I have a weather web cam which uploads outdoor pictures every 5 minutes. I have been struggling with a problem with the web cam images displaying rows of black or gray pixels starting at the bottom of the image. This corruption waxed and waned throughout the day, sometimes consuming large portions of the picture.
I have spent hours searching the web for an answer. I have read countless articles and forum postings without success. I have noticed that many others have the same problem, with no answer to be found.
I am posting this to share a solution to the problem which I discovered through trial and error. I hope it will help someone else struggling with this frustrating issue.
First, when playing with the web cam settings I noticed that the corruption increased with the sharpness of the image. It seemed the more detailed the picture, the more likely a problem would occur. So for some of you, if this problem is minor, that is, it occurs intermittently or only involves a few rows of pixels, you may be able to correct it by simply lowering the sharpness setting. Yes, this will result in a less detailed picture. You decide which bothers you more.
For others who are experiencing a large amount of corruption of the image, which may obliterate most of the picture, I have found that reducing the image resolution has worked to end the problem. I was reluctant to change from the default settings but the problem has not returned since I tried it.
Yes, it makes the picture smaller or grainier when enlarged however I was able to increase the sharpness setting without the problem reappearing.
This is not a perfect solution. Other factors which may be involved include a cheap web cam with a fairly low resolution to start with. Spending a few extra bucks on a decent web cam may allow you to lower the resolution without loosing much detail in the image.
Another problem can be the distance from your web cam to the computer processing the image. USB cables will degrade the signal if the distance is longer than 15 feet without a repeater or external power supply, so check the length of your cable. Shorter is better.
Let me know if this worked for you or if you found another solution. Good Luck with your project.