I run Python processing algorithms externally, and I want to get the log output I see when I run it from the QGIS 3 GUI at the log tab as shown in the screenshot: 
[![enter image description here][1]][1]
I want to get the full grey log output when Result is returned only. How do I do that? 

An example follows:

    import os
    import sys
    import gdal
    gdal.UseExceptions()  # Allow GDAL to throw Python Exceptions
    
    from qgis.core import (
        QgsApplication,
        QgsProcessingFeedback,
        QgsMessageLog)
    
    from qgis.analysis import QgsNativeAlgorithms
    
    QgsApplication.setPrefixPath(os.path.join("C:", os.sep, "OSGeo4W64", "apps", "qgis"), True)
    qgs = QgsApplication([], False)
    qgs.initQgis()
    
    sys.path.append(os.path.join("C:", os.sep, "OSGeo4W64", "apps", "qgis", "python", "plugins"))
    import processing
    from processing.core.Processing import Processing
    
    Processing.initialize()
    QgsApplication.processingRegistry().addProvider(QgsNativeAlgorithms())
    
    
    def pca(input_raster_list):
    
        params = {
                    'input': input_raster_list,
                    'rescale': [0,0],
                    'percent': 99,
                    '-n': True,
                    '-f': False,
                    'output': 'C:\\Users\\...',
                    'GRASS_REGION_PARAMETER': None,
                    'GRASS_REGION_CELLSIZE_PARAMETER': 0
                    }
        feedback = QgsProcessingFeedback()
        res = processing.run("grass7:i.pca", params, feedback=feedback)
        print(res)
    
        return


  [1]: https://i.sstatic.net/MyrAK.png