from 256 by 256 pixels to 128 by 128

[Nikolai_0801]

I want to delete some noise and small details from mu binary image data file.
Suppose I have a 256x256 image file (scientific data). How to decrease resolution down to 128x128 or 64x64 pixels ? What is the difference if one takes the spatial Furier tyransform for data with high resolution and filter out "high components" ?