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 circle of confusion based on pixel size."
53 (when (and (consp imager) (consp pixels))
54 (values (float (* 2 (/ (car imager) (car pixels))))
55 (float (* 2 (/ (cdr imager) (cdr pixels)))))))
57 (defun coc-pixels-format (format)
58 "Returns circle of confusion based on pixel size."
59 (coc-pixels (imager-dimensions format) (pixel-dimensions format)))
61 (defun coc-airy (f-stop)
62 "Return the circle of confusion based on the airy disk."
63 (let ((airy (/ f-stop 1500)))
66 (defun dof-mm (focal-length f-stop distance coc &key (pupil-factor 1))
67 "Returns depth of field based on focal-length, f-stop, distance, and coc.
68 Six values are returned:
69 near point, far point, total dof, magnification, blur size at infinity (mm).
70 Circle of confusion can either be a number or keyword designating format."
71 (let* ((aperture (/ focal-length f-stop))
72 (numerator-1 (* (- pupil-factor 1) (- distance focal-length)
74 (numerator-2 (* pupil-factor aperture focal-length distance))
75 (denominator-1 (* pupil-factor coc (- distance focal-length)))
76 (denominator-2 (* pupil-factor aperture focal-length))
77 (near (/ (+ numerator-1 numerator-2)
78 (+ denominator-1 denominator-2)))
79 (far (/ (- numerator-1 numerator-2)
80 (- denominator-1 denominator-2)))
81 (mag (float (/ focal-length (- distance focal-length))))
82 (infinity-blur-diameter (/ (* mag focal-length) f-stop))
84 (values near far depth mag infinity-blur-diameter)))
86 ;; Simplified calculation for symmetric lens
87 (defun dof-symmetric-mm (focal-length f-stop distance coc)
88 "Returns depth of field based on focal-length, f-stop, distance, and coc.
89 Six values are returned:
90 near dof, far dof, total dof, near point, far point, magnification,
91 blur size at infinity (mm).
92 Circle of confusion can either be a number or keyword designating format.
93 Pupil factor is the ratio of the exit to enterance pupil diameters."
94 (let* ((aperture (/ focal-length f-stop))
95 (numerator (* distance coc (- distance focal-length)))
96 (factor-1 (* focal-length aperture))
97 (factor-2 (* coc (- distance focal-length)))
98 (near (- distance (/ numerator (+ factor-1 factor-2))))
99 (far (+ distance (/ numerator (- factor-1 factor-2))))
100 (mag (magnification focal-length distance))
101 (infinity-blur-diameter (/ (* mag focal-length) f-stop))
102 (depth (- far near)))
103 (values near far depth mag infinity-blur-diameter)))
105 (defun dof (focal-length f-stop distance coc &key (units :mm) (pupil-factor 1))
106 "Returns the Depth of Field.
107 Input: FOCAL-LENGTH, F-STOP, DISTANCE, CIRCLE-OF-CONFUSION.
108 Output: NEAR-POINT, FAR-POINT, TOTAL-DOF, MAGNIFICATION, BLUR-SIZE-OF-INFINITY-POINT-IN-MM."
109 (multiple-value-bind (near-point far-point total-dof mag blur)
110 (dof-mm focal-length f-stop (length->mm distance units) coc
111 :pupil-factor pupil-factor)
112 (values (mm->length near-point units)
113 (mm->length far-point units)
114 (mm->length total-dof units)
117 (defun hyperfocal (focal-length f-stop coc &key (units :mm))
118 (mm->length (+ focal-length (/ (* focal-length focal-length) f-stop coc)) units))
120 (defun effective-aperture (focal-length distance aperture)
121 (* aperture (bellows-factor focal-length distance)))