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# image sampling and its implementation in opencv

I have a set of image pairs, i.e., {A, A’}, {B, B’}, {C,C’} etc.

Given an image A, for instance, 256*256, are there any sampling mechanisms to generate a small image, i.e., 128*128, that can capture the global contexts of original images.

At the same time, I would like to keep track information of those sampled pixels. For instance, if pixel[I,J] in A is selected, I need to track it because I need to select the same pixel of A’.

In other words, I need to generate a set of smaller image pairs based on these large image pairs. The sampling mechanism, however, is based on A, B, C, etc.

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## Comments

hey, i've read this for 3 times, still no idea, what you're actually asking.

( 2017-02-22 12:26:51 -0600 )edit

Use a nearest neighbor algorithm for resizing and store in another matrix the original coordinate. For instance: pixel a at coordinate (100,100), when downsampling by a factor of 2, the corresponding pixel is a' at coordinate (50,50). So in another matrix, in the coordinate (50,50) you will store (100,100).

( 2017-02-23 04:39:43 -0600 )edit

## 1 answer

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Well if you are using python, you can use "cv2.resize()"

subA = cv2.resize(A, (128,128), interpolation = cv2.INTER_AREA)

subA' = cv2.resize(A', (128,128), interpolation = cv2.INTER_AREA)

if both A,A' are same in dimension then both sub-sampled image will have same pixel operation on it

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Asked: 2017-02-22 11:40:32 -0600

Seen: 3,328 times

Last updated: Feb 22 '17