satsense.image¶
Methods for loading images.
- class
satsense.image.Image(filename, satellite, band='rgb', normalization_parameters=None, block=None, cached=None)[source]¶Bases:
objectImage class that provides a unified interface to satellite images.
Under the hood rasterio is used, so any format supported by rasterio can be used.
Parameters:
- filename (str) – The name of the image
- satellite (str) – The name of the satelite (i.e. worldview3, quickbird etc.)
- band (str) – The band for the grayscale image, or ‘rgb’. The default is ‘rgb’
- normalization_parameters (dict or boolean, optional) –
if False no normalization is done. if None the default normalization will be applied (cumulative with 2, 98 percentiles)
f a Dictionary that describes the normalization parameters The following keys can be supplied:
- technique: string
- The technique to use, can be ‘cumulative’ (default), ‘meanstd’ or ‘minmax’
- percentiles: list[int]
- The percentiles to use (exactly 2) if technique is cumulative, default is [2, 98]
- numstds: float
- Number of standard deviations to use if technique is meanstd
- block (tuple or rasterio.windows.Window, optional) – The part of the image read defined in a rasterio compatible way, e.g. two tuples or a rasterio.windows.Window object
- cached (array-like or boolean, optional) – If True bands and base images are cached in memory if an array a band or base image is cached if its name is in the array
Examples
Load an image and inspect the shape and bands
from satsense import Image >>> image = Image(‘test/data/source/section_2_sentinel.tif’, ‘quickbird’) >>> image.shape (152, 155)
>>> image.bands {'blue': 0, 'green': 1, 'red': 2, 'nir-1': 3}>>> image.crs CRS({'init': 'epsg:32643'})See also
itypes= {'canny_edge': <function get_canny_edge_image>, 'gray_ubyte': <function get_gray_ubyte_image>, 'grayscale': <function get_grayscale_image>, 'ndsi': functools.partial(<function ndxi_image>, ndxi_type='ndsi'), 'ndwi': functools.partial(<function ndxi_image>, ndxi_type='ndwi'), 'nir_ndvi': functools.partial(<function ndxi_image>, ndxi_type='nir_ndvi'), 'rb_ndvi': functools.partial(<function ndxi_image>, ndxi_type='rb_ndvi'), 'rg_ndvi': functools.partial(<function ndxi_image>, ndxi_type='rg_ndvi'), 'rgb': <function get_rgb_image>, 'texton_descriptors': <function get_texton_descriptors>, 'wvsi': functools.partial(<function ndxi_image>, ndxi_type='wvsi')}¶
- classmethod
register(itype, function)[source]¶Register a new image type.
Parameters:
- itype (str) – (internal) name of the image type
- function – Function definition that should take a single Image parameter and return a numpy.ndarray or numpy.ma.masked_array
See also
ufunc: get_gray_ubyte_image ufunc: get_grayscale_image ufunc: get_rgb_image
copy_block(block)[source]¶Create a subset of Image.
Parameters: block (tuple or rasterio.windows.Window) – The part of the image to read defined in a rasterio compatible way, e.g. two tuples or a rasterio.windows.Window object Returns: subsetted image Return type: image.Image
__getitem__(itype)[source]¶Get image of a type registered using the register method. The following itypes are available to facilitate creating new features: - ‘rgb’ - ‘grayscale’ - ‘gray_ubyte’
Parameters: itype (str) – The name of the image type to retrieve Returns: out – The image of the supplied type Return type: numpy.ndarray or numpy.ma.masked_array Examples
Get the rgb image >>> image[‘rgb’].shape (152, 155, 3) >>> image[‘gray_ubyte’].dtype dtype(‘uint8’)
precompute_normalization(*bands)[source]¶Precompute the normalization of the image
Normalization is done using the normalization_parameters supplied during class instantiation. Normalization parameters are computed automatically for all bands when required, but doing it explicitly can save some time, e.g. if there are more bands in the image than needed.
Parameters: *bands (list[str] or None) – The list of bands to normalize, if None all bands will be normalized Raises: ValueError: – When trying to compute the normalization on a partial image, as created by using the copy_block method. See also
Image()
func: _normalize Get normalization limits for band(s).
shape¶Provide shape attribute.
crs¶Provide crs attribute.
transform¶Provide transform attribute.
satsense.image.get_rgb_image(image: satsense.image.Image)[source]¶Convert the image to rgb format.
Parameters: image (image.Image) – The image to calculate the rgb image from Returns: The image converted to rgb Return type: numpy.ndarray
satsense.image.get_grayscale_image(image: satsense.image.Image)[source]¶Convert the image to grayscale.
Parameters: image (image.Image) – The image to calculate the grayscale image from Returns: The image converted to grayscale in 0 - 1 range Return type: numpy.ndarray See also
skimage.color.rgb2gray()- Used to convert rgb image to grayscale
satsense.image.get_gray_ubyte_image(image: satsense.image.Image)[source]¶Convert image in 0 - 1 scale format to ubyte 0 - 255 format.
Parameters: image (image.Image) – The image to calculate the grayscale image from Returns: The image converted to grayscale Return type: numpy.ndarray See also
skimage.img_as_ubyte()- Used to convert the image to ubyte
- class
satsense.image.FeatureVector(feature, vector, crs=None, transform=None)[source]¶Bases:
objectClass to store a feature vector in.
Parameters:
- feature (satsense.feature.Feature) – The feature to store
- vector (array-like) – The data of the computed feature
- crs – The coordinate reference system for the data
- transform (Affine) – The affine transformation for the data
get_filename(window, prefix='', extension='nc')[source]¶Construct filename from input parameters.
Parameters: Returns: Return type: