[SciPy-User] Convert data to image and then image to numpy.ndarray
Robert Kern
robert.kern at gmail.com
Thu Apr 27 00:55:54 EDT 2017
On Wed, Apr 26, 2017 at 8:20 PM, Carlton Banks <noflaco at gmail.com> wrote:
>
> Is it possible to convert a data set stored as a numpy.ndarray -> plot
the data with a colormap , possibly cm.jet. -> and then store the image
pixels to a numpy.ndarray.
>
> The data array of the image should have the same shape of the data array
used to make the array.
> The image conversion is only used for getting a visual representation of
the data, and normalise it using the cm.jet.
> So I actually just interested in the RGB values of the colormap
normalised input data.
>
> IS this possible?
Sure, you can use matplotlib's colormap objects as functions to convert
arrays with values in the interval [0.0, 1.0] to arrays of colors.
[~]
|6> cm.viridis(np.linspace(0.0, 1.0, 5))
array([[ 0.267004, 0.004874, 0.329415, 1. ],
[ 0.229739, 0.322361, 0.545706, 1. ],
[ 0.127568, 0.566949, 0.550556, 1. ],
[ 0.369214, 0.788888, 0.382914, 1. ],
[ 0.993248, 0.906157, 0.143936, 1. ]])
[~]
|7> cm.viridis?
...
Call signature: cm.viridis(X, alpha=None, bytes=False)
Call docstring:
Parameters
----------
X : scalar, ndarray
The data value(s) to convert to RGBA.
For floats, X should be in the interval ``[0.0, 1.0]`` to
return the RGBA values ``X*100`` percent along the Colormap line.
For integers, X should be in the interval ``[0, Colormap.N)`` to
return RGBA values *indexed* from the Colormap with index ``X``.
alpha : float, None
Alpha must be a scalar between 0 and 1, or None.
bytes : bool
If False (default), the returned RGBA values will be floats in the
interval ``[0, 1]`` otherwise they will be uint8s in the interval
``[0, 255]``.
Returns
-------
Tuple of RGBA values if X is scalar, othewise an array of
RGBA values with a shape of ``X.shape + (4, )``.
--
Robert Kern
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