code: def make_gt_area_histogram_plot(cocoEval, outDir):
      n_bins = 100
      areas = [ann["area"] for ann in cocoEval.cocoGt.anns.values()]
  
      # init figure
      figure_title = "gt annotation areas histogram plot"
      fig, ax = plt.subplots()
  
      # Set the number of bins
      ax.hist(np.sqrt(areas), bins=n_bins)
  
      # Add some text for labels, title and custom x-axis tick labels, etc.
      ax.set_xlabel("Squareroot Area")
      ax.set_ylabel("Number of annotations")
      ax.set_title(figure_title)
  
      # Save plot
      fig.tight_layout()
      fig.savefig(outDir + f"/{figure_title}.png")
      plt.close(fig)
  
file_path: mmdetection/tools/analysis_tools/coco_error_analysis.py
imports: import copy
  import os
  from argparse import ArgumentParser
  from multiprocessing import Pool
  import matplotlib.pyplot
  import numpy
  from pycocotools.coco import COCO
  from pycocotools.cocoeval import COCOeval
label_desc: Use image node_id 6 for calling a global function with example usage: make_gt_area_histogram_plot(cocoEval, outDir) without return types