Lecture 4.5 - Mini Project # 2 - Identifying Contours by Shape.ipynb

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   "source": [
    "## Mini Project 2 - Identifiy Contours by Shape"
   ]
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    "import numpy as np\n",
    "import cv2\n",
    "\n",
    "# Load and then gray scale image\n",
    "\n",
    "image = cv2.imread('images/someshapes.jpg')\n",
    "gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)\n",
    "\n",
    "cv2.imshow('Identifying Shapes',image)\n",
    "cv2.waitKey(0)\n",
    "\n",
    "ret, thresh = cv2.threshold(gray, 127, 255, 1)\n",
    "\n",
    "# Extract Contours\n",
    "contours, hierarchy = cv2.findContours(thresh.copy(), cv2.RETR_LIST, cv2.CHAIN_APPROX_NONE)\n",
    "\n",
    "for cnt in contours:\n",
    "    \n",
    "    # Get approximate polygons\n",
    "    approx = cv2.approxPolyDP(cnt, 0.01*cv2.arcLength(cnt,True),True)\n",
    "    \n",
    "    if len(approx) == 3:\n",
    "        shape_name = \"Triangle\"\n",
    "        cv2.drawContours(image,[cnt],0,(0,255,0),-1)\n",
    "        \n",
    "        # Find contour center to place text at the center\n",
    "        M = cv2.moments(cnt)\n",
    "        cx = int(M['m10'] / M['m00'])\n",
    "        cy = int(M['m01'] / M['m00'])\n",
    "        cv2.putText(image, shape_name, (cx-50, cy), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 0), 1)\n",
    "    \n",
    "    elif len(approx) == 4:\n",
    "        x,y,w,h = cv2.boundingRect(cnt)\n",
    "        M = cv2.moments(cnt)\n",
    "        cx = int(M['m10'] / M['m00'])\n",
    "        cy = int(M['m01'] / M['m00'])\n",
    "        \n",
    "        # Check to see if 4-side polygon is square or rectangle\n",
    "        # cv2.boundingRect returns the top left and then width and \n",
    "        if abs(w-h) <= 3:\n",
    "            shape_name = \"Square\"\n",
    "            \n",
    "            # Find contour center to place text at the center\n",
    "            cv2.drawContours(image, [cnt], 0, (0, 125 ,255), -1)\n",
    "            cv2.putText(image, shape_name, (cx-50, cy), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 0), 1)\n",
    "        else:\n",
    "            shape_name = \"Rectangle\"\n",
    "            \n",
    "            # Find contour center to place text at the center\n",
    "            cv2.drawContours(image, [cnt], 0, (0, 0, 255), -1)\n",
    "            M = cv2.moments(cnt)\n",
    "            cx = int(M['m10'] / M['m00'])\n",
    "            cy = int(M['m01'] / M['m00'])\n",
    "            cv2.putText(image, shape_name, (cx-50, cy), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 0), 1)\n",
    "            \n",
    "    elif len(approx) == 10:\n",
    "        shape_name = \"Star\"\n",
    "        cv2.drawContours(image, [cnt], 0, (255, 255, 0), -1)\n",
    "        M = cv2.moments(cnt)\n",
    "        cx = int(M['m10'] / M['m00'])\n",
    "        cy = int(M['m01'] / M['m00'])\n",
    "        cv2.putText(image, shape_name, (cx-50, cy), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 0), 1)\n",
    "        \n",
    "        \n",
    "        \n",
    "    elif len(approx) >= 15:\n",
    "        shape_name = \"Circle\"\n",
    "        cv2.drawContours(image, [cnt], 0, (0, 255, 255), -1)\n",
    "        M = cv2.moments(cnt)\n",
    "        cx = int(M['m10'] / M['m00'])\n",
    "        cy = int(M['m01'] / M['m00'])\n",
    "        cv2.putText(image, shape_name, (cx-50, cy), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 0), 1)\n",
    "\n",
    "    cv2.imshow('Identifying Shapes',image)\n",
    "    cv2.waitKey(0)\n",
    "    \n",
    "cv2.destroyAllWindows()"
   ]
  }
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