docs: Add short info and list of opencv face recognizers

Author: informramiz

OpenCV-Face-Recognition-Python.ipynb

@@ -7,6 +7,13 @@
     "# Face Recognition with OpenCV and Python"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Introduction"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -26,6 +33,40 @@
     "![visualization](output/tom-shahrukh.png)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## OpenCV Face Recognizers"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "OpenCV has three built in face recognizers and thanks to OpenCV's clean coding, you can use any of them by just changing a single line of code. Below are the names of those face recognizers and their OpenCV calls. \n",
+    "\n",
+    "1. EigenFaces Recognizer - `cv2.face.createEigenFaceRecognizer()`\n",
+    "2. FisherFaces Recognizer - `cv2.face.createFisherFaceRecognizer()`\n",
+    "3. Local Binary Patterns Histograms (LBPH) Face Recognizer - `cv2.face.createLBPHFaceRecognizer()`"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Eigen Faces Recognizer"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -52,13 +93,15 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Import Required Modules"
+    "### Import Required Modules"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
+    "Before starting the actual coding we need to import the required modules for coding. So let's import them first. \n",
+    "\n",
     "- **cv2:** is _OpenCV_ module for Python which we will use for face detection and face recognition.\n",
     "- **os:** We will use this Python module to read our training directories and file names.\n",
     "- **numpy:** We will use this module to convert Python lists to numpy arrays as OpenCV face recognizers accept numpy arrays."
@@ -85,6 +128,13 @@
     "%matplotlib inline "
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Training Data"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -380,7 +430,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "As OpenCV comes equipped with three face recognizers.\n",
+    "As we know, OpenCV comes equipped with three face recognizers.\n",
     "\n",
     "1. EigenFace Recognizer: This can be created with `cv2.face.createEigenFaceRecognizer()`\n",
     "2. FisherFace Recognizer: This can be created with `cv2.face.createFisherFaceRecognizer()`\n",