圖像灰度變換

im = imread('pout.tif');
im = double(im) / 255.0;
myimshow(im, 'Original Image');

im1 = imadjust(im);
myimshow(im1, '灰度拉伸');

im2 = imadjust(im, [min(min(im)); max(max(im))], [], 0.4);
myimshow(im2, '\gamma 變換, \gamma = 0.4');

im3 = imadjust(im, [min(min(im)); max(max(im))], [], 2.5);
myimshow(im3, '\gamma 變換, \gamma = 2.5');

im1 = imadjust(im);
myimshow(im1, '灰度拉伸');

im2 = imadjust(im, [min(min(im)); max(max(im))], [], 0.4);
myimshow(im2, '\gamma 變換, \gamma = 0.4');

im3 = imadjust(im, [min(min(im)); max(max(im))], [], 2.5);
myimshow(im3, '\gamma 變換, \gamma = 2.5');

計算顯示圖像直方圖、直方圖均衡化

im = imread('tire.tif');
myimshow(im, '原圖');

im_eq = histeq(im);
myimshow(im_eq, '直方圖均衡化');

空間域圖像平滑、銳化

im = imread('pout.tif');
im = double(im)/255;

figure;
subplot(221);
imshow(im);
title('Original Image')

index = 2;
for N = [3, 7, 15]
    kernel = ones(N) / N^2;
    im_blur = imfilter(im, kernel);
    subplot(2, 2, index);
    index = index + 1;
    imshow(im_blur);
    title(['Kernel size:', num2str(N)])
end
suptitle('Blur');

im = imread('rice.png');
im = double(im)/255;

figure, subplot(221);
imshow(im);title('Original Image');

kernel = [0 1 0; 1 -4 1; 0 1 0];
im_edge = imfilter(im, kernel);
subplot(222);
imshow(im_edge);
title('Uncalibrated');

im_edge = im_edge - min(min(im_edge));
subplot(223);
imshow(mat2gray(im_edge));
title('Calibrated');

im_sharpen = mat2gray(im - 0.5*im_edge);
subplot(224);
imshow(im_sharpen);
title('Sharpened');
suptitle('Sharpen');

function myimshow(im, im_title)
    figure;
    subplot(121);
    imshow(im);
    subplot(122);
    imhist(im);
    suptitle(im_title);
end