c = Classify@trainedNet;
ClassifierMeasurements[c, testingData, "Accuracy"]
ClassifierMeasurements[c, testingData, "F1Score"]
ClassifierMeasurements[c, testingData, "ConfusionMatrixPlot"]
c /@ {"Accuracy", "FScore", "ConfusionMatrixPlot"} // TableForm

`ClassifierMeasurements::mlincfttp: Incompatible variable type (Image) and variable value (File[C:UserscnnDesktopimagestestcar0301.jpg])`.

cm = ClassifierMeasurements[trainedNet, testingData]
cm["Accuracy"]
cm["ConfusionMatrixPlot"]

ClassifierMeasurements::mlincfttp: Incompatible variable type (Image) and variable value (File[C:UserscnnDesktopimagestestcar0301.jpg]).

dir = SetDirectory["C:\Users\cnn\Desktop\images"];
loadFiles[dir_] :=
 Map[File[#] -> FileNameTake[#, {-2}] &,
  FileNames["*.jpg", dir, Infinity]];
 trainingData =
     loadFiles[FileNameJoin[{dir, "train"}]];
testingData =
     loadFiles[FileNameJoin[{dir, "test"}]];
    files = FileNames["*.JPG" | "*.JPEG",
      "C:\Users\cnn\Desktop\images\test", Infinity]
    testData = Import[#, ImageSize -> {224, 224}] & /@ files;

cm = ClassifierMeasurements[trainedNet, testData]
cm["Accuracy"]
cm["ConfusionMatrixPlot"]