图像处理的实现与应用（Scheme 版）

Scheme 是一种功能强大的函数式编程语言，适合用于图像处理和算法实验。本文将使用 Racket 实现一些基本的图像处理操作，包括灰度转换、去除边框和图像分割。

环境准备
首先，确保你已经安装了 Racket。可以在 Racket 官网 下载并安装。

加载图像
在 Racket 中，我们可以使用 racket/draw 库来加载和处理图像：

scheme

lang racket

(require racket/draw)

(define (load-image file-path)
(bitmap file-path))
灰度转换
将图像转换为灰度的过程如下：

scheme

(define (grayscale img)
(define width (send img get-width))
(define height (send img get-height))
(define gray-bitmap (make-bitmap width height))
(for ([y (in-range height)]
[x (in-range width)])
(define color (send img get-pixel x y))
(define r (color-red color))
(define g (color-green color))
(define b (color-blue color))
(define gray (round (+ (* r 0.3) (* g 0.59) (* b 0.11))))
(send gray-bitmap set-pixel x y (make-color gray gray gray)))
gray-bitmap)
去除图像边框
去除图像边框可以通过裁剪图像的边缘区域实现：

scheme
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(define (clear-borders img border-width)
(define width (send img get-width))
(define height (send img get-height))
(define new-bitmap (make-bitmap (- width (* 2 border-width))
(- height (* 2 border-width))))
(for ([y (in-range (+ border-width (- height border-width)))]
[x (in-range (+ border-width (- width border-width)))])
(define color (send img get-pixel x y))
(send new-bitmap set-pixel (- x border-width) (- y border-width) color))
new-bitmap)
图像分割
图像分割将图像按行列切分为多个小块：

scheme

(define (split-image img rows cols)
(define width (send img get-width))
(define height (send img get-height))
(define piece-width (/ width cols))
(define piece-height (/ height rows))
(for/list ([row (in-range rows)]
[col (in-range cols)])
(define new-bitmap (make-bitmap piece-width piece-height))
(for ([y (in-range piece-height)]
[x (in-range piece-width)])
(define color (send img get-pixel (+ (* col piece-width) x)
(+ (* row piece-height) y)))
(send new-bitmap set-pixel x y color))
new-bitmap))