Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

"colour.dominant_wavelength" definition seems to struggle with precise spectral locus CMF xy values?

See original GitHub issue

Issue Description

CMFS_1931 = colour.MSDS_CMFS["CIE 1931 2 Degree Standard Observer"]

CMFS_1931_xy = colour.XYZ_to_xy(CMFS_1931.values)
whitepoint = numpy.asarray([0.3101, 0.3163])

discard, locus_1931_samples_xy, discard = \
    colour.dominant_wavelength(
        CMFS_1931_xy,
        whitepoint,
        cmfs=CMFS_1931,
)

/usr/local/lib/python3.7/dist-packages/colour/algebra/geometry.py:326: RuntimeWarning: invalid value encountered in true_divide
  u_a = numerator_a / denominator
/usr/local/lib/python3.7/dist-packages/colour/algebra/geometry.py:327: RuntimeWarning: divide by zero encountered in true_divide
  u_b = numerator_b / denominator
/usr/local/lib/python3.7/dist-packages/colour/algebra/geometry.py:327: RuntimeWarning: invalid value encountered in true_divide
  u_b = numerator_b / denominator
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-40-2288142fce39> in <module>()
     10         CMFS_1931_xy,
     11         whitepoint,
---> 12         cmfs=CMFS_1931,
     14 )

3 frames
/usr/local/lib/python3.7/dist-packages/colour/colorimetry/dominant.py in dominant_wavelength(xy, xy_n, cmfs, inverse)
    194     xy_s = XYZ_to_xy(cmfs.values)
    195 
--> 196     i_wl, xy_wl = closest_spectral_locus_wavelength(xy, xy_n, xy_s, inverse)
    197     xy_cwl = xy_wl
    198     wl = cmfs.wavelengths[i_wl]

/usr/local/lib/python3.7/dist-packages/colour/colorimetry/dominant.py in closest_spectral_locus_wavelength(xy, xy_n, xy_s, inverse)
    117     i_wl = np.argmin(scipy.spatial.distance.cdist(xy_wl, xy_s), axis=-1)
    118 
--> 119     i_wl = np.reshape(i_wl, xy.shape[0:-1])
    120     xy_wl = np.reshape(xy_wl, xy.shape)
    121 

<__array_function__ internals> in reshape(*args, **kwargs)

/usr/local/lib/python3.7/dist-packages/numpy/core/fromnumeric.py in reshape(a, newshape, order)
    297            [5, 6]])
    298     """
--> 299     return _wrapfunc(a, 'reshape', newshape, order=order)
    300 
    301 

/usr/local/lib/python3.7/dist-packages/numpy/core/fromnumeric.py in _wrapfunc(obj, method, *args, **kwds)
     56 
     57     try:
---> 58         return bound(*args, **kwds)
     59     except TypeError:
     60         # A TypeError occurs if the object does have such a method in its

ValueError: cannot reshape array of size 6225 into shape (471,)

Issue Analytics

State:
Created a year ago
Comments:18 (18 by maintainers)

Top GitHub Comments

1reaction

KelSolaarcommented, Feb 21, 2022

Nah, one liner change.

1reaction

sobotkacommented, Feb 20, 2022

I arrived at one via Shapely. Not sure if it is relevant or if it could be viable for Colour, but it seems to work pretty well. Essentially create a Shapely polygon from the CMFS, then use the intersection to calculate.

spectral_locus_polygon = shapely.geometry.Polygon(
    CMFS_xyY[:, 0:2]
)

spectral_intersections = []
for line in xy_lines.geoms:
    intersection = spectral_locus_polygon.intersection(line)
    spectral_intersections.append(intersection)

Top Results From Across the Web

Dominant wavelength - Wikipedia

In color science, the dominant wavelength is a method of characterizing a color's hue. Along with purity, it makes up one half of...

Chromaticity Diagram - an overview | ScienceDirect Topics

The spectrum locus is the set of chromaticity coordinates of pure monochromatic (single-wavelength) lights. All realizable colors fall within the spectrum ...

LED Dominant vs Peak Wavelength - What is Going On?

My personal view is that dominant wavelength is a marketing-led simplification of colour specification. We go from CIE XYZ tristimulus (3 ...

colour.dominant_wavelength — Colour 0.3.14 documentation

Returns the dominant wavelength λd for given colour stimulus xy and the related xywl first and xycw second intersection coordinates with the spectral...

2.4 COLORIMETRY - 2.Concepts - Language of Light

The dominant wavelength (DW) of a colour is the wavelength of the spectrum colour whose chromaticity is on the same straight line as...