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--- opencv_tutorials_t1 [2016/06/06 14:22] – joaomatos
+++ opencv_tutorials_t1 [2017/05/13 16:55] (current) – [Using your Webcam Image] acater
@@ Line 1: / Line 1: @@
-Tutorial 1 -
+===== Tutorial 1 =====
+ On this tutorial you will learn how to open an image , and change from RGB colored to gray scale and HSV.At the end you will learn the same thing but using the live webcam stream.
+I recommend you to type the code on your own to get familiarized with the program language. If you have trouble , the original code is attached bellow ( Running on Visual Studio 2015 + OpenCV 3.1 ) * Check the installation guide to make sure that you linked all the OpenCV modules to your Visual Studio.
+{{::basic_operations.rar|Basic operations using image}}
+{{::basic_operations_using_webcam.rar|Basic operations using webcam}}
+----
+===== Basic Operations =====
+{{ ::basic_op.jpg?direct |}}
 <Code:c++ linenums:1>
@@ Line 80: / Line 95: @@
 **Line 1 to 11**:
- First we have to include the modules from OpenCV that will be used on the program. Each modules has its own functions and Variables type. (For example: the Mat variable type , the cvtColor function , the imshow function , etc... - each one is inside of one OpenCV module , that needs to be included in order to make the program compile).
+ First we have to include the modules from OpenCV that will be used on the program. Each modules has its own functions and Variables type. (For example: the Mat variable type , the cvtColor function , the imshow function , etc... - each one is inside of one OpenCV module , that needs to be included in order to make the program compile). The "usingnamespace" is convenient to declare always because it avoid us to type cv::OpenCVFunction  or std::StandardFunction always before using the function for the opencv scope or standard scope.
@@ Line 127: / Line 142: @@
 **Line 20 to 37**
- First we have to open the image using the "imread" function , that takes the path of your image on your computer as argument. We can use the "resize" function to set the width and height of the picture (avoid to open big files) . A very useful function from OpenCV is the cvtColor , which convert the image "color type". The type of the conversion is set on the third argument - on this case , the color from the original picture is RGB , and we want to convert to grayscale (CV_BGR2GRAY) and convert to HSV (CV_BGR2HSV).
+ First we have to open the image using the **"imread"** function , that takes the path of your image on your computer as argument. We can use the **"resize"** function to set the width and height of the picture (avoid to open big files) . A very useful function from OpenCV is the **"cvtColor"** , which convert the image "color type". The type of the conversion is set on the third argument - on this case , the color from the original picture is RGB , and we want to convert to gray scale (CV_BGR2GRAY) and convert to HSV (CV_BGR2HSV).
+----
+<Code:c++ linenums:38>
+//Function to create windows to display your image. The type of the window
+	//can be defined on the second argument
+	//Can be omitted ( just use imshow ) if you want to use the default window properties.
+	namedWindow("Color Image", CV_WINDOW_NORMAL);
+	namedWindow("GrayScale Image", CV_WINDOW_NORMAL);
+	namedWindow("HSV Image", CV_WINDOW_NORMAL);
+	//function to show the image on the specified window (first argument)
+	imshow("Color Image", colorimage);
+	imshow("GrayScale Image", grayimage);
+	imshow("HSV image", hsvimage);
+	//Press any key to end the program
+	waitKey(0);
+	return 0;
+}
+</Code>
+**Line 20 to 37**
+ To show the results we first open a window , using the function **"namedWindow"** , which the second argument defines the window properties ( if it can be sized , etc.. ) . Then we use the **"imshow"** function to display the Mat variable (second argument) on the specified window ( first argument ). The **"namedWindow"** function can be omitted if you want to use the default window properties (auto size).
+----
+===== Using your Webcam Image =====
+ To use the webcam live video instead of an saved image, you just need to insert a infinite do loop , and your video will be a collection of frames from your webcam. The new code will be.
+<Code:c++ linenums:1>
+//Blocks that we will need on this program
+#include "opencv2/highgui/highgui.hpp"
+#include "opencv2/core/core.hpp"
+#include "opencv2/imgproc/imgproc.hpp"
+// declaring the namespaces
+using namespace std;
+using namespace cv;
+int main(int argc, char *argv[])
+{
+	//Declaring variables to store the colored,gray scale and HSV images
+	Mat colorimage;
+	Mat grayimage;
+	Mat hsvimage;
+	//Open the default camera
+	VideoCapture capture(0);
+	//Check for Failure
+	if (!capture.isOpened())
+	{
+		printf("Failed to open the webcam");
+	}
+	//Set Capture device properties.
+	capture.set(CV_CAP_PROP_FRAME_WIDTH, 640);
+	capture.set(CV_CAP_PROP_FRAME_HEIGHT, 480);
+	char key=0;
+		//Loop will stop if "q" is pressed in the keyboard
+		while (key != 'q')
+		{
+			//Capture a frame of the webcam live video and store it on the image variable
+			capture >> colorimage;
+		//Convert Color function.
+		//cvtColor(source image , converted image , type of conversion )
+		//You can check a list of possible convertions on the opencv website
+		// The third argument will define the conversion.
+		// COLOR TO GRAY (CV_BGR2GRAY)
+		cvtColor(colorimage, grayimage, CV_BGR2GRAY);
+		//COLOR TO HSV  ( CV_BGR2HSV)
+		cvtColor(colorimage, hsvimage, CV_BGR2HSV);
+		//Function to create windows to display your image. The type of the window
+		//can be defined on the second argument
+		//Can be omitted ( just use imshow ) if you want to use the default window properties.
+		namedWindow("Color Image", CV_WINDOW_NORMAL);
+		namedWindow("GrayScale Image", CV_WINDOW_NORMAL);
+		namedWindow("HSV Image", CV_WINDOW_NORMAL);
+		//function to show the image on the specified window (first argument)
+		imshow("Color Image", colorimage);
+		imshow("GrayScale Image", grayimage);
+		imshow("HSV image", hsvimage);
+		//Press q to end the program
+		key = waitKey(25);
+	}
+	return 0;
+}
+</Code>
+** What is changed ? **
+<Code:c++ linenums:20>
+//Open the default camera
+	VideoCapture capture(0);
+	//Check for Failure
+	if (!capture.isOpened())
+	{
+		printf("Failed to open the webcam");
+	}
+	//Set Capture device properties.
+	capture.set(CV_CAP_PROP_FRAME_WIDTH, 640);
+	capture.set(CV_CAP_PROP_FRAME_HEIGHT, 480);
+</Code>
+ We changed the **"imread"** for the **"VideoCapture"** which will capture from your default video source (capture(0)) and the **"resize"** for the **"capture.set"** function.
+----
+<Code:c++ linenums:34>
+char key=0;
+		//Loop will stop if "q" is pressed in the keyboard
+		while (key != 'q')
+		{
+                        //Capture a frame of the webcam live video and store it on the image variable
+			capture >> colorimage;
+</Code>
+The loop will run until the "q" key on the keyboard is pressed (we need to declare the key variable first ). The video shown on the images will be a collection of frames took from your webcam ( using the assign **capture >> colorimage**) the color image will store the webcam frame . The rest of the code is the same thing as the last code , converting to gray scale and HSV.  At the end we just need to assign the **"waitKey"** command to the key variable and close the loop.
+\\
+The video below demonstrates the program as it is run in real time.
+\\
+{{youtube>PqW0GsMVRd0?medium}}