Merge pull request #15991 from collinbrake:feature_grammar_fixes_8

doc/py_tutorials/py_imgproc/py_colorspaces/py_colorspaces.markdown

@@ -5,44 +5,44 @@ Goal
 ----
 
 -   In this tutorial, you will learn how to convert images from one color-space to another, like
-    BGR \f$\leftrightarrow\f$ Gray, BGR \f$\leftrightarrow\f$ HSV etc.
--   In addition to that, we will create an application which extracts a colored object in a video
--   You will learn following functions : **cv.cvtColor()**, **cv.inRange()** etc.
+    BGR \f$\leftrightarrow\f$ Gray, BGR \f$\leftrightarrow\f$ HSV, etc.
+-   In addition to that, we will create an application to extract a colored object in a video
+-   You will learn the following functions: **cv.cvtColor()**, **cv.inRange()**, etc.
 
 Changing Color-space
 --------------------
 
 There are more than 150 color-space conversion methods available in OpenCV. But we will look into
-only two which are most widely used ones, BGR \f$\leftrightarrow\f$ Gray and BGR \f$\leftrightarrow\f$ HSV.
+only two, which are most widely used ones: BGR \f$\leftrightarrow\f$ Gray and BGR \f$\leftrightarrow\f$ HSV.
 
 For color conversion, we use the function cv.cvtColor(input_image, flag) where flag determines the
 type of conversion.
 
-For BGR \f$\rightarrow\f$ Gray conversion we use the flags cv.COLOR_BGR2GRAY. Similarly for BGR
+For BGR \f$\rightarrow\f$ Gray conversion, we use the flag cv.COLOR_BGR2GRAY. Similarly for BGR
 \f$\rightarrow\f$ HSV, we use the flag cv.COLOR_BGR2HSV. To get other flags, just run following
-commands in your Python terminal :
+commands in your Python terminal:
 @code{.py}
 >>> import cv2 as cv
 >>> flags = [i for i in dir(cv) if i.startswith('COLOR_')]
 >>> print( flags )
 @endcode
-@note For HSV, Hue range is [0,179], Saturation range is [0,255] and Value range is [0,255].
+@note For HSV, hue range is [0,179], saturation range is [0,255], and value range is [0,255].
 Different software use different scales. So if you are comparing OpenCV values with them, you need
 to normalize these ranges.
 
 Object Tracking
 ---------------
 
-Now we know how to convert BGR image to HSV, we can use this to extract a colored object. In HSV, it
-is more easier to represent a color than in BGR color-space. In our application, we will try to extract
+Now that we know how to convert a BGR image to HSV, we can use this to extract a colored object. In HSV, it
+is easier to represent a color than in BGR color-space. In our application, we will try to extract
 a blue colored object. So here is the method:
 
 -   Take each frame of the video
 -   Convert from BGR to HSV color-space
 -   We threshold the HSV image for a range of blue color
--   Now extract the blue object alone, we can do whatever on that image we want.
+-   Now extract the blue object alone, we can do whatever we want on that image.
 
-Below is the code which are commented in detail :
+Below is the code which is commented in detail:
 @code{.py}
 import cv2 as cv
 import numpy as np
@@ -80,18 +80,18 @@ Below image shows tracking of the blue object:
 
 ![image](images/frame.jpg)
 
-@note There are some noises in the image. We will see how to remove them in later chapters.
+@note There is some noise in the image. We will see how to remove it in later chapters.
 
 @note This is the simplest method in object tracking. Once you learn functions of contours, you can
-do plenty of things like find centroid of this object and use it to track the object, draw diagrams
-just by moving your hand in front of camera and many other funny stuffs.
+do plenty of things like find the centroid of an object and use it to track the object, draw diagrams
+just by moving your hand in front of a camera, and other fun stuff.
 
