Me gustaría saber cómo cambiar un valor de píxel para el mapa de etiquetas.

Este es mi enfoque inicial. Desafortunadamente, los cambios no se reflejan en el lienzo.

X.volume.prototype.SetPixelLabelMap = function(i, j, k, value){
  this._labelmap._IJKVolume[k][j][i] = value;

  var color = this._labelmap._colortable._map.get(value);

  var changeRawData = function(rawdata, pos){
    for(var n = 0; n < 4; n++){
      rawdata[pos + n] = color[n + 1];
    }
  }

  var dim = this._dimensions;
  //in Z axis height is j width is i, the fast moving direction is the height
  if(this._labelmap._children[2]._children[k]){
    changeRawData(this._labelmap._children[2]._children[k]._texture._rawData, (dim[0]*i + j)*4);
  }

  //in Y axis height is k width is i
  if(this._labelmap._children[1]._children[j]){
    changeRawData(this._labelmap._children[1]._children[j]._texture._rawData, (dim[0]*i + k)*4);
  }
  
  if(this._labelmap._children[0]._children[i]){
    //in X axis height is j width is k
    changeRawData(this._labelmap._children[0]._children[i]._texture._rawData, (dim[2]*k + j)*4);
  }

}