How to change the resolution of .tif raster file w

Question

For example, A .tiff file of 400*200 size, I can read it as a 2-D array(400 x 200) in python.

I want to change the tiff size to 200 x 100 or other ratio.

How to realize that in Python or GIS software(QGIS, ArcGIS et.al).

I know the resemble tool in ArcGIS can change the size of raster data. but the length-width ratio is fixed.

Example Diagram:

http://i12.tietuku.com/b0841a1ceb25729a.png

Answer 1

With R you can do things like

library(raster)
r <- raster('file.tif')
a <- aggregate(r, c(2,3))