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Posts Tagged ‘input images’

Assessing the pixel values of an image

Posted by Hemprasad Y. Badgujar on March 14, 2015



Assessing the pixel values of an image

#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "iostream"
 
using namespace cv;
using namespace std;
 
int main( )
{
 
 Mat src1;
 src1 = imread("lena.jpg", CV_LOAD_IMAGE_COLOR); 
 namedWindow( "Original image", CV_WINDOW_AUTOSIZE ); 
 imshow( "Original image", src1 ); 
 
 Mat gray;
 cvtColor(src1, gray, CV_BGR2GRAY);
 namedWindow( "Gray image", CV_WINDOW_AUTOSIZE ); 
 imshow( "Gray image", gray );
 
 // know the number of channels the image has
 cout<<"original image channels: "<<src1.channels()<<"gray image="" channels:="" "<="" *******************="" read="" the="" pixel="" intensity="" *********************="" single="" channel="" grey="" scale="" (type="" 8uc1)="" and="" coordinates="" x="5" y="2" by="" convention,="" {row="" number="y}" {column="" intensity.val[0]="" contains="" a="" value="" from="" 0="" to="" 255="" scalar="" intensity1="gray.at(2," 5);="" cout="" <<="" "intensity=" << endl << " "="" intensity1.val[0]="" endl="" endl;="" 3="" with="" bgr="" color="" 8uc3)="" values="" can="" be="" stored="" in="" "int"="" or="" "uchar".="" here="" int="" is="" used.="" vec3b="" intensity2="src1.at(10,15);" blue="intensity2.val[0];" green="intensity2.val[1];" red="intensity2.val[2];" write="" **********************="" this="" an="" example="" opencv="" 2.4.6.0="" documentation="" mat="" h(10,="" 10,="" cv_64f);="" for(int="" i="0;" <="" h.rows;="" i++)="" j="0;" h.cols;="" j++)="" h.at(i,j)="1./(i+j+1);" cout<<h<<endl<<endl;="" modify="" pixels="" of="" for="" (int="" {="" j<src1.cols;="" src1.at<vec3b="">(i,j)[0] = 0;
 src1.at(i,j)[1] = 200;
 src1.at(i,j)[2] = 0; 
 }
 }
 namedWindow( "Modify pixel", CV_WINDOW_AUTOSIZE ); 
 imshow( "Modify pixel", src1 );
 
 waitKey(0); 
 return 0;
}
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Posted in OpenCV, OpenCV Tutorial | Tagged: , , , , | Leave a Comment »

Display more than one image in a single window

Posted by Hemprasad Y. Badgujar on February 6, 2015


There is no inbuilt support to display more than one image in OpenCV. Here is a function illustrating how to display more than one image in a single window using Intel OpenCV. The method used is to set the ROIs of a Single Big image and then resizing and copying the input images on to the Single Big Image.

