I’m processing images inside a for loop with the trigger set to immediate. In the following code:
start(vid);
frame = getdata(vid);
t_total_Start = tic;
for iframe = 1:Nframe
[frame,lT(iframe)] = getdata(vid);
snapshotbuffer(:,:,iframe) = frame;
hvpc.step(frame);
end

release(hvpc);
elapsedTime = toc(t_total_Start);
timePerFrame = elapsedTime / iframe
effectiveFrameRate = 1 / timePerFrame
The effective frame rate approximately ~450 FPS.
After adding a few functions into the for loop:
start(vid);
frame = getdata(vid);
t_total_Start = tic;
for iframe = 1:Nframe
[frame,lT(iframe)] = getdata(vid);
snapshotbuffer(:,:,iframe) = frame;
% Two functions used to process the frame
function1(frame);
function2(frame);

hvpc.step(frame);
end
release(hvpc);
elapsedTime = toc(t_total_Start);
timePerFrame = elapsedTime / iframe
effectiveFrameRate = 1 / timePerFrame
The effective frame rate is still around 450 FPS, but I expected it to drop because function1 and function2 are now inside the loop. I measured their execution time using tictoc, and they take about 0.5 ms together, so the frame rate should drop to around 370 FPS (1/(1/450 + 0.5e-3) = 370 FPS).
I also tested by replacing function1 and function2 with pause(0.0005), but the frame rate still didn’t drop. I’m wondering why the frame rate isn’t decreasing as expected.
I have another question about timing. Is getdata providing the correct timestamps after adding functions inside the loop? Should I use tic and toc to measure the time for each frame? The timestamps from getdata don’t seem to change, even when I add a pause in the loop.
Thanks!I’m processing images inside a for loop with the trigger set to immediate. In the following code:
start(vid);
frame = getdata(vid);
t_total_Start = tic;
for iframe = 1:Nframe
[frame,lT(iframe)] = getdata(vid);
snapshotbuffer(:,:,iframe) = frame;
hvpc.step(frame);
end

release(hvpc);
elapsedTime = toc(t_total_Start);
timePerFrame = elapsedTime / iframe
effectiveFrameRate = 1 / timePerFrame
The effective frame rate approximately ~450 FPS.
After adding a few functions into the for loop:
start(vid);
frame = getdata(vid);
t_total_Start = tic;
for iframe = 1:Nframe
[frame,lT(iframe)] = getdata(vid);
snapshotbuffer(:,:,iframe) = frame;
% Two functions used to process the frame
function1(frame);
function2(frame);

hvpc.step(frame);
end
release(hvpc);
elapsedTime = toc(t_total_Start);
timePerFrame = elapsedTime / iframe
effectiveFrameRate = 1 / timePerFrame
The effective frame rate is still around 450 FPS, but I expected it to drop because function1 and function2 are now inside the loop. I measured their execution time using tictoc, and they take about 0.5 ms together, so the frame rate should drop to around 370 FPS (1/(1/450 + 0.5e-3) = 370 FPS).
I also tested by replacing function1 and function2 with pause(0.0005), but the frame rate still didn’t drop. I’m wondering why the frame rate isn’t decreasing as expected.
I have another question about timing. Is getdata providing the correct timestamps after adding functions inside the loop? Should I use tic and toc to measure the time for each frame? The timestamps from getdata don’t seem to change, even when I add a pause in the loop.
Thanks! I’m processing images inside a for loop with the trigger set to immediate. In the following code:
start(vid);
frame = getdata(vid);
t_total_Start = tic;
for iframe = 1:Nframe
[frame,lT(iframe)] = getdata(vid);
snapshotbuffer(:,:,iframe) = frame;
hvpc.step(frame);
end

release(hvpc);
elapsedTime = toc(t_total_Start);
timePerFrame = elapsedTime / iframe
effectiveFrameRate = 1 / timePerFrame
The effective frame rate approximately ~450 FPS.
After adding a few functions into the for loop:
start(vid);
frame = getdata(vid);
t_total_Start = tic;
for iframe = 1:Nframe
[frame,lT(iframe)] = getdata(vid);
snapshotbuffer(:,:,iframe) = frame;
% Two functions used to process the frame
function1(frame);
function2(frame);

hvpc.step(frame);
end
release(hvpc);
elapsedTime = toc(t_total_Start);
timePerFrame = elapsedTime / iframe
effectiveFrameRate = 1 / timePerFrame
The effective frame rate is still around 450 FPS, but I expected it to drop because function1 and function2 are now inside the loop. I measured their execution time using tictoc, and they take about 0.5 ms together, so the frame rate should drop to around 370 FPS (1/(1/450 + 0.5e-3) = 370 FPS).
I also tested by replacing function1 and function2 with pause(0.0005), but the frame rate still didn’t drop. I’m wondering why the frame rate isn’t decreasing as expected.
I have another question about timing. Is getdata providing the correct timestamps after adding functions inside the loop? Should I use tic and toc to measure the time for each frame? The timestamps from getdata don’t seem to change, even when I add a pause in the loop.
Thanks! image-processing, image acquisition MATLAB Answers — New Questions

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