Différences

Ci-dessous, les différences entre deux révisions de la page.

--- diy:projets:chromakey [2018/06/25 08:58] – [Sources du projet] sdurand
+++ diy:projets:chromakey [2018/07/02 09:35] (Version actuelle) – [Sources du projet] sdurand
@@ Ligne 313: / Ligne 313: @@
 === "Émetteur" ===
+<code C++>
+#include <iostream>
+#include <chrono>
+#include <opencv2/opencv.hpp>
+#include <omp.h>
+#define WIDTH 1280
+#define HEIGHT 720
+#define FRAME_SIZE WIDTH*HEIGHT*3
+#define NUMBER_OF_FRAMES 150
+#define ALL_GOOD 0
+#define INVALID_ARGUMENTS -1
+#define INVALID_IMAGE -2
+// For a bit of comfort
+using namespace cv;
+// Simple function to test if a channel of a pixel (B, G or R) is within the interval [value - offset; value + offset]
+inline bool inBounds(int value, int bound, int offset) {
+	return abs(value - bound) <= offset;
+}
+// Most important part of the code:
+// Replaces the pixels of the frame close enough (depending of the offset) to the color B, G, R
+inline void chromakey(Mat& frame, int B, int G, int R, int offset, const Mat& background) {
+	// Using openMP was definitely worth on a Raspberry Pi 3 model B
+	#pragma omp parallel for
+	// Iterating on the rows of our frame
+	for(int i = 0; i < frame.rows; i++) {
+		// Using a pointer to the rows is the fastest way to access a matrix
+		Vec3b *Fi = frame.ptr<Vec3b>(i);
+		const Vec3b *Bi = background.ptr<Vec3b>(i);
+		// Iterating on the elements of each row
+		for(int j = 0; j < frame.cols; j++) {
+			// If the pixel (i, j) of our frame is close enough to B, G and R, we replace it with the color of the background (i, j) pixel
+			if(inBounds(Fi[j][0], B, offset) && inBounds(Fi[j][1], G, offset) && inBounds(Fi[j][2], R, offset)) {
+				for(int k = 0; k < 3; k++) {
+					Fi[j][k] = Bi[j][k];
+				}
+			}
+		}
+	}
+}
+int main(int argc, char** argv) {
+	// Just a simple parameters check
+	if(argc !=  6) {
+		std::cerr << "Usage: ./chrk R G B offset /path/to/background_image" << std::endl;
+		return INVALID_ARGUMENTS;
+	}
+	// This Mat contains our background
+	Mat background;
+	background = imread(argv[5]);
+	// Testing that the images size is the same as defined
+	// We could also just reshape the image, it would be a bit less restrictive
+	if(!background.data || background.cols != WIDTH || background.rows != HEIGHT) {
+		std::cerr << "ERROR: Invalid background image" << std::endl;
+		return INVALID_IMAGE;
+	}
+	int B, G, R, offset;
+	// Getting the parameters from the command line
+	std::istringstream rr(argv[1]);
+	std::istringstream rg(argv[2]);
+	std::istringstream rb(argv[3]);
+	std::istringstream rt(argv[4]);
+	rb >> B;
+	rg >> G;
+	rr >> R;
+	rt >> offset;
+	// This Mat will contain the images
+	Mat frame;
+	// Initializing the capture, should be equivalent to:
+	// VideoCapture cam(0);
+	VideoCapture cam(0);
+	// Setting the width and height of the capture as defined
+	// If not set, default resolution is 640*480
+	cam.set(3, WIDTH);
+	cam.set(4, HEIGHT);
+	// Adding the OpenCV JPEG parameters to a vector, this is used to encode a Mat with non-default settings
+	std::vector<int> jpg_parameters;
+	jpg_parameters.push_back(CV_IMWRITE_JPEG_QUALITY);
+	jpg_parameters.push_back(75);
+	std::vector<uchar> buffer;
+	for(int frame_count = 0; frame_count < NUMBER_OF_FRAMES; frame_count++) {
+		const auto start = std::chrono::high_resolution_clock::now();
+		do {
+			cam >> frame;
+		} while(frame.empty());
+		chromakey(frame, B, G, R, offset, background);
+		// Encoding the frame
+		imencode(".jpg", frame, buffer, jpg_parameters);
+		const unsigned int size = buffer.size();
+		// Writing the encoded image to stdout
+		// unsigned int and uchar size are the same on ARM and 64 bits regular computer
+		fwrite(&size, sizeof(unsigned int), 1, stdout);
+		fwrite(buffer.data(), sizeof(uchar), size, stdout);
+		// We use stderr to print an FPS counter and not because we are already writing images on stdout
+		const std::chrono::duration<float> elapsed = std::chrono::high_resolution_clock::now() - start;
+		std::cerr << "\rFPS: " << 1/elapsed.count();
+	}
+	std::cerr << std::endl;
+	return ALL_GOOD;
+}
+</code>
 === "Récepteur" ===
+<code C++>
+#include <iostream>
+#include <chrono>
+#include <opencv2/opencv.hpp>
+// WIDTH, HEIGHT and NUMBER_OF_FRAMES should always be set to the same value as in the transmitter
+#define WIDTH 1280
+#define HEIGHT 720
+// Maximum size of the received frame
+// In theory, if jpeg doesn't compress the image at all, it could be larger than that because of the format overhead
+// I'm not sure it can ever happen, so, as this program should not be used for critical stuff (it really should not), I'm just gonna assume it won't happen
+#define FRAME_SIZE WIDTH*HEIGHT*3
+#define NUMBER_OF_FRAMES 150
+#define ALL_GOOD 0
+int main(int argc, char **argv) {
+	// Actual size of the received frame
+	unsigned int size;
+	uchar buffer[FRAME_SIZE];
+	cv::Mat frame;
+	for(int frame_count = 0; frame_count < NUMBER_OF_FRAMES; frame_count++) {
+		// Reading the encoded image from stdin
+		// unsigned int and uchar size are the same on ARM and 64 bits regular computer
+		fread(&size, sizeof(unsigned int), 1, stdin);
+		fread(buffer, sizeof(uchar), size, stdin);
+		std::vector<uchar> data(buffer, buffer+size);
+		// Decoding the received frame
+		frame = cv::imdecode(cv::Mat(data), cv::IMREAD_UNCHANGED);
+		// Displaying the received frame
+		cv::imshow("frame", frame);
+		// This wait is mandatory for the image to actually display
+		cv::waitKey(1);
+	}
+	return ALL_GOOD;
+}
+</code>
 ----
-//Auteur: Sylvain D//
+//Auteur: S. Durand//