import numpy
import rasterio
import subprocess

# Register GDAL format drivers and configuration options with a
# context manager.

with rasterio.drivers(CPL_DEBUG=True):

    # Read raster bands directly to Numpy arrays.
    #
    with rasterio.open('rasterio/tests/data/RGB.byte.tif') as src:
        b, g, r = src.read()

    # Combine arrays in place. Expecting that the sum will 
    # temporarily exceed the 8-bit integer range, initialize it as
    # 16-bit. Adding other arrays to it in-place converts those
    # arrays "up" and preserves the type of the total array.

    total = numpy.zeros(r.shape, dtype=rasterio.uint16)
    for band in r, g, b:
        total += band
    total /= 3

    # Write the product as a raster band to a new 8-bit file. For
    # keyword arguments, we start with the meta attributes of the
    # source file, but then change the band count to 1, set the
    # dtype to uint8, and specify LZW compression.

    kwargs = src.meta
    kwargs.update(
        dtype=rasterio.uint8,
        count=1,
        compress='lzw')

    with rasterio.open('example-total.tif', 'w', **kwargs) as dst:
        dst.write_band(1, total.astype(rasterio.uint8))

# At the end of the ``with rasterio.drivers()`` block, context
# manager exits and all drivers are de-registered.

# Dump out gdalinfo's report card and open the image.

info = subprocess.check_output(
    ['gdalinfo', '-stats', 'example-total.tif'])
print(info)
subprocess.call(['open', 'example-total.tif'])

with rasterio.drivers():

    with rasterio.open('rasterio/tests/data/RGB.byte.tif') as src:
        print(src.width, src.height)
        print(src.crs)
        print(src.affine)
        print(src.count)
        print(src.indexes)

# Output:
# (791, 718)
# {u'units': u'm', u'no_defs': True, u'ellps': u'WGS84', u'proj': u'utm', u'zone': 18}
# Affine(300.0379266750948, 0.0, 101985.0,
#        0.0, -300.041782729805, 2826915.0)
# 3
# [1, 2, 3]

with rasterio.drivers():

    rasterio.copy(
        'example-total.tif',
        'example-total.jpg', 
        driver='JPEG')

subprocess.call(['open', 'example-total.jpg'])