calculating average lumination of a frame in a video clip

[shebin]

I am working out to calculate the averageluma of certain frames in a video clip to pointout blank frames, but with no idea how to go about it.
Can anyone help with suggestions and ideas how to do it?? If not can anyone direct me where I could find a solution?

[Moschops]

What is luma a property of? I'm presuming it's a property of each individual pixel.

In which case, sum the luma values of all the pixels in the frame, and then divide by the number of pixels in the frame.

[shebin]

Thanks Moschops..

My requirement is to identify a blank frame in a video clip, When I was googling I found the Averageluma() method in AVsynth which outputs 16 for blank frames.
Moschops can you please explain me how to go about with the point you stated, I will be thankfull if you could explain step by step. Also please suggest me where can I find some code samples for the above

[Moschops]

Are you able to extract each frame into your code and examine the luma value of each pixel in that frame?

[shebin]

My application is a video player built from an sdk, using the getFrame() method I am able to extract frames, now how can i calculate values of each pixel.
my exact work is to identify blank frames to mark commercials from a tv recording. and extract these commercials. Most broadcast insert blank frames at the begining and at the end of the commercials.

Thanks for your reply


Moschops where can I find sample c++ codes related to video handling?

[Moschops]

All I would do is google sample code, and you can look that up yourself.

If you can get the value of luma for each pixel, this is the code you need:

int lumasum = 0;
for (int x=0; x < imageWidth; x++)
{
  for (int y=0; y < imageHeight; y++)
  {
     int lumaOfThisPixel = getLumaOfPixel(x,y);
     lumasum = lumasum + lumaOfThisPixel;
  }
}
int averageLuma = lumasum / (imageWidth * imageHeight);

Here is how to calculate luma from RGB values.

http://en.wikipedia.org/wiki/Luma_%28video%29

[shebin]

Thanks Moschops Thanks Very much
Let me try this out and learn more about this and come back with more of my doubts

Once again thanks