ColorMapToLUT XML
web-test/Python/Utilities/ColorMapToLUT_XML
Description¶
Generate a VTK colormap from an XML description of a colormap.
A cone is rendered to demonstrate the resultant colormap.
C++ and Python functions can also be generated which implement the colormap. You can copy/paste these directly into your code. Or they can replace the existing function in:
This program was inspired by this discussion: Replacement default color map and background palette, and, the Fast colormap from this discussion is used as test data here.
A good initial source for color maps is: SciVisColor -- this will provide you with plenty of XML examples.
Note:
- The XML parser is lxml
- Currently, the parsing only works for XML colormaps with no Section key.
Further information:
- VTK Examples - Some ColorMap to LookupTable tools
- Color maps and transfer functions
- How to export ParaView colormap into a format that could be read by matplotlib
- How to export ParaView colormap into a format that could be read by matplotlib?
- Color map advice and resources
- ParaView Default Colormaps will provide you with lots of colormaps.
Other languages
See (PythonicAPI)
Question
If you have a question about this example, please use the VTK Discourse Forum
Code¶
ColorMapToLUT_XML.py
#!/usr/bin/env python3
import sys
from pathlib import Path
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from lxml import etree
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkFiltersCore import vtkElevationFilter
from vtkmodules.vtkFiltersSources import vtkConeSource, vtkSphereSource
from vtkmodules.vtkInteractionStyle import vtkInteractorStyleTrackballCamera
from vtkmodules.vtkRenderingCore import (
vtkActor,
vtkPolyDataMapper,
vtkRenderWindow,
vtkRenderWindowInteractor,
vtkRenderer
)
from vtkmodules.vtkRenderingCore import (
vtkDiscretizableColorTransferFunction,
)
def get_program_parameters(argv):
import argparse
description = 'Take an XML description of a colormap and convert it to a VTK colormap.'
epilogue = '''
A color transfer function in C++ or Python can be optionally generated.
'''
parser = argparse.ArgumentParser(description=description, epilog=epilogue,
formatter_class=argparse.RawDescriptionHelpFormatter)
parser.add_argument('file_name', help='The path to the XML file e.g Fast.xml.')
parser.add_argument('-d', action='store_true', dest='discretize', help='Discretize the colormap.')
parser.add_argument('-s', dest='size', default=None, type=int,
help='Specify the size of the colormap.')
parser.add_argument('-g', dest='generate_function', default=None,
help='Generate code for the color transfer function,'
' specify the desired language one of: Cxx, Python.')
args = parser.parse_args()
return args.file_name, args.discretize, args.size, args.generate_function
def main(file_name, discretize, table_size, generate_function):
if file_name:
fn_path = Path(file_name)
if not fn_path.suffix:
fn_path = fn_path.with_suffix(".xml")
if not fn_path.is_file():
print('Unable to find: ', fn_path)
return
else:
print('Please enter a path to the XML file.')
return
parameters = parse_xml(fn_path)
if generate_function is not None:
generate_function = generate_function.lower()
available_languages = {k.lower(): k for k in ['Cxx', 'Python']}
available_languages.update({'cpp': 'Cxx', 'c++': 'Cxx', 'py': 'Python'})
if generate_function not in available_languages:
print(f'The language: {generate_function} is not available.')
tmp = ', '.join(sorted([lang for lang in set(available_languages.values())]))
print(f'Choose one of these: {tmp}.')
return
else:
language = available_languages[generate_function]
else:
language = None
# There is just one entry in the parameters dict.
colormap_name = list(parameters.keys())[0]
ctf = make_ctf(parameters[colormap_name], discretize, table_size)
if language is not None and language in ['Cxx', 'Python']:
if language == 'Python':
generate_ctf_python(parameters[colormap_name], discretize, table_size)
else:
generate_ctf_cpp(parameters[colormap_name], discretize, table_size)
colors = vtkNamedColors()
colors.SetColor('ParaViewBkg', 82, 87, 110, 255)
sphere = vtkSphereSource()
sphere.SetThetaResolution(64)
sphere.SetPhiResolution(32)
cone = vtkConeSource()
cone.SetResolution(6)
cone.SetDirection(0, 1, 0)
cone.SetHeight(1)
cone.Update()
# bounds = sphere.GetOutput().GetBounds()
bounds = cone.GetOutput().GetBounds()
elevation_filter = vtkElevationFilter()
elevation_filter.SetLowPoint(0, bounds[2], 0)
elevation_filter.SetHighPoint(0, bounds[3], 0)
# elevation_filter.SetInputConnection(sphere.GetOutputPort())
elevation_filter.SetInputConnection(cone.GetOutputPort())
mapper = vtkPolyDataMapper()
mapper.SetInputConnection(elevation_filter.GetOutputPort())
mapper.SetLookupTable(ctf)
mapper.SetColorModeToMapScalars()
mapper.InterpolateScalarsBeforeMappingOn()
actor = vtkActor()
actor.SetMapper(mapper)
# Visualize
ren = vtkRenderer()
ren_win = vtkRenderWindow()
ren_win.AddRenderer(ren)
iren = vtkRenderWindowInteractor()
iren.SetRenderWindow(ren_win)
style = vtkInteractorStyleTrackballCamera()
iren.SetInteractorStyle(style)
ren.AddActor(actor)
ren.SetBackground(colors.GetColor3d('ParaViewBkg'))
ren_win.SetSize(640, 480)
ren_win.SetWindowName('ColorMapToLUT_XML')
ren_win.Render()
iren.Start()
def parse_xml(fn_path):
"""
Parse the XML file of a colormap.
