matlab编写一个函数来反转PGM图像的灰度等级（即创建图像的底片）

好的，以下是一个简单的MATLAB函数，可以用来反转PGM图像的灰度等级：

function [invertedImage] = invertPGM(image)
% INVERTPGM takes a PGM image as input and returns its inverted version.
% The inverted image is obtained by subtracting the gray level of each pixel from
% the maximum gray level present in the image.

% Read the image and extract the maximum gray level
[~, ~, maxValue] = imread(image);

% Compute the inverted image
invertedImage = maxValue - double(imread(image));

% Display the original and the inverted image side by side
figure;
subplot(1,2,1);
imshow(image);
title('Original Image');
subplot(1,2,2);
imshow(invertedImage);
title('Inverted Image');

end

你可以将你的PGM图像的路径作为输入传递给这个函数，它将返回反转的图像。请注意，此函数仅适用于PGM图像，对于其他格式的图像需要进行相应的修改。