python - <<'PY'
import cv2,numpy as np
im=cv2.imread('/workspace/input/charts/HH-1041_chart.tif',-1);g=cv2.cvtColor((im/257).astype('uint8'),cv2.COLOR_BGR2GRAY);ed=cv2.Canny(g,40,100);cs,_=cv2.findContours(ed,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)
print([cv2.boundingRect(c) for c in cs if 70<cv2.boundingRect(c)[2]<110 and 70<cv2.boundingRect(c)[3]<110 and cv2.contourArea(c)>3000])
PY
head -160 /workspace/scratch/pdf_api.txt