why the captured image from code is not bright as normal captured image?

asked 2015-06-23 01:05:37 -0600

Akki
76 ●2 ●3 ●8

updated 2016-01-02 11:19:21 -0600

sturkmen

6772 ●3 ●48 ●79 https://github.com/stu...

Hello,

I am facing one problem regarding the capturing image from the USB camera. when I captured image without using coding i.e. directly from the camera than its give me bright image. but when i took image from capture image code from opencv than same image from same camera looks very dark.

what should be the probably reasons for this?? and i am using normal capture camera code only from tutorial. please guide me. waiting for suggestions.

Thank you very much in advance.

answered 2015-07-13 22:02:52 -0600

sturkmen

6772 ●3 ●48 ●79 https://github.com/stu...

updated 2015-07-16 04:26:21 -0600

when capturing image from webcam, if you grab only the first frame you will never get a quality image. you must let the camera to be warmed up.

let us test this stuation with the code below

#include "opencv2/opencv.hpp"

using namespace cv;

int main(int argc, char** argv)
{
    VideoCapture cap;

    if(!cap.open(0))
        return 0;

    Mat frame[5];

    for(int i=0; i<5; )
    {

        cap >> frame[i];

        if( !frame[i].empty() )
        {
            imshow(format("Frame - %d",i), frame[i]);
            i++;
        }
    }

    waitKey();
    return 0;
}

difference between 1st and 5th frame is blurriness on my cam. i think on some cams the brightness difference can occur.

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Comments

Thank you for your answer. I am trying to use your suggestion, but I am getting error at line imshow(format("Frame - %d",i), frame[i]);

Like , assertion failed. unrecognized or unsupported array type. can you please guide me how can I Solve this error. Thank you very much once again for your comment.

Akki ( 2015-07-15 05:06:12 -0600 )edit

@Akki i have edited the source. could you try it.

sturkmen ( 2015-07-16 04:28:10 -0600 )edit

may be you have a webcam with autofocus so you have to wait some frame

LBerger ( 2015-07-16 04:58:15 -0600 )edit

@Akki did you try the code again?. did you solve your problem?

sturkmen ( 2015-07-21 08:35:15 -0600 )edit

Thank you very much Sturkmen, Moment its working fine. Thank you very much for your suggestion.

Akki ( 2015-07-21 09:19:46 -0600 )edit

did you tried the code? i want to know your result. any difference between first and second frame?

sturkmen ( 2015-07-21 09:23:20 -0600 )edit

I tried the code... but there is not big changes between two frames. But its give time to the camera to set the auto focus before capturing the image.

Akki ( 2015-07-22 02:17:53 -0600 )edit

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