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 ;;;; *************************************************************************
23 (defun coc-format (format &key (lpm 5) (minimum-distance 250)
24 (viewing-distance 250)
25 (print-size (format-dimensions :8x10in)))
26 "Returns circle of confusion in mm and print magnification for a format.
27 Default resolving power is 5 lpm at 25cm."
29 (let* ((format-size (format-dimensions format))
30 (format-diagonal (diagonal (car format-size) (cdr format-size)))
31 (print-diagonal (diagonal (car print-size) (cdr print-size)))
32 (resolution-factor (/ (* lpm print-diagonal minimum-distance)
33 (* format-diagonal viewing-distance)))
34 (coc (/ 1.0d0 resolution-factor))
35 (print-magnification (/ print-diagonal format-diagonal)))
36 (values coc print-magnification)))
38 (defun coc-sensor (format nx ny)
39 "Returns circle of confusion based on pixel size."
40 (let* ((dim (format-dimensions format))
41 (pixel-width (/ (car dim) nx))
42 (pixel-height (/ (cdr dim) ny)))
43 (values (float (* 2 pixel-width))
44 (float (* 2 pixel-height)))))
46 (defun coc-sensor-camera (camera &key (format :aps))
47 (let ((dim (sensor-dimensions camera :format format)))
48 (coc-sensor format (car dim) (cdr dim))))
54 (defun coc-airy (f-stop)
55 "Return the circle of confusion based on the airy disk."
56 (let ((airy (/ f-stop 1500)))
59 (defun dof-mm (focal-length f-stop distance coc &key (pupil-factor 1))
60 "Returns depth of field based on focal-length, f-stop, distance, and coc.
61 Six values are returned:
62 near dof, far dof, total dof, near point, far point, magnification,
63 blur size at infinity (mm).
64 Circle of confusion can either be a number or keyword designating format."
65 (let* ((aperture (/ focal-length f-stop))
66 (numerator-1 (* (- pupil-factor 1) (- distance focal-length)
68 (numerator-2 (* pupil-factor aperture focal-length distance))
69 (denominator-1 (* pupil-factor coc (- distance focal-length)))
70 (denominator-2 (* pupil-factor aperture focal-length))
71 (near (/ (+ numerator-1 numerator-2)
72 (+ denominator-1 denominator-2)))
73 (far (/ (- numerator-1 numerator-2)
74 (- denominator-1 denominator-2)))
75 (mag (float (/ focal-length (- distance focal-length))))
76 (infinity-blur-diameter (/ (* mag focal-length) f-stop))
78 (values near far depth mag infinity-blur-diameter)))
80 ;; Simplified calculation for symmetric lens
81 (defun dof-symmetric-mm (focal-length f-stop distance coc)
82 "Returns depth of field based on focal-length, f-stop, distance, and coc.
83 Six values are returned:
84 near dof, far dof, total dof, near point, far point, magnification,
85 blur size at infinity (mm).
86 Circle of confusion can either be a number or keyword designating format.
87 Pupil factor is the ratio of the exit to enterance pupil diameters."
88 (let* ((aperture (/ focal-length f-stop))
89 (numerator (* distance coc (- distance focal-length)))
90 (factor-1 (* focal-length aperture))
91 (factor-2 (* coc (- distance focal-length)))
92 (near (- distance (/ numerator (+ factor-1 factor-2))))
93 (far (+ distance (/ numerator (- factor-1 factor-2))))
94 (mag (magnification focal-length distance))
95 (infinity-blur-diameter (/ (* mag focal-length) f-stop))
97 (values near far depth mag infinity-blur-diameter)))
99 (defun dof (focal-length f-stop distance coc &key (units :mm) (pupil-factor 1))
100 (multiple-value-bind (near-point far-point total-dof mag blur)
101 (dof-mm focal-length f-stop (length->mm distance units) coc
102 :pupil-factor pupil-factor)
103 (values (mm->length near-point units)
104 (mm->length far-point units)
105 (mm->length total-dof units)
108 (defun hyperfocal (focal-length f-stop coc &key (units :mm))
110 (+ focal-length (/ (* focal-length focal-length) f-stop coc))
113 (defun magnification (focal-length distance)
114 (float (/ focal-length (- distance focal-length))))
116 (defun bellows-factor (focal-length distance)
117 (1+ (magnification focal-length distance)))
119 (defun effective-aperture (focal-length distance aperture)
120 (* aperture (bellows-factor focal-length distance)))