Check out: https://sciviscolor.org/colormaps/ for some good XML files.
:param fn_path: The path to the XML file.
:return: The parameters for the color map.
"""
with open(fn_path) as data_file:
xml_doc = etree.parse(data_file)
def extract(d):
"""
Pull out the data we need.
:param d: The parsed XML data.
:return: The extracted data.
"""
color_map_details = dict()
data_values = list()
color_values = list()
opacity_values = list()
nan = None
above = None
below = None
if d is not None:
color_map_details = dict(d.attrib)
if 'space' in color_map_details:
# Some XML files use space instead of interpolation space.
if color_map_details['space'].lower() not in ['rgb', 'hsv']:
color_map_details['interpolationspace'] = color_map_details['space']
# Assume RGB
color_map_details['space'] = 'RGB'
for pt in d.findall('.//Point'):
# "o" is opacity it (along with "cms" and "isMoT") are ignored.
# "x" is the scalar value associated with the color (specified by "r", "g", and "b").
data_values.append(pt.attrib['x'])
color_values.append((pt.attrib['r'], pt.attrib['g'], pt.attrib['b']))
if pt.attrib['o']:
opacity_values.append(pt.attrib['o'])
val = d.find('.//NaN')
if val is not None:
nan = (val.attrib['r'], val.attrib['g'], val.attrib['b'])
val = d.find('.//Above')
if val is not None:
above = (val.attrib['r'], val.attrib['g'], val.attrib['b'])
val = d.find('.//Below')
if val is not None:
below = (val.attrib['r'], val.attrib['g'], val.attrib['b'])
return {'color_map_details': color_map_details, 'data_values': data_values,
'color_values': color_values, 'opacity_values': opacity_values, 'NaN': nan, 'Above': above,
'Below': below}
s = xml_doc.getroot().find('ColorMap')
if s is None:
sys.exit('The attribute "ColorMap" is not found.')
res = dict()
parameters = extract(s)
parameters['path'] = fn_path.name
cm_name = parameters['color_map_details']['name']
# Do some checks.
if cm_name is not None:
if len(parameters['data_values']) != len(parameters['color_values']):
sys.exit(f'{parameters["path"]}: The data values length must be the same as colors.')
if len(parameters['opacity_values']) > 0:
if len(parameters['opacity_values']) != len(parameters['color_values']):
sys.exit(f'{parameters["path"]}: The opacity values length must be the same as colors.')
res[cm_name] = parameters
return res
def make_ctf(parameters, discretize, table_size=None):
"""
Generate the discretizable color transfer function
:param parameters: The parameters.
:param discretize: True if the values are to be mapped after discretization.
:param table_size: The table size.
:return: The discretizable color transfer function.
