Dayama Pradeep's profile - activity

Sorry guys, Actually i was not getting proper output so i was doubting my image conversion from uchar to float, the logic for conversion which i arrived after a pretty long discussion with @berak is right. the problem which i rectified is with the Logic i applied for image processing @boaz001 Image processing i m doing on image is to findout minumum of RGB in an image and make it a single channel image, after this Add a patch to image with patch size of 15x15, and find minimum value of current pixcel in that patch, then move the patch further. This is the image processing Stuff i m doing. Error which I encountered during image processing is, the output should be a Dark Gray Scale image, but what I was getting is a Full Blank image as that of Blank Computer monitor after shut down

@berak, the reason i want to convert image into float is coz the processing of image will be more precise. After that previous disscusion we had on the same topic, i use the logic for conversion what we discussed then, but i t seems to be failed at the time of image processing

@berak, Hello again.. we had this same discussion on conversion of char to float here is the discuddion but when i do some image processing operation on that converted image i get problems

Hello

I m trying to convert an image from uchar to float but i get an error as Assertion failed

here is my code snippet

#include <stdio.h>
#include "opencv2/opencv.hpp"

using namespace cv;
using namespace std;

 Mat img = imread(img_name);

 if (img .empty()) 
{ 
    cerr << "no image"; return -1; 
}

 height = img.rows;
 width = img.cols;
 size = img.rows*img.cols;

 float* cpu_image = (float *)malloc((size+1) * 3 * sizeof(float));
 if (!cpu_image)
 {
    std::cout << "ERROR: Failed to allocate memory" << std::endl;
    return -1;
  }

  //converting image from uchar to float* pixcel-wise
  for (int i = 0; i < height; i++){
    for(int j = 0; j < width; j++)
    {
        for(int k = 0; k < 3; k++){
            cpu_image[(i * width + j) * 3 + k] = img.at<Vec<float,3> >(i,j)[k];
        }
    }
}
cpu_image[size] = 0;
cpu_image[size+1] = 0;
cpu_image[size+2] = 0;

    //converting image back to uchar from float
    Mat dest(height, width, CV_32FC3, cpu_image);
    imwrite(out_name, dest);

   free(cpu_image);

   return 0;

  }

Any advice pls...

@berak i couldn't get you.. The code has successfully worked for me.. you add the answer it i feel like somethings needed to be changed i ll edit it..

@beark please also let me know if there is any material available to learn IMAGE PROCESSING and PROGRAMMING USING OPENCV

@beark I cant post the answer by myself fpr 24 hours,

so here is the final code

#include<iostream>
#include<opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main()
{
 //load the image
 Mat src = imread("foggyHouse.jpg");

//read height, width data
int height = src.rows;
int width = src.cols;

//check whether image loaded is empty or not.
if (src.empty()) 
{ 
    cerr << "no image"; return -1; 
}

//convert image from CV::MAT to float*.
Mat dst;
src.convertTo(dst, CV_32F);
float *data = dst.ptr<float>();

//convert back the image from float* to CV::MAT.
Mat dest(height, width, CV_32FC3, data);

//print the image
imwrite("IMg.jpg", dest);

return 0;
}

@beark Thanks a lot... finally i m getting the output as i need.. i ll reply to my question.. i.e. i ll add the answer myself.. please check it..

sorry I didn't said you prior, In the above code I'm using imshow for source file, which results in displaying the image and hence the image is getting loaded properly

Edited the question.. Please check it @berak

I tried converting as you said i.e. using CV_8U but i get a error saying

First-chance exception at 0x528E0A14 (opencv_world300.dll) in Project3.exe: 0xC0000005: Access violation reading location 0x00137000. Unhandled exception at 0x528E0A14 (opencv_world300.dll) in Project3.exe: 0xC0000005: Access violation reading location 0x00137000.

code snippet is here

Mat dest;
dst.convertTo(dest,CV_8U);

i have also tried with other formats like CV_8UC1, CV_8UC3 etc.. but all gives same error

That's great..!! Its working..

But how do i convert back to cv::mat(string), such that i can print an image using imwrite

my plan was to convert an image from cv::mat to float*, do some image processing, again convert back to cv::mat and print it

for converting it to cv:mat i m using this

Mat dest(height, width, CV_32FC1, data);

is this fine?? i mean, am i heading in correct direction??

Hello I'm using VS2013 and openvc 3.0

Here I'm trying to read an image, convert it to float* from CV::MAT, do some processing, and again convert it back to CV::MAT from float* Here is the code snippet

  `
   #include<iostream>
    #include<opencv2/opencv.hpp>

   using namespace std;
   using namespace cv;

   int main()
  { 
        //read the image
        Mat src = imread("foggyHouse.jpg");

       //convert to float*
        Mat dst;
    src.convertTo(dst, CV_32F);
        float *data = dst.ptr<float>();

       //convert back to CV::MAT from float*
       Mat dest;
   dst.convertTo(dest,CV_8U);

      //print image
       imwrite("IMg.jpg", dest);

    return 0;
 }

` the problem is I'm getting an error saying

First-chance exception at 0x528E0A14 (opencv_world300.dll) in Project3.exe: 0xC0000005: Access violation reading location 0x00137000. Unhandled exception at 0x528E0A14 (opencv_world300.dll) in Project3.exe: 0xC0000005: Access violation reading location 0x00137000.

i tried other method to convert from CV:MAT to float* here is the code

int height = src.rows;
int width = src.cols;

   //convert from CV::MAT to float*
Mat dst;
src.convertTo(dst, CV_32F);
float *data = dst.ptr<float>();

    //convert from float*  to CV::MAT
    Mat dest(height, width, CV_32FC1, data);
imwrite("IMg.jpg", dest);

this is also giving the same error

Any suggestion or help will be appreciated.

Thanks