 How to find HSV values to track?
 --------------------------------
 
 This is a common question found in [stackoverflow.com](http://www.stackoverflow.com). It is very simple and
 you can use the same function, cv.cvtColor(). Instead of passing an image, you just pass the BGR
-values you want. For example, to find the HSV value of Green, try following commands in Python
+values you want. For example, to find the HSV value of Green, try the following commands in a Python
 terminal:
 @code{.py}
 >>> green = np.uint8([[[0,255,0 ]]])
@@ -99,7 +99,7 @@ terminal:
 >>> print( hsv_green )
 [[[ 60 255 255]]]
 @endcode
-Now you take [H-10, 100,100] and [H+10, 255, 255] as lower bound and upper bound respectively. Apart
+Now you take [H-10, 100,100] and [H+10, 255, 255] as the lower bound and upper bound respectively. Apart
 from this method, you can use any image editing tools like GIMP or any online converters to find
 these values, but don't forget to adjust the HSV ranges.
 
@@ -109,5 +109,5 @@ Additional Resources
 Exercises
 ---------
 
--#  Try to find a way to extract more than one colored objects, for eg, extract red, blue, green
-    objects simultaneously.
+-#  Try to find a way to extract more than one colored object, for example, extract red, blue, and green
+objects simultaneously.

doc/py_tutorials/py_imgproc/py_filtering/py_filtering.markdown

@@ -5,24 +5,24 @@ Goals
 -----
 
 Learn to:
-    -   Blur the images with various low pass filters
+    -   Blur images with various low pass filters
     -   Apply custom-made filters to images (2D convolution)
 
 2D Convolution ( Image Filtering )
 ----------------------------------
 
-As in one-dimensional signals, images also can be filtered with various low-pass filters(LPF),
-high-pass filters(HPF) etc. LPF helps in removing noises, blurring the images etc. HPF filters helps
-in finding edges in the images.
+As in one-dimensional signals, images also can be filtered with various low-pass filters (LPF),
+high-pass filters (HPF), etc. LPF helps in removing noise, blurring images, etc. HPF filters help
+in finding edges in images.
 
 OpenCV provides a function **cv.filter2D()** to convolve a kernel with an image. As an example, we
-will try an averaging filter on an image. A 5x5 averaging filter kernel will look like below:
+will try an averaging filter on an image. A 5x5 averaging filter kernel will look like the below:
 
 \f[K =  \frac{1}{25} \begin{bmatrix} 1 & 1 & 1 & 1 & 1  \\ 1 & 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 & 1 \end{bmatrix}\f]
 
-Operation is like this: keep this kernel above a pixel, add all the 25 pixels below this kernel,
-take its average and replace the central pixel with the new average value. It continues this
-operation for all the pixels in the image. Try this code and check the result:
+The operation works like this: keep this kernel above a pixel, add all the 25 pixels below this kernel,
+take the average, and replace the central pixel with the new average value. This operation is continued
+for all the pixels in the image. Try this code and check the result:
 @code{.py}
 import numpy as np
 import cv2 as cv
@@ -47,20 +47,20 @@ Image Blurring (Image Smoothing)
 --------------------------------
 
 Image blurring is achieved by convolving the image with a low-pass filter kernel. It is useful for
-removing noises. It actually removes high frequency content (eg: noise, edges) from the image. So
-edges are blurred a little bit in this operation. (Well, there are blurring techniques which doesn't
-blur the edges too). OpenCV provides mainly four types of blurring techniques.
+removing noise. It actually removes high frequency content (eg: noise, edges) from the image. So
+edges are blurred a little bit in this operation (there are also blurring techniques which don't
+blur the edges). OpenCV provides four main types of blurring techniques.
 
 ### 1. Averaging
 
-This is done by convolving image with a normalized box filter. It simply takes the average of all
-the pixels under kernel area and replace the central element. This is done by the function
+This is done by convolving an image with a normalized box filter. It simply takes the average of all
+the pixels under the kernel area and replaces the central element. This is done by the function
 **cv.blur()** or **cv.boxFilter()**. Check the docs for more details about the kernel. We should
-specify the width and height of kernel. A 3x3 normalized box filter would look like below:
+specify the width and height of the kernel. A 3x3 normalized box filter would look like the below:
 
 \f[K =  \frac{1}{9} \begin{bmatrix} 1 & 1 & 1  \\ 1 & 1 & 1 \\ 1 & 1 & 1 \end{bmatrix}\f]
 
-@note If you don't want to use normalized box filter, use **cv.boxFilter()**. Pass an argument
+@note If you don't want to use a normalized box filter, use **cv.boxFilter()**. Pass an argument
 normalize=False to the function.
 
