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Ingy döt Net 2023-07-01 11:58:00 -04:00
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Task/Grayscale-image/Common-Lisp/grayscale-image.lisp Normal file
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(in-package #:rgb-pixel-buffer)
(defun rgb-to-gray-image (rgb-image)
(flet ((rgb-to-gray (rgb-value)
(round (+ (* 0.2126 (rgb-pixel-red rgb-value))
(* 0.7152 (rgb-pixel-green rgb-value))
(* 0.0722 (rgb-pixel-blue rgb-value))))))
(let ((gray-image (make-array (array-dimensions rgb-image) :element-type '(unsigned-byte 8))))
(dotimes (i (array-total-size rgb-image))
(setf (row-major-aref gray-image i) (rgb-to-gray (row-major-aref rgb-image i))))
gray-image)))
(export 'rgb-to-gray-image)
(defun grayscale-image-to-pgm-file (image file-name &optional (max-value 255))
(with-open-file (p file-name :direction :output
:if-exists :supersede)
(format p "P2 ~&~A ~A ~&~A" (array-dimension image 1) (array-dimension image 0) max-value)
(dotimes (i (array-total-size image))
(print (row-major-aref image i) p))))
(export 'grayscale-image-to-pgm-file)