"""
ctf = vtkDiscretizableColorTransferFunction()
interp_space = parameters['color_map_details'].get('interpolationspace', None)
if interp_space:
interp_space = interp_space.lower()
if interp_space == 'hsv':
ctf.SetColorSpaceToHSV()
elif interp_space == 'lab':
ctf.SetColorSpaceToLab()
elif interp_space == 'cielab':
ctf.SetColorSpaceToLab()
elif interp_space == 'ciede2000':
ctf.SetColorSpaceToLabCIEDE2000()
elif interp_space == 'diverging':
ctf.SetColorSpaceToDiverging()
elif interp_space == 'step':
ctf.SetColorSpaceToStep()
else:
ctf.SetColorSpaceToRGB()
else:
ctf.SetColorSpaceToRGB()
scale = parameters['color_map_details'].get('interpolationtype', None)
if scale:
scale = scale.lower()
if scale == 'log10':
ctf.SetScaleToLog10()
else:
ctf.SetScaleToLinear()
else:
ctf.SetScaleToLinear()
if parameters['NaN'] is not None:
color = list(map(float, parameters['NaN']))
ctf.SetNanColor(*color)
if parameters['Above'] is not None:
color = list(map(float, parameters['Above']))
ctf.SetAboveRangeColor(*color)
ctf.UseAboveRangeColorOn()
if parameters['Below'] is not None:
color = list(map(float, parameters['Below']))
ctf.SetBelowRangeColor(*color)
ctf.UseBelowRangeColorOn()
space = parameters['color_map_details'].get('space', None)
if space:
space = space.lower()
for i in range(0, len(parameters['data_values'])):
color = list(map(float, parameters['color_values'][i]))
idx = float(parameters['data_values'][i])
if space == 'hsv':
ctf.AddHSVPoint(idx, *color)
else:
ctf.AddRGBPoint(idx, *color)
if table_size is not None:
ctf.SetNumberOfValues(table_size)
else:
ctf.SetNumberOfValues(len(parameters["data_values"]))
if discretize:
ctf.DiscretizeOn()
else:
ctf.DiscretizeOff()
return ctf
def generate_ctf_python(parameters, discretize, table_size=None):
"""
Generate a function for the ctf.
:param parameters: The parameters.
:param discretize: True if the values are to be mapped after discretization.
:param table_size: The table size.
:return: The discretizable color transfer function.
"""
indent = ' ' * 4
comment = f'{indent}#'
if 'name' in parameters['color_map_details']:
comment += f' name: {parameters["color_map_details"]["name"]},'
if 'creator' in parameters['color_map_details']:
comment += f' creator: {parameters["color_map_details"]["creator"]}'
if 'interpolationspace' in parameters['color_map_details']:
comment += f'\n{indent}# interpolationspace: {parameters["color_map_details"]["interpolationspace"]},'
if 'interpolationtype' in parameters['color_map_details']:
comment += f' interpolationtype: {parameters["color_map_details"]["interpolationtype"]},'
if 'space' in parameters['color_map_details']:
comment += f' space: {parameters["color_map_details"]["space"]}'
comment += f'\n{indent}# file name: {parameters["path"]}\n'
s = ['', f'def get_ctf():', comment, f'{indent}ctf = vtkDiscretizableColorTransferFunction()', '']
interp_space = parameters['color_map_details'].get('interpolationspace', None)
if interp_space:
interp_space = interp_space.lower()
if interp_space == 'hsv':
s.append(f'{indent}ctf.SetColorSpaceToHSV()')
elif interp_space == 'lab':
s.append(f'{indent}ctf.SetColorSpaceToLab()')
elif interp_space == 'cielab':
s.append(f'{indent}ctf.SetColorSpaceToLab()')
elif interp_space == 'ciede2000':
s.append(f'{indent}ctf.SetColorSpaceToLabCIEDE2000()')
elif interp_space == 'diverging':
s.append(f'{indent}ctf.SetColorSpaceToDiverging()')
elif interp_space == 'step':
s.append(f'{indent}ctf.SetColorSpaceToStep()')
else:
s.append(f'{indent}ctf.SetColorSpaceToRGB()')
else:
s.append(f'{indent}ctf.SetColorSpaceToRGB()')
scale = parameters['color_map_details'].get('interpolationtype', None)
if scale:
scale = scale.lower()
if scale == 'log10':
s.append(f'{indent}ctf.SetScaleToLog10()')
else:
s.append(f'{indent}ctf.SetScaleToLinear()')
else:
s.append(f'{indent}ctf.SetScaleToLinear()')
s.append('')
if parameters['NaN'] is not None:
color = ', '.join(parameters['NaN'])
s.append(f'{indent}ctf.SetNanColor({color})')
if parameters['Above'] is not None:
color = ', '.join(parameters['Above'])
s.append(f'{indent}ctf.SetAboveRangeColor({color})')
s.append(f'{indent}ctf.UseAboveRangeColorOn()')
if parameters['Below'] is not None:
color = ', '.join(parameters['Below'])
s.append(f'{indent}ctf.SetBelowRangeColor({color})')
s.append(f'{indent}ctf.UseBelowRangeColorOn()')
s.append('')
space = parameters['color_map_details'].get('space', None)
if space:
space = space.lower()
for i in range(0, len(parameters['data_values'])):
color = ', '.join(parameters['color_values'][i])
idx = parameters['data_values'][i]
if space == 'hsv':
s.append(f'{indent}ctf.AddHSVPoint({idx}, {color})')
else:
s.append(f'{indent}ctf.AddRGBPoint({idx}, {color})')
s.append('')
if table_size is not None:
s.append(f'{indent}ctf.SetNumberOfValues({table_size})')
else:
s.append(f'{indent}ctf.SetNumberOfValues({len(parameters["data_values"])})')
if discretize:
s.append(f'{indent}ctf.DiscretizeOn()')
else:
s.append(f'{indent}ctf.DiscretizeOff()')
s.append('')
s.append(f'{indent}return ctf')
s.append('')
print('\n'.join(s))
def generate_ctf_cpp(parameters, discretize, table_size=None):
"""
Generate a function for the ctf.
