Hi, I'm working on a project based on real time image processing using CImg Library in Raspberrypi.

I need to capture images at higher frame rates (say atleast 30 fps), when I use the inbuilt Raspicam commands such as

sudo raspistill -o -img_%d.jpg -tl 5 -t 1000 -a 512

/* -tl : time lapse duration in msec

-t : total time duration (1000 msec = 1 sec)

-a : displays frame numbers

*/

with this command though it shows 34 frames per second,I could only capture maximum of 4 frames/images (and rest of the frames are skipped)

sudo raspistill -o -img_%d.jpg -tl 5 -tl 1000 -q 5 -md 7 -w 640 -h 480 -a 512

and From this above command I could capture at a maximum of 7-8 images per second but by reducing the resolution and quality of the images.

But I don't want to compromise on the quality of an image since I will be capturing an image, processing it immediately and will be deleting an image to save memory.

Later I tried using V4L2(Video for Linux) drivers to make use of the best performance of a camera, but in the internet, tutorials regarding V4l2 and cimg are quite scarce, I couldn't find one.

I have been using the following commands

# Capture a JPEG image

v4l2-ctl --set-fmt-video=width=2592,height=1944,pixelformat=3

v4l2-ctl --stream-mmap=3 --stream-count=1 –stream-to=somefile.jpg

(source : http://www.geeetech.com/wiki/index.php/Raspberry_Pi_Camera_Module)

but I couldn't get enough information about those parameters such as (stream-mmap & stream-count) what does it exactly, and how does these commands help me in capturing 30 frames/images per second ?

**CONDITIONS:**

1. Most importantly I don't want to use OPENCV, MATLAB or any other image processing softwares, since my image processing task is very simple (I.e detection of led light blink) also my objective is to have a light weight tool to perform these operations at the cost of higher performance.

2. And also my programming code should be in either C or C++ but not in python or Java (since processing speed matters !)

3. Please make a note that,my aim is not to record a video but to capture as many frames as possible and to process each and individual images.

For using in Cimg I searched over few docs from a reference manual, but I couldn't understand it clearly how to use it for my purpose.

The class cimg_library::CImgList represents lists of cimg_library::CImg images. It can be used for instance to store different frames of an image sequence.

(source : http://cimg.eu/reference/group__cimg__overview.html )

* I found the following examples, But i'm not quite sure whether it suits my task

Load a list from a YUV image sequence file.

CImg& load_yuv

(

const char *const 

filename,

const unsigned int 

size_x,

const unsigned int 

size_y,

const unsigned int 

first_frame = 0,

const unsigned int 

last_frame = ~0U,

const unsigned int 

step_frame = 1,

const bool 

yuv2rgb = true 

Parameters filename

Filename to read data from.

size_x

Width of the images.

size_y

Height of the images.

first_frame

Index of first image frame to read.

last_frame

Index of last image frame to read.

step_frame

Step applied between each frame.

yuv2rgb

Apply YUV to RGB transformation during reading.

But here, I need rgb values from an image frames directly without compression.

Now I have the following code in OpenCv which performs my task, but I request you to help me in implementing the same using CImg libraries (which is in C++) or any other light weight libraries or something with v4l2

#include

#include

using namespace std;

using namespace cv;

int main (){

VideoCapture capture (0); //Since you have your device at /dev/video0

/* You can edit the capture properties with "capture.set (property, value);" or in the driver with "v4l2-ctl --set-ctrl=auto_exposure=1"*/

waitKey (200); //Wait 200 ms to ensure the device is open

Mat frame; // create Matrix where the new frame will be stored

if (capture.isOpened()){

while (true){

capture >> frame; //Put the new image in the Matrix

imshow ("Image", frame); //function to show the image in the screen

}

}

}

}

`

* I'm a beginner to the Programming and Raspberry pi, please excuse if there are any mistakes in the above problem statements.

Awaiting your favorable suggestions and any help is really appreciated.

Thanks in advance

Best Regards

BLV Lohith Kumar