Matlab image spatial resolution, change pixel

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akevg akevg
akevg akevg 2022-3-19
评论： DGM 2022-3-20
Hi, how can ı change 8 bit image's pixel numbers like these? Help please

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Image Analyst
Image Analyst 2022-3-19
Ran in:
Try this. It will make sure the output image is exactly the same size as the input image.
inputImage = imread('peppers.png');
[inputRows, inputColumns, numColors] = size(inputImage)
inputRows = 384
inputColumns = 512
numColors = 3
for ii = 1:6
subplot(2,3,ii);
outputImage = imresize(inputImage,2^-(ii-1));
[rows, columns, numColors] = size(outputImage);
fprintf('After resizing once it is %d rows by %d columns\n', rows, columns);
% Resize output image again to match the input.
outputImage = imresize(outputImage, [inputRows, inputColumns], 'nearest');
% Update size.
[rows, columns, numColors] = size(outputImage);
fprintf(' After resizing twice it is again %d rows by %d columns\n', rows, columns);
imshow(outputImage);
% Show title with new size.
caption = sprintf('%d rows by %d columns', rows, columns);
axis('on', 'image')
title(caption)
end
After resizing once it is 384 rows by 512 columns
After resizing twice it is again 384 rows by 512 columns
After resizing once it is 192 rows by 256 columns
After resizing twice it is again 384 rows by 512 columns
After resizing once it is 96 rows by 128 columns
After resizing twice it is again 384 rows by 512 columns
After resizing once it is 48 rows by 64 columns
After resizing twice it is again 384 rows by 512 columns
After resizing once it is 24 rows by 32 columns
After resizing twice it is again 384 rows by 512 columns
After resizing once it is 12 rows by 16 columns
After resizing twice it is again 384 rows by 512 columns

更多回答（2 个）

Voss
Voss 2022-3-19
Ran in:
You can try imresize()
im = imread('image_1.png');
for ii = 1:6
subplot(2,3,ii);
imshow(imresize(im,2^-(ii-1)));
end
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DGM
DGM 2022-3-20
Ran in:
Or you could just do
inpict = imread('peppers.png');
k = 16;
outpict = imresize(imresize(inpict,1/k,'bilinear'),k,'nearest');
imshow(outpict)
[size(inpict); size(outpict)]
ans = 2×3
384 512 3 384 512 3
Which is far simpler and much faster than using blockproc() for any moderately large image.
Of course, it depends how much control one wants over exactly which pixels are contributing to each block and how exactly they're being weighted. I'm assuming that the goal here has no technical requirements, as none were given.

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Image Analyst
Image Analyst 2022-3-19
Use blockproc(). Solution attached.

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