How to sum up about 3-4 color frames and only show the brightest frame. Matlab
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Marqual Brown
on 27 Sep 2017
Commented: Walter Roberson
on 29 Sep 2017
obj = VideoReader('C:\Users\Robotics\Pictures\Saved Pictures\Lightfile\Prelight.MOV');
for img = 1:obj.NumberOfFrames;
filename = strcat('frame',num2str(img),'.jpg');
b = read(obj,img);
imwrite(b,filename);
end
I have this code that reads the file and get all frames, but I need it to sum up about 3-5 frames then take the brightest frame and store it. Can someone help please!!
2 Comments
OCDER
on 27 Sep 2017
Edited: OCDER
on 27 Sep 2017
Can you explain what you mean to "sum up 3-5 frames and take the brightest frame"? The sum of 3-5 frames will always be the brightest frame.
Since an image is a matrix, you can simply add images together using matrix math, but use double format (im2double) so that the sum of 3-5 images doesn't exceed the maximum value given a number format (ex: uint8 max value is 255). Rescale all image intensities at the end to prevent flickering effects by inconsistent rescaling.
Accepted Answer
Walter Roberson
on 27 Sep 2017
Edited: Walter Roberson
on 28 Sep 2017
The below code assumes that the frames are RGB.
The below code does not attempt to detect intervals of flash and determine the best out of the interval: it takes the frames frames_per_group at a time and determines the brightest of that group.
obj = VideoReader('C:\Users\Robotics\Pictures\Saved Pictures\Lightfile\Prelight.MOV');
frameidx = 0;
frames_per_group = 5;
frame_history = [];
frameidx_history = [];
while hasFrame(obj)
frameidx = frameidx + 1;
groupidx = groupidx + 1;
b = readFrame(obj);
frame_history = cat(4, frame_history, b);
frameidx_history(end+1) = frameidx;
if size(frame_history, 4) == frames_per_group
maxbrightness = -inf;
maxbrightnessidx = -inf;
for K = 1 : frame_per_group;
grayframe = rgb2gray(frame_history(:,:,:,K));
thisbrightness = sum(grayframe(:));
if thisbrightness > maxbrightness
maxbrightness = thisbrightness;
maxbrightnessidx = K;
end
end
bestframe = frame_history(:,:,:,maxbrightnessidx);
bestframeidx = frameidx_history(maxbrightnessidx);
filename = sprintf('frame%04d.jpg', bestframeidx);
imwrite(bestframe, filename);
frame_history = [];
frameidx_history = [];
end
end
(Code not tested)
8 Comments
Walter Roberson
on 29 Sep 2017
I do not know how a 360 degree camera might differ from a regular camera ? Is it just like a fish-eye lens with a single image, or is it multiple images at the same time?
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