Crop-Rect does not have an effect

[CobraCalle]

Hello,

I would like to crop the image from the camera to a specific rect, but this does not have any effect...

Here is my code: MMALCamera cam = MMALCamera.Instance;

        MMALCameraConfig.Resolution = Resolution.As2MPixel;
        MMALCameraConfig.EncodingSubFormat = MMALEncoding.BGR24;
        MMALCameraConfig.VideoStabilisation = false;

        var cropRect = new System.Drawing.Rectangle(177, 64, 1174, 1136);

        using (var imgCaptureHandler = new OpenCvMatCaptureHandler(MMALCameraConfig.Resolution))
        using (var splitter = new MMALSplitterComponent())
        using (var nullSink = new MMALNullSinkComponent())
        {
            cam.ConfigureCameraSettings();

            var splitterInputConfig = new MMALPortConfig(MMALEncoding.OPAQUE, MMALEncoding.BGR24, crop: cropRect);
            var splitterOutputConfig = new MMALPortConfig(MMALEncoding.BGR24, MMALEncoding.BGR24);

            // Create our component pipeline.        
            splitter
                .ConfigureInputPort(splitterInputConfig, cam.Camera.VideoPort, null)
                .ConfigureOutputPort<FastStillPort>(0, splitterOutputConfig, imgCaptureHandler);

            cam.Camera.VideoPort.ConnectTo(splitter);
            cam.Camera.PreviewPort.ConnectTo(nullSink);

            // Camera warm up time
            await Task.Delay(2000);

            CancellationTokenSource cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));

            await cam.ProcessAsync(cam.Camera.VideoPort, cts.Token);
        }

[techyian]

I believe you will want to set the ROI against the camera itself and you should be using MMALCameraConfig.ROI which accepts a Zoom struct. Valid range is between 0 - 1.0.

[CobraCalle]

yes, I treid that... but if I apply the values from the wiki (0.5, 0.5, 0.1, 0.1) the resulting frames are still 1600x1200 (in my case)... as I understand those values the result should be 10% of the height and width from the center... or is it allways a zoom and it is not possible to crop an area to reduce the frame size (and speed up the fps)?

[techyian]

It isn't a physical "crop" as you would usually expect, but instead it will focus on an area of the image keeping the original resolution. That's how the native MMAL library works so I don't have any control over that unfortunately.

[CobraCalle]

OK... checked.. thanks a lot 👍