:param parameters: The parameters.
:param discretize: True if the values are to be mapped after discretization.
:param table_size: The table size.
:return: The discretizable color transfer function.
"""
indent = ' ' * 2
comment = f'{indent}//'
if 'name' in parameters['color_map_details']:
comment += f' name: {parameters["color_map_details"]["name"]},'
if 'creator' in parameters['color_map_details']:
comment += f' creator: {parameters["color_map_details"]["creator"]}'
if 'interpolationspace' in parameters['color_map_details']:
comment += f'\n{indent}// interpolationspace: {parameters["color_map_details"]["interpolationspace"]},'
if 'interpolationtype' in parameters['color_map_details']:
comment += f' interpolationtype: {parameters["color_map_details"]["interpolationtype"]},'
if 'space' in parameters['color_map_details']:
comment += f' space: {parameters["color_map_details"]["space"]}'
comment += f'\n{indent}// file name: {parameters["path"]}\n'
s = ['', f'vtkNew<vtkDiscretizableColorTransferFunction> GetCTF()', '{', comment,
f'{indent}vtkNew<vtkDiscretizableColorTransferFunction> ctf;', '']
interp_space = parameters['color_map_details'].get('interpolationspace', None)
if interp_space:
interp_space = interp_space.lower()
if interp_space == 'hsv':
s.append(f'{indent}ctf->SetColorSpaceToHSV();')
elif interp_space == 'lab':
s.append(f'{indent}ctf->SetColorSpaceToLab();')
elif interp_space == 'cielab':
s.append(f'{indent}ctf->SetColorSpaceToLab();')
elif interp_space == 'ciede2000':
s.append(f'{indent}ctf->SetColorSpaceToLabCIEDE2000();')
elif interp_space == 'diverging':
s.append(f'{indent}ctf->SetColorSpaceToDiverging();')
elif interp_space == 'step':
s.append(f'{indent}ctf->SetColorSpaceToStep();')
else:
s.append(f'{indent}ctf->SetColorSpaceToRGB();')
else:
s.append(f'{indent}ctf->SetColorSpaceToRGB();')
scale = parameters['color_map_details'].get('interpolationtype', None)
if scale:
scale = scale.lower()
if scale == 'log10':
s.append(f'{indent}ctf->SetScaleToLog10();')
else:
s.append(f'{indent}ctf->SetScaleToLinear();')
else:
s.append(f'{indent}ctf->SetScaleToLinear();')
s.append('')
if parameters['NaN'] is not None:
color = ', '.join(parameters['NaN'])
s.append(f'{indent}ctf->SetNanColor({color});')
if parameters['Above'] is not None:
color = ', '.join(parameters['Above'])
s.append(f'{indent}ctf->SetAboveRangeColor({color});')
s.append(f'{indent}ctf->UseAboveRangeColorOn();')
if parameters['Below'] is not None:
color = ', '.join(parameters['Below'])
s.append(f'{indent}ctf->SetBelowRangeColor({color});')
s.append(f'{indent}ctf->UseBelowRangeColorOn();')
s.append('')
space = parameters['color_map_details'].get('space', None)
if space:
space = space.lower()
for i in range(0, len(parameters['data_values'])):
color = ', '.join(parameters['color_values'][i])
idx = parameters['data_values'][i]
if space == 'hsv':
s.append(f'{indent}ctf->AddHSVPoint({idx}, {color});')
else:
s.append(f'{indent}ctf->AddRGBPoint({idx}, {color});')
s.append('')
if table_size is not None:
s.append(f'{indent}ctf->SetNumberOfValues({table_size});')
else:
s.append(f'{indent}ctf->SetNumberOfValues({len(parameters["data_values"])});')
if discretize:
s.append(f'{indent}ctf->DiscretizeOn();')
else:
s.append(f'{indent}ctf->DiscretizeOff();')
s.append('')
s.append(f'{indent}return ctf;')
s.append('}')
s.append('')
print('\n'.join(s))
if __name__ == '__main__':
file, discretise, size, generate = get_program_parameters(sys.argv)
main(file, discretise, size, generate)