 Check a sample demo below with a kernel of 5x5 size:
@@ -85,12 +85,12 @@ Result:
 
 ### 2. Gaussian Blurring
 
-In this, instead of box filter, gaussian kernel is used. It is done with the function,
-**cv.GaussianBlur()**. We should specify the width and height of kernel which should be positive
-and odd. We also should specify the standard deviation in X and Y direction, sigmaX and sigmaY
-respectively. If only sigmaX is specified, sigmaY is taken as same as sigmaX. If both are given as
-zeros, they are calculated from kernel size. Gaussian blurring is highly effective in removing
-gaussian noise from the image.
+In this method, instead of a box filter, a Gaussian kernel is used. It is done with the function,
+**cv.GaussianBlur()**. We should specify the width and height of the kernel which should be positive
+and odd. We also should specify the standard deviation in the X and Y directions, sigmaX and sigmaY
+respectively. If only sigmaX is specified, sigmaY is taken as the same as sigmaX. If both are given as
+zeros, they are calculated from the kernel size. Gaussian blurring is highly effective in removing
+Gaussian noise from an image.
 
 If you want, you can create a Gaussian kernel with the function, **cv.getGaussianKernel()**.
 
@@ -104,14 +104,14 @@ Result:
 
 ### 3. Median Blurring
 
-Here, the function **cv.medianBlur()** takes median of all the pixels under kernel area and central
+Here, the function **cv.medianBlur()** takes the median of all the pixels under the kernel area and the central
 element is replaced with this median value. This is highly effective against salt-and-pepper noise
-in the images. Interesting thing is that, in the above filters, central element is a newly
+in an image. Interestingly, in the above filters, the central element is a newly
 calculated value which may be a pixel value in the image or a new value. But in median blurring,
-central element is always replaced by some pixel value in the image. It reduces the noise
+the central element is always replaced by some pixel value in the image. It reduces the noise
 effectively. Its kernel size should be a positive odd integer.
 
-In this demo, I added a 50% noise to our original image and applied median blur. Check the result:
+In this demo, I added a 50% noise to our original image and applied median blurring. Check the result:
 @code{.py}
 median = cv.medianBlur(img,5)
 @endcode
@@ -122,19 +122,19 @@ Result:
 ### 4. Bilateral Filtering
 
 **cv.bilateralFilter()** is highly effective in noise removal while keeping edges sharp. But the
-operation is slower compared to other filters. We already saw that gaussian filter takes the a
-neighbourhood around the pixel and find its gaussian weighted average. This gaussian filter is a
+operation is slower compared to other filters. We already saw that a Gaussian filter takes the
+neighbourhood around the pixel and finds its Gaussian weighted average. This Gaussian filter is a
 function of space alone, that is, nearby pixels are considered while filtering. It doesn't consider
-whether pixels have almost same intensity. It doesn't consider whether pixel is an edge pixel or
+whether pixels have almost the same intensity. It doesn't consider whether a pixel is an edge pixel or
 not. So it blurs the edges also, which we don't want to do.
 
-Bilateral filter also takes a gaussian filter in space, but one more gaussian filter which is a
-function of pixel difference. Gaussian function of space make sure only nearby pixels are considered
-for blurring while gaussian function of intensity difference make sure only those pixels with
-similar intensity to central pixel is considered for blurring. So it preserves the edges since
+Bilateral filtering also takes a Gaussian filter in space, but one more Gaussian filter which is a
+function of pixel difference. The Gaussian function of space makes sure that only nearby pixels are considered
+for blurring, while the Gaussian function of intensity difference makes sure that only those pixels with
+similar intensities to the central pixel are considered for blurring. So it preserves the edges since
 pixels at edges will have large intensity variation.
 
