Display Cv Mat Image

The first argument is the title of the window and the second argument is the cv mat object that will be shown.

Display cv mat image.

It is more efficient than manually converting the pixels to the qimage but you have to keep the original cv mat image in memory. I m trying to use opencv to calculate real rime optical flow and display it in ros. Then the image is shown using a call to the cv imshow function. Basic operations with images accessing pixel intensity values.

Mat image 600 800 cv 8uc3 scalar 100 250 30. In order to get pixel intensity value you have to know the type of an image and the number of channels. Explain how to load an image from a file and display the image in a window with opencv c examples. I ve used uvc camera and cv bridge to capture images with ros and convert them to cv mat.

Qimage img uchar mat data mat cols mat rows qimage format rgb32. The gui needed to display the frames of the video as it was playing so the user could see the video at the same time as it was being analysed. If the mat is 8 bit unsigned it is displayed as is. Because we want our window to be displayed until the user presses a key otherwise the program would end far too quickly we use the cv waitkey function whose only parameter is just how long should it wait for a.

If the mat is 16 bit unsigned or 32 bit integer the pixels are divided by 256. Then i m using calcopticalflowfarneback to calculate optical flow which returns a cv mat optical flow image of type cv 32fc2. Image data can be shared between sl mat and cv mat by having the both memory pointers pointing to the same address. However this meant converting the cv mat image to an image source to display in the image control.

Load display image load image from file and display. We use cv imshow canvassource mat to display it. Use cv imdecode and cv imencode to read and write an image from to memory rather than a file. The function may scale the mat depending on its depth.

That is the value range 0 255 256 is mapped to 0 255. Note format of the file is determined by its extension. Mat with channels stored in rgba order. Threrefore no data transfer is required between the two matrices.

The zed sdk provides its own sl mat class to store image data with a structure and data types similar to opencv cv mat. The task using provided opencv s functionality seems fairly easy. Opencv tutorial c home. To do this i had an image control on my wpf gui which would be used to display the frames.