function to decrease image size

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Altina Rexha
Altina Rexha 2020-9-28
评论： Altina Rexha 2020-9-28
function [y] = ImageDecrease(i,n)
y=imresize(i,n);
size(y)
end
I need to create a function to decrease the image size. Ex. image size is 512px x 512px and if n=4 the size of image has to be 64x64 (the i parameter is the image)
This function doesnt work bc if scale is >1 it increases the image..

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Image Analyst
Image Analyst 2020-9-28
I know it sounds obvious, so you've probably already done it by now, but did you try inverting the number:
function outputImage = ImageDecrease(inputImage, n)
[rows, columns, numberOfColorChannels] = size(inputImage);
fprintf('Input image has %d rows, %d columns, and %d color channels',rows, columns, numberOfColorChannels)
outputImage = imresize(inputImage, 1/n);
[rows, columns, numberOfColorChannels] = size(outputImage);
fprintf('Output image has %d rows, %d columns, and %d color channels',rows, columns, numberOfColorChannels)
end
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Image Analyst
Image Analyst 2020-9-28
It DOES work. And using imresize is not a bad idea.
rgbImage = imread('Peppers.png');
subplot(2, 1, 1);
imshow(rgbImage);
axis('on', 'image');
outputImage = ImageDecrease(rgbImage, 4);
subplot(2, 1, 2);
imshow(outputImage);
axis('on', 'image');
function outputImage = ImageDecrease(inputImage, n)
[rows, columns, numberOfColorChannels] = size(inputImage);
fprintf('Input image has %d rows, %d columns, and %d color channels',rows, columns, numberOfColorChannels)
outputImage = imresize(inputImage, 1/n);
[rows, columns, numberOfColorChannels] = size(outputImage);
fprintf('Output image has %d rows, %d columns, and %d color channels',rows, columns, numberOfColorChannels)
end
Note on the axes how the number of colums goes from 512 to 128, indicating a reduction by a factor of 4.
You can also pass in the exact number of rows and columns you want, if you prefer that way.
outputImage = imresize(inputImage, [123, 456]); % Make 123 rows by 456 columns.

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