how select a frame from video and calculate its RBG value for watermark project

Hi everyone, i'm a newbie to Matlab and i'm facing problem with it. I'm working on implementing a watermark algorithm for videos based on compressive sensing domain. i need to calculate the RGB value of each frame being read and then compare it to a pre-defined threshold. if it is greater than or equal to the threshold then i can embed the watermark text in a randomly selected sub-block of the frame. one more question, i run my initial code and i got this error:

Expected outputformat to match one of these strings:

'native', 'default'

The input did not match any of the valid strings.

the line which caused this error is:

for k =1:1: nFrames
    mov(1).cdata =readFrame(v,k); 
    im = mov(1).cdata; 
    [r ,c, d ] = size (im); 
    if (1==1)
        im (r, c, d ) = length (a);
    else
        try
            im (r, c, d) = a(1-1);
        end
    end

end

any help will be much appreciated!

[cao Huynh]

hello sir!

can u solve this problemm ?

[Image Analyst]

He accepted the answer so I guess he looked over my demo and figured out how to do it. Anyway, this was 7 years ago so I'm sure he wouldn't need it solved anymore if he hadn't gotten it solved by now.

If you have a simialr problem, and aren't able to adapt my demo to process your video, then read this first:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

and post your m-file in a new question of your own (not here).

Answer 1

[Image Analyst]

See my demo where I read in a video and "calculate the RGB value of each frame being read".

Your code is non-functional for several reasons, like the badly-named "a" not being defined, testing for the condition 1==1, using an index of (1-1) on an undefined array, etc. Just scrap that code and try to adapt mine, which is much more robust.

[Shahad]

thank you so much for this helpful tutorial! if i need any more help, i will send you if that's not a bother to you.