down sample nearest method

I want to down sampling a image for this i use the function: imresize(im,0.5,'nearest'). But i don't understand how the nearest interpolation work in this case, i undestand in upsampling but not in downsampling?

Thanks for your answer

Answer 1

[Sourav Bairagya]

The command 'imresize(im,0.5,'nearest')' will first find out the query points i.e. it will map the output image cordinates to the input image coordinate space using the 'scale' provided in the input argument of 'imresize'. Then, using the selected 'method' in the input argument of the function, it will compute the values at those query points. Thus, downsampling is performed.

[Gamliel Roos]

Thanks for your answer but how this 'method' (nearest) work in down sampling?

[Sourav Bairagya]

It will copy the nearest pixel value at the query point. First, it will search horizontally which pixels are nearest to that point. Then, it will search vertically the nearest one among those pixels and copy that value to the desired location.