为什么OpenCV cv2.resize提供的答案不同于MATLAB imresize? [英] why OpenCV cv2.resize gives different answer than MATLAB imresize?
问题描述
我正在将MATLAB代码传输到python并尝试使用OpenCV函数 cv2.resize
缩小图像,但是我得到了与MATLAB输出不同的结果。 / p>
为了确保我的代码在调整大小之前没有做错,我在两个函数上都使用了一个小例子并比较了输出。
我首先在Python和MATLAB中创建了以下数组并对其进行了上采样:
Python - NumPy和OpenCV
x = cv2.resize(np.array([[1,2],[3,4]]),(4,4),interpolation = cv2.INTER_LINEAR)
打印x
[[1. 1.25 1.75 2.]
[1.5 1.75 2.25 2.5]
[2.5 2.75 3.25 3.5]
[3. 3.25 3.75 4.]]
MATLAB
x = imresize([1,2; 3,4],[4,4],'bilinear')
ans =
1.0000 1.2500 1.7500 2.0000
1.5000 1.7500 2.2500 2.500 0
2.5000 2.7500 3.2500 3.5000
3.0000 3.2500 3.7500 4.0000
然后我拿了回答并将它们调整回原来的2x2大小。
Python:
cv2.resize(x,(2,2),interpolation = cv2.INTER_LINEAR)
ans =
[[1.375,2.125],
[ 2.875,3.625]]
MATLAB:
imresize(x,[2,2],'bilinear')
ans =
1.5625 2.1875
2.8125 3.4375
它们显然不一样,当数字越大时,答案就越不同了。
任何解释或资源都将受到赞赏。
MATLAB的< a href =http://www.mathworks.com/help/images/ref/imresize.html =nofollow noreferrer> imresize
默认启用抗锯齿:
>> imresize(x,[2,2],'bilinear')
ans =
1.5625 2.1875
2.8125 3.4375
>> imresize(x,[2,2],'bilinear','AntiAliasing',false)
ans =
1.3750 2.1250
2.8750 3.6250
过去曾试图重现仅使用 interp2
imresize
的结果。
I'm transferring a MATLAB code into python and trying to downscale an image using OpenCV function cv2.resize
, But I get a different results from what MATLAB outputs.
To make sure that my code is not doing anything wrong before the resize, I used a small example on both functions and compared the output.
I first created the following array in both Python and MATLAB and upsampled it:
Python - NumPy and OpenCV
x = cv2.resize(np.array([[1.,2],[3,4]]),(4,4), interpolation=cv2.INTER_LINEAR)
print x
[[ 1. 1.25 1.75 2. ]
[ 1.5 1.75 2.25 2.5 ]
[ 2.5 2.75 3.25 3.5 ]
[ 3. 3.25 3.75 4. ]]
MATLAB
x = imresize([1,2;3,4],[4,4],'bilinear')
ans =
1.0000 1.2500 1.7500 2.0000
1.5000 1.7500 2.2500 2.5000
2.5000 2.7500 3.2500 3.5000
3.0000 3.2500 3.7500 4.0000
Then I took the answers and resized them back to the original 2x2 size.
Python:
cv2.resize(x,(2,2), interpolation=cv2.INTER_LINEAR)
ans =
[[ 1.375, 2.125],
[ 2.875, 3.625]]
MATLAB:
imresize(x,[2,2],'bilinear')
ans =
1.5625 2.1875
2.8125 3.4375
They are clearly not the same, and when numbers are larger, the answers are a lot more different.
Any explanation or resources would be appreciated.
MATLAB's imresize
has anti-aliasing enabled by default:
>> imresize(x,[2,2],'bilinear')
ans =
1.5625 2.1875
2.8125 3.4375
>> imresize(x,[2,2],'bilinear','AntiAliasing',false)
ans =
1.3750 2.1250
2.8750 3.6250
This has tripped me up in the past, while trying to reproduce the results of imresize
using just interp2
.
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