  1#include <cv.h>
  2#include <highgui.h>
  3
  4#include <stdio.h>
  5#include <stdarg.h>
  6
  7/*Function///////////////////////////////////////////////////////////////
  8
  9Name:       cvShowManyImages
 10
 11Purpose:    This is a function illustrating how to display more than one 
 12               image in a single window using Intel OpenCV
 13
 14Parameters: char *title: Title of the window to be displayed
 15            int nArgs:   Number of images to be displayed
 16            ...:         IplImage*, which contains the images
 17
 18Language:   C++
 19
 20The method used is to set the ROIs of a Single Big image and then resizing 
 21and copying the input images on to the Single Big Image.
 22
 23This function does not stretch the image... 
 24It resizes the image without modifying the width/height ratio..
 25
 26This function can be called like this:
 27
 28cvShowManyImages("Images", 2, img1, img2);
 29or
 30cvShowManyImages("Images", 5, img2, img2, img3, img4, img5);
 31
 32This function can display upto 12 images in a single window.
 33It does not check whether the arguments are of type IplImage* or not.
 34The maximum window size is 700 by 660 pixels.
 35Does not display anything if the number of arguments is less than
 36    one or greater than 12.
 37
 38If you pass a pointer that is not IplImage*, Error will occur.
 39Take care of the number of arguments you pass, and the type of arguments, 
 40which should be of type IplImage* ONLY.
 41
 42Idea was from [[BettySanchi]] of OpenCV Yahoo! Groups.
 43
 44If you have trouble compiling and/or executing
 45this code, I would like to hear about it.
 46
 47You could try posting on the OpenCV Yahoo! Groups
 48[url]http://groups.yahoo.com/group/OpenCV/messages/ [/url]
 49
 50Parameswaran, 
 51Chennai, India.
 52
 53cegparamesh[at]gmail[dot]com            
 54
 55...
 56///////////////////////////////////////////////////////////////////////*/
 57
 58void cvShowManyImages(char* title, int nArgs, ...) {
 59
 60    // img - Used for getting the arguments 
 61    IplImage *img;
 62
 63    // [[DispImage]] - the image in which input images are to be copied
 64    IplImage *DispImage;
 65
 66    int size;
 67    int i;
 68    int m, n;
 69    int x, y;
 70
 71    // w - Maximum number of images in a row 
 72    // h - Maximum number of images in a column 
 73    int w, h;
 74
 75    // scale - How much we have to resize the image
 76    float scale;
 77    int max;
 78
 79    // If the number of arguments is lesser than 0 or greater than 12
 80    // return without displaying 
 81    if(nArgs <= 0) {
 82        printf("Number of arguments too small....\n");
 83        return;
 84    }
 85    else if(nArgs > 12) {
 86        printf("Number of arguments too large....\n");
 87        return;
 88    }
 89    // Determine the size of the image, 
 90    // and the number of rows/cols 
 91    // from number of arguments 
 92    else if (nArgs == 1) {
 93        w = h = 1;
 94        size = 300;
 95    }
 96    else if (nArgs == 2) {
 97        w = 2; h = 1;
 98        size = 300;
 99    }
100    else if (nArgs == 3 || nArgs == 4) {
101        w = 2; h = 2;
102        size = 300;
103    }
104    else if (nArgs == 5 || nArgs == 6) {
105        w = 3; h = 2;
106        size = 200;
107    }
108    else if (nArgs == 7 || nArgs == 8) {
109        w = 4; h = 2;
110        size = 200;
111    }
112    else {
113        w = 4; h = 3;
114        size = 150;
115    }
116
117    // Create a new 3 channel image
118    [[DispImage]] = cvCreateImage( cvSize(100 + size*w, 60 + size*h), 8, 3 );
119
120    // Used to get the arguments passed
121    va_list args;
122    va_start(args, nArgs);
123
124    // Loop for nArgs number of arguments
125    for (i = 0, m = 20, n = 20; i < nArgs; i++, m += (20 + size)) {
126
127        // Get the Pointer to the IplImage
128        img = va_arg(args, IplImage*);
129
130        // Check whether it is NULL or not
131        // If it is NULL, release the image, and return
132        if(img == 0) {
133            printf("Invalid arguments");
134            cvReleaseImage(&DispImage);
135            return;
136        }
137
138        // Find the width and height of the image
139        x = img->width;
140        y = img->height;
141
142        // Find whether height or width is greater in order to resize the image
143        max = (x > y)? x: y;
144
145        // Find the scaling factor to resize the image
146        scale = (float) ( (float) max / size );
147
148        // Used to Align the images
149        if( i % w == 0 && m!= 20) {
150            m = 20;
151            n+= 20 + size;
152        }
153
154        // Set the image ROI to display the current image
155        cvSetImageROI(DispImage, cvRect(m, n, (int)( x/scale ), (int)( y/scale )));
156
157        // Resize the input image and copy the it to the Single Big Image
158        cvResize(img, DispImage);
159
160        // Reset the ROI in order to display the next image
161        cvResetImageROI(DispImage);
162    }
163
164    // Create a new window, and show the Single Big Image
165    cvNamedWindow( title, 1 );
166    cvShowImage( title, DispImage);
167
168    cvWaitKey();
169    cvDestroyWindow(title);
170
171    // End the number of arguments
172    va_end(args);
173
174    // Release the Image Memory
175    cvReleaseImage(&DispImage);
176}
177

You can use this function as in this sample program:

 1int main() {
 2
 3    IplImage *img1 = cvLoadImage("Image01.jpg");
 4
 5    IplImage *img2 = cvLoadImage("Image02.jpg");
 6
 7    IplImage *img3 = cvLoadImage("Image03.jpg");
 8
 9    IplImage *img4 = cvLoadImage("Image04.jpg");
10
11    IplImage *img5 = cvLoadImage("Image05.jpg");
12
13    IplImage *img6 = cvLoadImage("Image06.jpg");
14
15    cvShowManyImages("Image", 6, img1, img2, img3, img4, img5, img6);
16
17    return 0;
18
19}
20

The method used is to set the ROIs of a Single Big image and then resizing and copying the input images on to the Single Big Image.

This function does not stretch the image… It resizes the image without modifying the width/height ratio..

This function can be called like this:

1   cvShowManyImages("Image", 2, img1, img2);

or

1   cvShowManyImages("Image", 6, img1, img2, img3, img4, img5, img6);

upto 12 images.

This function can display upto 12 images in a single window. It does not check whether the arguments are of type IplImage* or not. The maximum window size is 700 by 660 pixels. Does not display anything if the number of arguments is less than one or greater than 12.

If you pass a pointer that is not IplImage*, Error will occur. Take care of the number of arguments you pass, and the type of arguments, which should be of type IplImage* ONLY.

Idea was from BettySanchi of OpenCV Yahoo! Groups.

If you have trouble compiling and/or executing this code, I would like to hear about it.

Here is a sample ScreenShot:

Posted in Computer Vision, GPU (CUDA), Image / Video Filters, OpenCV, PARALLEL | Tagged: , | Leave a Comment »

 
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