Load a jpg image from memory [closed]

asked 2016-06-20 04:50:19 -0600

peak@opencv gravatar image

From an IP camera I've read in a jpg image to a buffer in memory. If I write this buffer to a file "picture.jpg", I can open it directly in Windows. I can also open the file with OpenCV: Mat image; image = imread("picture.jpg"); imshow("video", image);

Is there a way to directly pass the memory buffer to OpenCV? Casting it to InputArray ends in error.

Best regards, Peak

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Closed for the following reason the question is answered, right answer was accepted by berak
close date 2016-06-20 06:59:37.300353

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imdecode()

berak gravatar imageberak ( 2016-06-20 05:00:22 -0600 )edit

Well, as I said, casting the (byte) buffer to InputArray throws an error: OpenCV Error: Assertion failed (0 <= i && i < (int)v.size()) in cv::_InputArray

peak@opencv gravatar imagepeak@opencv ( 2016-06-20 05:16:25 -0600 )edit

ok, please show your code.

berak gravatar imageberak ( 2016-06-20 05:36:00 -0600 )edit

Cannot paste code. Formats ugly regardless of code window or not

peak@opencv gravatar imagepeak@opencv ( 2016-06-20 05:41:20 -0600 )edit

try to read it into vector<uchar> not a BYTE *

berak gravatar imageberak ( 2016-06-20 05:44:17 -0600 )edit
  • add the code to your question
  • use the 10101 button to format it
berak gravatar imageberak ( 2016-06-20 05:51:32 -0600 )edit

I did that

peak@opencv gravatar imagepeak@opencv ( 2016-06-20 05:53:44 -0600 )edit


    BYTE *g_image; // byte array for the jpg picture from the camera
    // <allocate g_image, read from camera to g_image>
    // g_image now contains a jpg image of approx 40 000 bytes and displays ok if saved to file
    //
    Mat image;
    image = imdecode((InputArray)g_image, CV_LOAD_IMAGE_UNCHANGED); // Error here, unhandled exeption from OpenCV
    imshow("video", image);


peak@opencv gravatar imagepeak@opencv ( 2016-06-20 05:54:22 -0600 )edit

again, use a vector, not a pointer

berak gravatar imageberak ( 2016-06-20 05:59:32 -0600 )edit

I did that (you see the old code) and it's working now. Thank You!

peak@opencv gravatar imagepeak@opencv ( 2016-06-20 06:53:44 -0600 )edit
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