-Below samples shows use bilateral filter (For details on arguments, visit docs).
+The below sample shows use of a bilateral filter (For details on arguments, visit docs).
 @code{.py}
 blur = cv.bilateralFilter(img,9,75,75)
 @endcode
@@ -142,7 +142,7 @@ Result:
 
 ![image](images/bilateral.jpg)
 
-See, the texture on the surface is gone, but edges are still preserved.
+See, the texture on the surface is gone, but the edges are still preserved.
 
 Additional Resources
 --------------------

doc/py_tutorials/py_imgproc/py_geometric_transformations/py_geometric_transformations.markdown

@@ -4,7 +4,7 @@ Geometric Transformations of Images {#tutorial_py_geometric_transformations}
 Goals
 -----
 
--   Learn to apply different geometric transformation to images like translation, rotation, affine
+-   Learn to apply different geometric transformations to images, like translation, rotation, affine
     transformation etc.
 -   You will see these functions: **cv.getPerspectiveTransform**
 
@@ -12,7 +12,7 @@ Transformations
 ---------------
 
 OpenCV provides two transformation functions, **cv.warpAffine** and **cv.warpPerspective**, with
-which you can have all kinds of transformations. **cv.warpAffine** takes a 2x3 transformation
+which you can perform all kinds of transformations. **cv.warpAffine** takes a 2x3 transformation
 matrix while **cv.warpPerspective** takes a 3x3 transformation matrix as input.
 
 ### Scaling
@@ -21,8 +21,8 @@ Scaling is just resizing of the image. OpenCV comes with a function **cv.resize(
 purpose. The size of the image can be specified manually, or you can specify the scaling factor.
 Different interpolation methods are used. Preferable interpolation methods are **cv.INTER_AREA**
 for shrinking and **cv.INTER_CUBIC** (slow) & **cv.INTER_LINEAR** for zooming. By default,
-interpolation method used is **cv.INTER_LINEAR** for all resizing purposes. You can resize an
-input image either of following methods:
+the interpolation method **cv.INTER_LINEAR** is used for all resizing purposes. You can resize an
+input image with either of following methods:
 @code{.py}
 import numpy as np
 import cv2 as cv
@@ -38,13 +38,13 @@ res = cv.resize(img,(2*width, 2*height), interpolation = cv.INTER_CUBIC)
 @endcode
 ### Translation
 
-Translation is the shifting of object's location. If you know the shift in (x,y) direction, let it
+Translation is the shifting of an object's location. If you know the shift in the (x,y) direction and let it
 be \f$(t_x,t_y)\f$, you can create the transformation matrix \f$\textbf{M}\f$ as follows:
 
 \f[M = \begin{bmatrix} 1 & 0 & t_x \\ 0 & 1 & t_y  \end{bmatrix}\f]
 
-You can take make it into a Numpy array of type np.float32 and pass it into **cv.warpAffine()**
-function. See below example for a shift of (100,50):
+You can take make it into a Numpy array of type np.float32 and pass it into the **cv.warpAffine()**
+function. See the below example for a shift of (100,50):
 @code{.py}
 import numpy as np
 import cv2 as cv
@@ -61,7 +61,7 @@ cv.destroyAllWindows()
 @endcode
 **warning**
 
-Third argument of the **cv.warpAffine()** function is the size of the output image, which should
+The third argument of the **cv.warpAffine()** function is the size of the output image, which should
 be in the form of **(width, height)**. Remember width = number of columns, and height = number of
 rows.
 
@@ -76,7 +76,7 @@ Rotation of an image for an angle \f$\theta\f$ is achieved by the transformation
 \f[M = \begin{bmatrix} cos\theta & -sin\theta \\ sin\theta & cos\theta   \end{bmatrix}\f]
 
 But OpenCV provides scaled rotation with adjustable center of rotation so that you can rotate at any
-location you prefer. Modified transformation matrix is given by
+location you prefer. The modified transformation matrix is given by
 
 \f[\begin{bmatrix} \alpha &  \beta & (1- \alpha )  \cdot center.x -  \beta \cdot center.y \\ - \beta &  \alpha &  \beta \cdot center.x + (1- \alpha )  \cdot center.y \end{bmatrix}\f]
 
