colour pixels at night

[brihunnikin 0]

hi guys.

i have got a site that has that has 16 cameras 10 of these are old jvc colour body cameras and with in 1 week 5 of these have developed coloured pixels scattered across the image only of a night time. the lighting conditions have not change and all these 10 cameras are off the 1 power supply???

 

any ideas

 

many thanks Brian

[Soundy 1]

Can you provide screenshots or stills of this effect? It's not uncommon for day/night cameras to switch to night mode and DVRs to show color artifacts in the B&W video.

[Squiffy 0]

Sounds like dead pixels to me

[brihunnikin 0]

Can you provide screenshots or stills of this effect? It's not uncommon for day/night cameras to switch to night mode and DVRs to show color artifacts in the B&W video.

 

 

here are the stills

[ryeporta 0]

Can you provide screenshots or stills of this effect? It's not uncommon for day/night cameras to switch to night mode and DVRs to show color artifacts in the B&W video.

 

 

Hi Soundy .. this sounded complicating to me .. what do you mean by "color artifacts in the B&W video"

[Soundy 1]

Can you provide screenshots or stills of this effect? It's not uncommon for day/night cameras to switch to night mode and DVRs to show color artifacts in the B&W video.

 

 

Hi Soundy .. this sounded complicating to me .. what do you mean by "color artifacts in the B&W video"

 

Briefly, when most DVRs display a B&W camera on a color channel, you'll see shifting color patterns on the image. This is a side-effect of color processing on greyscale vide, since greyscale video is still comprised of all three colors (red, green and blue), just all in equal amounts.

 

With "lossy" video codecs (as with lossy image codecs, like JPEG), the image is examined and small variations in color are discarded - for example, an area with several very close shades of blue may be stored as just a single shade of blue, to save storage space.

 

When you get shifting noise or lighting patterns in greyscale, that color processing can get "confused" and substitute full colors - say the brightness increases slightly between the time it processes the red and the blue components. Where the colors are actually balanced, the processor sees that there's more blue than red, so it will toss the red data and store the blue. When you view the compressed video, then, it shows that area as blue, rather than greyscale.

 

You can see some examples in the gates at the top of this picture:

 

The fix (or workaround, in some cases) is to zero the "Saturation" setting(s) for the B&W cameras. Some also have an option to simply tell the system that that camera is B&W or greyscale.

[ryeporta 0]

Hi Soundy .. thanks for the illustration