Display Cv Mat Image

Explain how to load an image from a file and display the image in a window with opencv c examples.

Display cv mat image.

Mat image 600 800 cv 8uc3 scalar 100 250 30. The first argument is the title of the window and the second argument is the cv mat object that will be shown. To do this i had an image control on my wpf gui which would be used to display the frames. To convert from cv mat to qimage you could try to use the qimage uchar data int width int height format format constructor as follows mat is a cv mat.

Mat with channels stored in rgba order. Then i m using calcopticalflowfarneback to calculate optical flow which returns a cv mat optical flow image of type cv 32fc2. That is the value range 0 255 256 is mapped to 0 255. In order to get pixel intensity value you have to know the type of an image and the number of channels.

Use cv imdecode and cv imencode to read and write an image from to memory rather than a file. Threrefore no data transfer is required between the two matrices. 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. Qimage img uchar mat data mat cols mat rows qimage format rgb32.

It creates an image which. I ve used uvc camera and cv bridge to capture images with ros and convert them to cv mat. Basic operations with images accessing pixel intensity values. The function may scale the mat depending on its depth.

The zed sdk provides its own sl mat class to store image data with a structure and data types similar to opencv cv mat. If the mat is 16 bit unsigned or 32 bit integer the pixels are divided by 256. Note format of the file is determined by its extension. This is one of many constructors available in mat class.

The task using provided opencv s functionality seems fairly easy. 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. If the mat is 8 bit unsigned it is displayed as is.

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. It is more efficient than manually converting the pixels to the qimage but you have to keep the original cv mat image in memory.