In this tutorial you will learn how to use the 'mcc' module to detect colorcharts in a image. Here we will only use the basic detection algorithm. In the next tutorial you will see how you can improve detection accuracy using a neural network.
Building
When building OpenCV, run the following command to build all the contrib module:
cmake -D OPENCV_EXTRA_MODULES_PATH=<opencv_contrib>/modules/
Or only build the mcc module:
cmake -D OPENCV_EXTRA_MODULES_PATH=<opencv_contrib>/modules/mcc
Or make sure you check the mcc module in the GUI version of CMake: cmake-gui.
Source Code of the sample
run
<path_of_your_opencv_build_directory>/bin/example_mcc_chart_detection -t=<type_of_chart> -v=<optional_path_to_video_if_not_provided_webcam_will_be_used.mp4> --ci=<optional_camera_id_needed_only_if_video_not_provided> --nc=<optional_maximum_number_of_charts_to_look_for>
- -t=# is the chart type where 0 (Standard), 1 (DigitalSG), 2 (Vinyl)
- –ci=# is the camera ID where 0 (default is the main camera), 1 (secondary camera) etc
- –nc=# By default its values is 1 which means only the best chart will be detected
Examples:
Run a movie on a standard macbeth chart:
/home/opencv/build/bin/example_mcc_chart_detection -t=0 -v=mcc24.mp4
Or run on a vinyl macbeth chart from camera 0:
/home/opencv/build/bin/example_mcc_chart_detection -t=2 --ci=0
Or run on a vinyl macbeth chart, detecting the best 5 charts(Detections can be less than 5 but never more):
/home/opencv/build/bin/example_mcc_chart_detection -t=2 --ci=0 --nc=5
11 const char *about =
"Basic chart detection";
13 "{ help h usage ? | | show this message }" 14 "{t | | chartType: 0-Standard, 1-DigitalSG, 2-Vinyl }" 15 "{v | | Input from video file, if ommited, input comes from camera }" 16 "{ci | 0 | Camera id if input doesnt come from video (-v) }" 17 "{nc | 1 | Maximum number of charts in the image }"};
19 int main(
int argc,
char *argv[])
29 int t = parser.get<
int>(
"t");
34 int camId = parser.get<
int>(
"ci");
35 int nc = parser.get<
int>(
"nc");
38 video = parser.get<
String>(
"v");
50 inputVideo.
open(video);
55 inputVideo.
open(camId);
63 while (inputVideo.
grab())
68 imageCopy = image.
clone();
71 if (!detector->process(image, chartType, nc))
73 printf(
"ChartColor not detected \n");
79 std::vector<Ptr<mcc::CChecker>> checkers = detector->getListColorChecker();
88 imshow(
"image result | q or esc to quit", image);
89 imshow(
"original", imageCopy);
90 char key = (char)
waitKey(waitTime);
std::shared_ptr< _Tp > Ptr
Definition: cvstd_wrapper.hpp:23
void imshow(const String &winname, InputArray mat)
Displays an image in the specified window.
"black box" representation of the file storage associated with a file on disk.
Definition: affine.hpp:51
Designed for command line parsing.
Definition: utility.hpp:799
#define CV_Assert(expr)
Checks a condition at runtime and throws exception if it fails.
Definition: base.hpp:342
Class for video capturing from video files, image sequences or cameras.
Definition: videoio.hpp:666
TYPECHART
enum to hold the type of the checker
Definition: checker_model.hpp:46
virtual bool retrieve(OutputArray image, int flag=0)
Decodes and returns the grabbed video frame.
virtual bool open(const String &filename, int apiPreference=CAP_ANY)
Opens a video file or a capturing device or an IP video stream for video capturing.
virtual bool grab()
Grabs the next frame from video file or capturing device.
std::string String
Definition: cvstd.hpp:150
Mat clone() const CV_NODISCARD
Creates a full copy of the array and the underlying data.
n-dimensional dense array class
Definition: mat.hpp:801
int waitKey(int delay=0)
Waits for a pressed key.
Explanation
Set header and namespaces
using namespace std;
using namespace mcc;
If you want you can set the namespace like the code above.
Create the detector object
Ptr<CCheckerDetector> detector = CCheckerDetector::create();
This is just to create the object.
Run the detector
detector->process(image, chartType);
If the detector successfully detects atleast one chart, it return true otherwise it returns false. In the above given code we print a failure message if no chart were detected. Otherwise if it were successful, the list of colorcharts is stored inside the detector itself, we will see in the next step on how to extract it. By default it will detect atmost one chart, but you can tune the third parameter, nc(maximum number of charts), for detecting more charts.
Get List of ColorCheckers
std::vector<cv::Ptr<mcc::CChecker>> checkers;
detector->getListColorChecker(checkers);
All the colorcheckers that were detected are now stored in the 'checkers' vector.
Draw the colorcheckers back to the image
for(Ptr<mcc::CChecker> checker : checkers)
{
Ptr<CCheckerDraw> cdraw = CCheckerDraw::create(checker);
cdraw->draw(image);
}
Loop through all the checkers one by one and then draw them.