ColorTracker: A wrapper for the CurveTool, which allows you to analyze color change over time of an input, and apply that data to a grade in matchmove or stabilize mode around a specified reference frame. Because I am bad at remembering math.

ColorTracker.nk

Group {
name ColorTracker
addUserKnob {20 ColorTracker}
addUserKnob {26 instructions_text l <b>Instructions: T "1). Stabilize your plate around the area you want to track\n2). Crop your plate to just the area you want to analyze\n4). Press Track Color to analyze the footage\n5). Create a matchmove or stabilize grade, and specify your reference frame\n6). You can scale the curve around a specified pivot value on the grade node \n      using the color_pivot and color_mult knobs in the ColorTrack tab"}
addUserKnob {26 ""}
addUserKnob {26 label_trackcolor l "<b>Track Color" T " "}
addUserKnob {41 track_color l "Track Color" t "This button will track the color change over the specified framerange and put the data into the intensitydata knob." T CurveTool.go}
addUserKnob {41 intensitydata T CurveTool.intensitydata}
addUserKnob {26 ""}
addUserKnob {26 label_apply_color_track l "<b>Apply Track" T " "}
addUserKnob {3 reference_frame l "reference frame" t "On the specified frame, the calculated color change will have no effect."}
reference_frame 1001
addUserKnob {4 mode l Mode t "If using this node to apply the color transform, choose whether to matchmove or stabilize the sampled color." M {Matchmove Stabilize "" "" "" ""}}
addUserKnob {6 enable_expression_links t "If this is enabled, the grade node will be expression linked to the color track node. Otherwise the keyframes will be baked." -STARTLINE}
enable_expression_links true
addUserKnob {22 create_linked_grade l "Create Linked Grade" t "Creates a grade expression linked to this node. Useful if you need to link the same color transform to many places in your script. " T "## Create Linked Grade\n\nn = nuke.thisNode()\n\nnuke.root().begin()\n\ngrade_node = nuke.createNode('Grade')\ngrade_node.setName('\{0\}_APPLY'.format(n.fullName()))\ngrade_node.addKnob(nuke.Tab_Knob('ColorTrack'))\ngrade_node.addKnob(nuke.Int_Knob('reference_frame', 'reference frame'))\ngrade_node\['reference_frame'].setValue(int(n\['reference_frame'].value()))\ngrade_node.addKnob(nuke.Boolean_Knob('stabilize', 'stabilize'))\ngrade_node\['stabilize'].clearFlag(nuke.STARTLINE)\ngrade_node\['stabilize'].setValue(n\['mode'].getValue())\n\ngrade_node.addKnob(nuke.AColor_Knob('intensitydata', 'intensitydata'))\ngrade_node.addKnob(nuke.AColor_Knob('color_pivot', 'color_pivot'))\ngrade_node.addKnob(nuke.AColor_Knob('color_mult', 'color_mult'))\ngrade_node\['color_pivot'].setValue(\[1,1,1,1])\ngrade_node\['color_mult'].setValue(\[1,1,1,1])\n\n# Set intensity data: expression link if enable_expression_links is set, otherwise copy the animation curve\nintensity_data_knob = grade_node\['intensitydata']\nintensity_data_knob_src = n\['intensitydata']\nif n\['enable_expression_links'].getValue():\n\tintensity_data_knob.setExpression('parent.\{0\}.intensitydata'.format(n.fullName()))\nelse:\n\t# Copy the animation curves from the Color Track node\n\tintensity_data_knob.setAnimated()\n\tfor i, k in enumerate(intensity_data_knob.animations()):\n\t\tif intensity_data_knob_src.isAnimated():\n\t\t\tk.addKey(intensity_data_knob_src.animation(i).keys())\n\n\n\nexprstring = 'stabilize ? 1/(((intensitydata / intensitydata(reference_frame))-color_pivot)*color_mult+color_pivot) : ((intensitydata / intensitydata(reference_frame))-color_pivot)*color_mult+color_pivot'\ngrade_node\['white'].setValue(1, 1) # Split the color knob\nfor i in xrange(4):\n    grade_node\['white'].setExpression(exprstring, i)" +STARTLINE}
}
Input {
 inputs 0
 name Input
 xpos 400
 ypos -729
}
CurveTool {
 ROI {0 0 {width} {height}}
 autocropdata {160 120 480 360}
 intensitydata 1
 maxlumapixdata {140 385}
 minlumapixdata {186 -390}
 name CurveTool
 xpos 400
 ypos -490
}
Output {
 name Output1
 xpos 400
 ypos -226
}
end_group

Hey is any way to hide the colortracker tab in the grade node that's created?

Sure, just modify the python code that creates the grade and simplify it however you like. Simplest case would be to just copy the animation curves from the curvetool. If you want to explain in more detail what your use-case and motivation is I might be interested in helping

Thanks for responding. I was trying to figure that out but Im pretty garbage at python. I wanted to see if I could do it but I can't figure it out.