (denominator-2 (* pupil-factor aperture focal-length))
86 (near (/ (+ numerator-1 numerator-2)
87 (+ denominator-1 denominator-2)))
88 (far (/ (- numerator-1 numerator-2)
89 (- denominator-1 denominator-2)))
90 (mag (float (/ focal-length (- distance focal-length))))
91 (infinity-blur-diameter (/ (* mag focal-length) f-stop))
93 (values near far depth mag infinity-blur-diameter)))
95 ;; Simplified calculation for symmetric lens
96 (defun dof-symmetric-mm (focal-length f-stop distance coc)
97 "Returns depth of field based on focal-length, f-stop, distance, and coc.
98 Six values are returned:
99 near dof, far dof, total dof, near point, far point, magnification,
100 blur size at infinity (mm).
101 Circle of confusion can either be a number or keyword designating format.
102 Pupil factor is the ratio of the exit to enterance pupil diameters."
103 (let* ((aperture (/ focal-length f-stop))
104 (numerator (* distance coc (- distance focal-length)))
105 (factor-1 (* focal-length aperture))
106 (factor-2 (* coc (- distance focal-length)))
107 (near (- distance (/ numerator (+ factor-1 factor-2))))
108 (far (+ distance (/ numerator (- factor-1 factor-2))))
109 (mag (magnification focal-length distance))
110 (infinity-blur-diameter (/ (* mag focal-length) f-stop))
111 (depth (- far near)))
112 (values near far depth mag infinity-blur-diameter)))
114 (defun dof (focal-length f-stop distance coc &key (units :mm) (pupil-factor 1))
115 "Returns the Depth of Field.
116 Input: FOCAL-LENGTH, F-STOP, DISTANCE, CIRCLE-OF-CONFUSION.
117 Output: NEAR-POINT, FAR-POINT, TOTAL-DOF, MAGNIFICATION, BLUR-SIZE-OF-INFINITY-POINT-IN-MM."
118 (multiple-value-bind (near-point far-point total-dof mag blur)
119 (dof-mm focal-length f-stop (length->mm distance units) coc
120 :pupil-factor pupil-factor)
121 (values (mm->length near-point units)
122 (mm->length far-point units)
123 (mm->length total-dof units)
126 (defun hyperfocal (focal-length f-stop coc &key (units :mm))
127 (mm->length (+ focal-length (/ (* focal-length focal-length) f-stop coc)) units))
129 (defun effective-aperture (focal-length distance aperture)
130 (* aperture (bellows-factor focal-length distance)))