@@ -84,7 +84,7 @@ where:
 
 \f[\begin{array}{l} \alpha =  scale \cdot \cos \theta , \\ \beta =  scale \cdot \sin \theta \end{array}\f]
 
-To find this transformation matrix, OpenCV provides a function, **cv.getRotationMatrix2D**. Check
+To find this transformation matrix, OpenCV provides a function, **cv.getRotationMatrix2D**. Check out the
 below example which rotates the image by 90 degree with respect to center without any scaling.
 @code{.py}
 img = cv.imread('messi5.jpg',0)
@@ -101,11 +101,11 @@ See the result:
 ### Affine Transformation
 
 In affine transformation, all parallel lines in the original image will still be parallel in the
-output image. To find the transformation matrix, we need three points from input image and their
-corresponding locations in output image. Then **cv.getAffineTransform** will create a 2x3 matrix
+output image. To find the transformation matrix, we need three points from the input image and their
+corresponding locations in the output image. Then **cv.getAffineTransform** will create a 2x3 matrix
 which is to be passed to **cv.warpAffine**.
 
-Check below example, and also look at the points I selected (which are marked in Green color):
+Check the below example, and also look at the points I selected (which are marked in green color):
 @code{.py}
 img = cv.imread('drawing.png')
 rows,cols,ch = img.shape
@@ -130,7 +130,7 @@ See the result:
 For perspective transformation, you need a 3x3 transformation matrix. Straight lines will remain
 straight even after the transformation. To find this transformation matrix, you need 4 points on the
 input image and corresponding points on the output image. Among these 4 points, 3 of them should not
-be collinear. Then transformation matrix can be found by the function
+be collinear. Then the transformation matrix can be found by the function
 **cv.getPerspectiveTransform**. Then apply **cv.warpPerspective** with this 3x3 transformation
 matrix.
 

doc/py_tutorials/py_imgproc/py_thresholding/py_thresholding.markdown

@@ -4,13 +4,13 @@ Image Thresholding {#tutorial_py_thresholding}
 Goal
 ----
 
--   In this tutorial, you will learn Simple thresholding, Adaptive thresholding and Otsu's thresholding.
+-   In this tutorial, you will learn simple thresholding, adaptive thresholding and Otsu's thresholding.
 -   You will learn the functions **cv.threshold** and **cv.adaptiveThreshold**.
 
 Simple Thresholding
 -------------------
 
-Here, the matter is straight forward. For every pixel, the same threshold value is applied.
+Here, the matter is straight-forward. For every pixel, the same threshold value is applied.
 If the pixel value is smaller than the threshold, it is set to 0, otherwise it is set to a maximum value.
 The function **cv.threshold** is used to apply the thresholding.
 The first argument is the source image, which **should be a grayscale image**.
@@ -65,11 +65,11 @@ Adaptive Thresholding
 
 In the previous section, we used one global value as a threshold.
 But this might not be good in all cases, e.g. if an image has different lighting conditions in different areas.
-In that case, adaptive thresholding thresholding can help.
+In that case, adaptive thresholding can help.
 Here, the algorithm determines the threshold for a pixel based on a small region around it.
 So we get different thresholds for different regions of the same image which gives better results for images with varying illumination.
 
-Additionally to the parameters described above, the method cv.adaptiveThreshold three input parameters:
+In addition to the parameters described above, the method cv.adaptiveThreshold takes three input parameters:
 
 The **adaptiveMethod** decides how the threshold value is calculated:
     -   cv.ADAPTIVE_THRESH_MEAN_C: The threshold value is the mean of the neighbourhood area minus the constant **C**.
@@ -168,8 +168,8 @@ Result:
 
 ### How does Otsu's Binarization work?
 
-This section demonstrates a Python implementation of Otsu's binarization to show how it works
-actually. If you are not interested, you can skip this.
+This section demonstrates a Python implementation of Otsu's binarization to show how it actually
+works. If you are not interested, you can skip this.
 
 Since we are working with bimodal images, Otsu's algorithm tries to find a threshold value (t) which
 minimizes the **weighted within-class variance** given by the relation: