Robin,
I've noticed that when Feature Tracking (Camera ROI/Centrer of Mass on Venus) I get a strange spike in the histogram curve at about 68%. It is not always there and flicks in and out every few seconds. If I stop feature tracking then the histogram is normal.
Screen shots attached during tracking and without tracking.
Is this by design or a bug ?
Thanks,
Mike
Histogram spike when Feature Tracking
Histogram spike when Feature Tracking
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- SPIKE 2023-05-20 20_03_25-SharpCap Pro (v4.1.10561, 64 bit) - ZWO ASI1600MM Pro (051D920511080900, via USB.png (150.58 KiB) Viewed 445 times
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- NO SPIKE 2023-05-20 20_04_24-SharpCap Pro (v4.1.10561, 64 bit) - ZWO ASI1600MM Pro (051D920511080900, via USB.png (176.29 KiB) Viewed 445 times
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Re: Histogram spike when Feature Tracking
Hi Mike,
I think it is a little bug - not really deliberate but it shouldn't cause any other problems.
I'm fairly sure that what is happening is that the histogram is measuring the brightness levels after the cross indication for the center of mass is drawn onto the frame, so the pixels that are changed to draw the cross are causing the spike in the histogram.
However, saved frames should not show the cross in them and therefore are unaffected by this.
I have a slowly progressing project of changing things so that indications like the center cross and others are drawn only on the screen rather than having to be added to a copy of the frame image as it passes through SharpCap. Unfortunately there is a lot of code that still works the old way.
cheers,
Robin
I think it is a little bug - not really deliberate but it shouldn't cause any other problems.
I'm fairly sure that what is happening is that the histogram is measuring the brightness levels after the cross indication for the center of mass is drawn onto the frame, so the pixels that are changed to draw the cross are causing the spike in the histogram.
However, saved frames should not show the cross in them and therefore are unaffected by this.
I have a slowly progressing project of changing things so that indications like the center cross and others are drawn only on the screen rather than having to be added to a copy of the frame image as it passes through SharpCap. Unfortunately there is a lot of code that still works the old way.
cheers,
Robin
Re: Histogram spike when Feature Tracking
Thanks Robin,
After posting my question I was coming to the same conclusion that the historgram was showing the pixels used to draw the cross. As you say it does not affect the saved frames in any way.
I guess the follow on question is why the cross is flickering between frames i.e. a good proportion do not seem to be detecting the object and drawing the cross. I'll have to do some more experimentation with the background and contrast selection boxes.
All the best,
Mike
After posting my question I was coming to the same conclusion that the historgram was showing the pixels used to draw the cross. As you say it does not affect the saved frames in any way.
I guess the follow on question is why the cross is flickering between frames i.e. a good proportion do not seem to be detecting the object and drawing the cross. I'll have to do some more experimentation with the background and contrast selection boxes.
All the best,
Mike
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admin
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Re: Histogram spike when Feature Tracking
Hi Mike,
well, the code to calculate the center position only picks (at most) one frame every 0.25s to process, but it should add the cross to all the frames just before they are displayed (subject to a couple of other logical checks - maybe those are failing somehow).
I will have an experiment myself to see if I can work out why it flickers.
cheers,
Robin
well, the code to calculate the center position only picks (at most) one frame every 0.25s to process, but it should add the cross to all the frames just before they are displayed (subject to a couple of other logical checks - maybe those are failing somehow).
I will have an experiment myself to see if I can work out why it flickers.
cheers,
Robin