matlab实现图像缩放

【实例截图】

【核心代码】

% MATLAB script for Assessment Item-1
% Task-1
clear; close all; clc;

%% Step-1: Load input image and conversion of input image to grey-scale image
I = imread('Zebra.jpg');
figure;
imshow(I);
title('Load input image', 'FontSize', 18);

Igray = rgb2gray(I);
figure;
imshow(Igray);
title('Conversion of input image to greyscale', 'FontSize', 18);

%% Step-2: Nearest-neighbor interpolation
n = 3;        % multiple of expand
[w,h] = size(Igray);        % the size of greyscale
Inearest = zeros(w*n,h*n);        % build a matrix which size is triple times of original image

for row1 = 1:w*n        % build a circluation to traverse every pixel
    for col1 = 1:h*n
        row = round(row1/n);        % copy the value of pixel based on index
        col = round(col1/n);
        
        if row<1
            row = 1;
        end
        if row > w
            row = w;
        end
        if col < 1
            col = 1;
        end
        if col > h
            col = h;
        end
        % ensure the index of pixel is positive integer
        
        Inearest(row1,col1) = Igray(row,col);        % use pixels of original image to fill output image
    end
end

Inearest=uint8(Inearest);       % Conversion of double to uint8

figure;
imshow(Inearest);
colorbar;
axis on;
title('Figure 1: Nearest-neighbor interpolation', 'FontSize', 22);

%% Step-3: Bilinear Interpolation
Ibilinear = zeros(w*n,h*n);        % build a matrix which size is triple times of original image

for row2 = 1:w*n        % build a circluation to traverse every pixel
    for col2 = 1:h*n
        
        row = row2/n;        % copy the value of pixel based on index
        col = col2/n;
        
        dec1 = row-floor(row);        % get fractional part for bilinear interpolation formula
        dec2 = col-floor(col);
        
        if row < 1
            row = 1;
        end
        if row > w
            row = w;
        end
        if col < 1
            col = 1;
        end
        if col > h
            col = h;
        end
        % ensure the index of pixel is positive integer
        
        Ibilinear(row2,col2) = (1-dec2)*(1-dec1)*Igray(floor(row),floor(col)) ...
            dec2*(1-dec1)*Igray(floor(row),ceil(col)) ...
            (1-dec2)*dec1*Igray(ceil(row),floor(col)) ...
            dec2*dec1*Igray(ceil(row),ceil(col));
        % use pixels of original image to fill output image based on bilinear interpolation formula
    end
end

Ibilinear = uint8(Ibilinear);       % Conversion of double to uint8

figure;
imshow(Ibilinear);
colorbar;
axis on;
title('Figure 2: Bilinear interpolation', 'FontSize', 22);