;;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10; Package: photo -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          dof.lisp
;;;; Purpose:       Depth of field functions for cl-photo
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  April 2005
;;;;
;;;; $Id$
;;;;
;;;; This file, part of cl-photo, is Copyright (c) 2005 by Kevin M. Rosenberg
;;;;
;;;; cl-photo users are granted the rights to distribute and use this software
;;;; as governed by the terms of the GNU General Public License v2
;;;; (http://www.gnu.org/licenses/gpl.html)
;;;;
;;;; *************************************************************************

(in-package #:photo)


(defun coc-format (format &key (lpm 5) (minimum-distance 250) 
                          (viewing-distance 250)
                          (print-size (format-dimensions :8x10in)))
  "Returns circle of confusion in mm and print magnification for a format. 
Default resolving power is 5 lpm at 25cm."

  (let* ((format-size (format-dimensions format))
         (format-diagonal (diagonal (car format-size) (cdr format-size)))
         (print-diagonal (diagonal (car print-size) (cdr print-size)))
         (resolution-factor (/ (* lpm print-diagonal minimum-distance)
                               (* format-diagonal viewing-distance)))
         (coc (/ 1.0d0 resolution-factor))
         (print-magnification (/ print-diagonal format-diagonal)))
    (values coc print-magnification)))

(defun coc-sensor (format nx ny)
  "Returns circle of confusion based on pixel size."
  (let* ((dim (format-dimensions format))
         (pixel-width (/ (car dim) nx))
         (pixel-height (/ (cdr dim) ny))) 
    (values (float (* 2 pixel-width))
            (float (* 2 pixel-height)))))

(defun coc-sensor-camera (camera &key (format :aps))
  (let ((dim (sensor-dimensions camera :format format)))
    (coc-sensor format (car dim) (cdr dim))))

(defun sensor-dimensions-megapixels (format megapixels)
  (let* ((dim (format-dimensions format))
         (aspect-ratio (/ (car dim) (cdr dim)))
         (width (round (sqrt (* aspect-ratio 1000000 megapixels)))))
    (cons width (round (/ width aspect-ratio)))))


(defun sensor-dimensions (sensor-spec &key (format :aps))
  "Returns the number of pixels for a sensor. 
CAMERA-SPEC is either a keyword designating the camera or
the number of megapixels of the sensor.
FORMAT should be defined if the CAMERA-SPEC is the number of megapixels
so the proper aspect ratio is used."
  (etypecase sensor-spec
    (keyword
     (ecase sensor-spec
       ;; nikon
       (:d2x (cons 4288 2848))
       (:d100 (cons 3037 2024))
       (:d2h (cons 2464 1632))
       (:d70 (cons 3008 2000))

       ;; canon
       (:1d (cons 2464 1648))
       (:1d2 (cons 3504 2336))
       (:1ds (cons 4064 2704))
       (:1ds2 (cons 4992 3328))

       ))
    (number
     (sensor-dimensions-megapixels format sensor-spec))))

(defun coc-airy (f-stop)
  "Return the circle of confusion based on the airy disk."
  (let ((airy (/ f-stop 1500)))
    (float (* 2 airy))))

(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.
Six values are returned:
near dof, far dof, total dof, near point, far point, magnification,
blur size at infinity (mm).
Circle of confusion can either be a number or keyword designating format."
  (let* ((aperture (/ focal-length f-stop)) 
         (numerator-1 (* (- pupil-factor 1) (- distance focal-length)
                         coc focal-length))
         (numerator-2 (* pupil-factor aperture focal-length distance))
         (denominator-1 (* pupil-factor coc (- distance focal-length)))
         (denominator-2 (* pupil-factor aperture focal-length))
         (near (/ (+ numerator-1 numerator-2)
                  (+ denominator-1 denominator-2)))
         (far (/ (- numerator-1 numerator-2)
                 (- denominator-1 denominator-2)))
         (mag (float (/ focal-length (- distance focal-length))))
         (infinity-blur-diameter (/ (* mag focal-length) f-stop))
         (depth (- far near)))
    (values near far depth mag infinity-blur-diameter)))

;; Simplified calculation for symmetric lens
(defun dof-symmetric-mm (focal-length f-stop distance coc)
  "Returns depth of field based on focal-length, f-stop, distance, and coc.
Six values are returned:
near dof, far dof, total dof, near point, far point, magnification,
blur size at infinity (mm).
Circle of confusion can either be a number or keyword designating format.
Pupil factor is the ratio of the exit to enterance pupil diameters."
  (let* ((aperture (/ focal-length f-stop))
         (numerator (* distance coc (- distance focal-length)))
         (factor-1 (* focal-length aperture))
         (factor-2 (* coc (- distance focal-length)))
         (near (- distance (/ numerator (+ factor-1 factor-2))))
         (far (+ distance (/ numerator (- factor-1 factor-2))))
         (mag (magnification focal-length distance))
         (infinity-blur-diameter (/ (* mag focal-length) f-stop))
         (depth (- far near)))
    (values near far depth mag infinity-blur-diameter)))

(defun dof (focal-length f-stop distance coc &key (units :mm) (pupil-factor 1))
  (multiple-value-bind (near-point far-point total-dof mag blur)
      (dof-mm focal-length f-stop (length->mm distance units) coc 
              :pupil-factor pupil-factor)
    (values (mm->length near-point units)
            (mm->length far-point units)
            (mm->length total-dof units)
            mag blur)))

(defun hyperfocal (focal-length f-stop coc &key (units :mm))
  (mm->length 
   (+ focal-length (/ (* focal-length focal-length) f-stop coc))
   units))

(defun magnification (focal-length distance)
  (float (/ focal-length (- distance focal-length))))

(defun bellows-factor (focal-length distance)
  (1+ (magnification focal-length distance)))

(defun effective-aperture (focal-length distance aperture)
  (* aperture (bellows-factor focal-length distance)))