Create a random image the size of a MODIS tile using Numpy and GDAL. N.B. this script creates tile 28 8.

gistfile1.py

from osgeo import gdal, gdal_array, osr
import numpy
from osgeo.gdalconst import GDT_Byte

xsize, ysize = 4800, 4800
a = numpy.random.randint(0, 100, (xsize, ysize)).astype(numpy.int8)

xmin, xmax = 100, 110.
ymin, ymax = 0, 10.


driver = gdal.GetDriverByName('GTiff')
out = driver.Create('/tmp/dummy.tif', a.shape[1], a.shape[0], 1, GDT_Byte)

srs=osr.SpatialReference()
srs.ImportFromEPSG(4326)

out.SetGeoTransform([xmin
                  , (xmax - xmin)/a.shape[0]
                  , 0
                  , ymin
                  , 0
                  , (ymax - ymin)/a.shape[1]])
                  
out.SetProjection(srs.ExportToWkt())

gdal_array.BandWriteArray(out.GetRasterBand(1), a)

out = None