Added cropping of the input picture

Author: poljvd

test/v4l2_to_png/V4L2Grabber.cpp

@@ -37,13 +37,15 @@ static void yuv2rgb(uint8_t y, uint8_t u, uint8_t v, uint8_t & r, uint8_t & g, u
 }
 
 
-V4L2Grabber::V4L2Grabber(const std::string &device, int input, VideoStandard videoStandard, int frameDecimation, int pixelDecimation) :
+V4L2Grabber::V4L2Grabber(const std::string &device, int input, VideoStandard videoStandard, int cropHorizontal, int cropVertical, int frameDecimation, int pixelDecimation) :
 	_deviceName(device),
 	_ioMethod(IO_METHOD_MMAP),
 	_fileDescriptor(-1),
 	_buffers(),
 	_width(0),
 	_height(0),
+	_cropWidth(cropHorizontal),
+	_cropHeight(cropVertical),
 	_frameDecimation(std::max(1, frameDecimation)),
 	_pixelDecimation(std::max(1, pixelDecimation)),
 	_currentFrame(0)
@@ -590,14 +592,14 @@ void V4L2Grabber::process_image(const uint8_t * data)
 {
 	std::cout << "process image" << std::endl;
 
-	int width = (_width + _pixelDecimation/2) / _pixelDecimation;
-	int height = (_height + _pixelDecimation/2) / _pixelDecimation;
+	int width = (_width - 2 * _cropWidth + _pixelDecimation/2) / _pixelDecimation;
+	int height = (_height - 2 * _cropHeight + _pixelDecimation/2) / _pixelDecimation;
 
 	Image<ColorRgb> image(width, height);
 
-	for (int ySource = _pixelDecimation/2, yDest = 0; ySource < _height; ySource += _pixelDecimation, ++yDest)
+	for (int ySource = _cropHeight + _pixelDecimation/2, yDest = 0; ySource < _height - _cropHeight; ySource += _pixelDecimation, ++yDest)
 	{
-		for (int xSource = _pixelDecimation/2, xDest = 0; xSource < _width; xSource += _pixelDecimation, ++xDest)
+		for (int xSource = _cropWidth + _pixelDecimation/2, xDest = 0; xSource < _width - _cropWidth; xSource += _pixelDecimation, ++xDest)
 		{
 			int index = (_width * ySource + xSource) * 2;
 			uint8_t y = data[index+1];

test/v4l2_to_png/V4L2Grabber.h

@@ -19,7 +19,7 @@ class V4L2Grabber
 	};
 
 public:
-	V4L2Grabber(const std::string & device, int input, VideoStandard videoStandard, int frameDecimation, int pixelDecimation);
+	V4L2Grabber(const std::string & device, int input, VideoStandard videoStandard, int cropHorizontal, int cropVertical, int frameDecimation, int pixelDecimation);
 	virtual ~V4L2Grabber();
 
 	void start();
@@ -77,6 +77,8 @@ class V4L2Grabber
 
 	int _width;
 	int _height;
+	const int _cropWidth;
+	const int _cropHeight;
 	const int _frameDecimation;
 	const int _pixelDecimation;
 

test/v4l2_to_png/v4l2_to_png.cpp

@@ -57,13 +57,17 @@ int main(int argc, char** argv)
 		StringParameter &   argDevice             = parameters.add<StringParameter>       ('d', "device",         "The device to use [default=/dev/video0]");
 		VideoStandardParameter & argVideoStandard = parameters.add<VideoStandardParameter>('v', "video-standard", "The used video standard. Valid values are PAL. NYSC, or NO-CHANGE [default=PAL]");
 		IntParameter &      argInput              = parameters.add<IntParameter>          ('i', "input",          "Input channel [default=0]");
+		IntParameter &      argCropWidth          = parameters.add<IntParameter>          (0x0, "crop-width",     "Number of pixels to crop from the left and right sides in the picture before decimation [default=0]");
+		IntParameter &      argCropHeight         = parameters.add<IntParameter>          (0x0, "crop-height",    "Number of pixels to crop from the top and the bottom in the picture before decimation [default=0]");
 		IntParameter &      argSizeDecimation     = parameters.add<IntParameter>          ('s', "size-decimator", "Decimation factor for the output size [default=1]");
 		SwitchParameter<> & argHelp               = parameters.add<SwitchParameter<> >    ('h', "help",           "Show this help message and exit");
 
 		// set defaults
 		argDevice.setDefault("/dev/video0");
 		argVideoStandard.setDefault(V4L2Grabber::PAL);
 		argInput.setDefault(0);
+		argCropWidth.setDefault(0);
+		argCropHeight.setDefault(0);
 		argSizeDecimation.setDefault(1);
 
 		// parse all options
@@ -80,6 +84,8 @@ int main(int argc, char** argv)
 					argDevice.getValue(),
 					argInput.getValue(),
 					argVideoStandard.getValue(),
+					std::max(0, argCropWidth.getValue()),
+					std::max(0, argCropHeight.getValue()),
 					1,
 					argSizeDecimation.getValue());