Purple Noise

[Emyr R. E. Pugh]

We were out on a shoot this morning and filmed for about three hours with no problems (Build 21). After packing up the camera and moving to a new location, our 7" LCD began to show strange patches of what looks like purple noise - somewhat like the false color feature, but that's not what it is. Having viewed the Luma Ramp on the Test Signal, four individual bars are now in various shades of purple which is what's presumably causing various shades of gray on our LCD to appear as purple noise.

All the footage we recorded before and after the problem arose is absolutely fine.

We've tried a Black Shading Calibration on Build 21 and then we installed today's new Release Build 30 and did another Black Shading and still the problem remains.

Has anyone run across this before?

 

[Brian Ferguson]

Just a guess if your footage is fine, it is something in your monitoring path.

The Black shading is an overall sensor adjustment. After the sensor the signal is split 2 ways, one to the RAW recording REDCODE and one to the monitoring path.

From what you wrote your Purple Noise is in the RGB monitoring path since you do not see it in your R3D files. Could be a cable or connector, but if it is not in your R3D that is good news - sort of. You may want to try to reset the default settings in System/Maintenance/Restore menu to see if that helps. If it does not then you have narrowed it down more to the LCD, or a cable or connector. Call or email RED tech support to help more.

 

[Emyr R. E. Pugh]

If we were to connect a monitor via HDMI what could we expect to see there? If the noise shows through the HDMI what would that imply. Similarly, if there were no noise off the HDMI what could that signify? Sorry, my brain isn't working after being up for a day and a half.

 

[Emyr R. E. Pugh]

Thanks for the quick reply also.

 

[Deanan]

Can you grab an image off the screen?
How does it look on the recorded image?

 

[Emyr R. E. Pugh]

Ok, so HDMI out is working just fine - that means that the RGB monitor path has a problem outside the camera, i.e. connectors, wires or the LCD unit itself - is that right?

 

[Deanan]

Ok, so HDMI out is working just fine - that means that the RGB monitor path has a problem outside the camera, i.e. connectors, wires or the LCD unit itself - is that right?

Yeah, it sounds like it might be the cable.

 

[Emyr R. E. Pugh]

Deanan, the recorded images are all fine. We've done some more filming tests since the problem arose and we're still getting beautiful footage.

This is what I get on the Luma Ramp:

Then, logically, wherever these shades appear in a given exposure they appear as these four colors, and due to the distribution it looks like false color indicators or 'colored noise'. So, as you zoom, move or adjust the aperture the purple colors move with the shades they have replaced, just like the false color function.

Also, I just noticed the vmCLR at the top of the screen. I can't for the life of me think what this is now. I tried looking it up in the ops guide but the search didn't find anything - what is this indicator trying to tell me?

Thanks again for your input on this.

 

[Deanan]

Deanan, the recorded images are all fine. We've done some more filming tests since the problem arose and we're still getting beautiful footage.

This is what I get on the Luma Ramp:

Then, logically, wherever these shades appear in a given exposure they appear as these four colors, and due to the distribution it looks like false color indicators or 'colored noise'. So, as you zoom, move or adjust the aperture the purple colors move with the shades they have replaced, just like the false color function.

Also, I just noticed the vmCLR at the top of the screen. I can't for the life of me think what this is now. I tried looking it up in the ops guide but the search didn't find anything - what is this indicator trying to tell me?

Thanks again for your input on this.

vmCLR means it's monitoring in REDcolor.

Do you have another monitor cable you can swap with?

 

[Emyr R. E. Pugh]

Do you have another monitor cable you can swap with?

Not at the moment - we might be able to borrow one in the next couple of days though.

My main worry is that this is an LCD problem - is there any possibility that some fault within the LCD unit could be causing this? I'm really hoping it's just the cable and not the connectors on the RED or the LCD.

 

[Stuart English]

LCD display issue.

LCD display issue.

One quick thing that you could try is reversing the LCD interconnect cable.

i.e. unplug it from camera and LCD, flip the cable around, and plug it back in.

Does that make a difference ? Does it feel like you have to force the cable plugs into the camera or LCD's sockets ?

 

[Emyr R. E. Pugh]

One quick thing that you could try is reversing the LCD interconnect cable.

i.e. unplug it from camera and LCD, flip the cable around, and plug it back in.

Does that make a difference ? Does it feel like you have to force the cable plugs into the camera or LCD's sockets ?

Thanks, Stuart - we tried that and had no luck I'm afraid. The monitor socket on the RED body and the LCD socket both feel fine when connecting the cable - no problems at all in terms of ease of connection. I've also checked both ends of the cable for bent pins and the two sockets for any sign of broken pins stuck in the socket, but nothing is broken and nothing is bent as far as I can see. Just to double check I think I'll take some macro shots of the plugs and inspect the maginified image just in case the proximity of the pins might be causing any optical illusions that are tricking me into thinking there isn't a problem, but I've got pretty good sight and everything looks normal to the naked eye.

We're going to try to get a hold of a spare LCD and cable tomorrow. I'll be sure to update the results here just in case anyone else runs into this problem in future.

Thanks everyone for the help and suggestions.

 

[Tom Mitchell]

Well I'm assuming that your not getting this on the EVF just the external red monitor.

do you get the same result from the SDI out and HDMI out, if not it, then it seems to be isolated to just the red monitor

Thus if there was a problem with the cable you could just swap the evf cable and the monitor cable and see if you get the same result.

After testing your cable, then you can only assume that it is the monitor or the video card in the red that is supplying the image to the red monitor, in both cases it would need a ticket and probably be sent back to red.

if you are in the middle of a shoot and cant source a new camera to replace the one your using, you could get in a small HD monitor and take the SDI out and use that as a stop gap.

 

[Emyr R. E. Pugh]

UPDATE: We've received a new LCD cable from RED and using this new cable has no effect and so the purple/pink noise problem is still there.

This has narrowed it down to being something inside the LCD, the LCD port or the port on the RED. It's also worth noting that the problem has since got slightly worse in that five 'bars' on the Luma Ramp have now gone pink (originally it was just four) so that those luma values are now showinng as purple/pink wherever they appear in the image on the LCD screen.

As I said earlier in the post, the camera still works fine otherwise and the footage is not affected by this only the image on the LCD.

The problem we now have is that we can still use the camera and we need to be using it right now, so I was wondering if it would be feasible for us to continue using it for a while (working around this temporary glitch) and then kill two birds with one stone by sending the RED back for servicing at the same time as our MX Upgrade turn comes along?

Can anyone from RED confirm that it's possible to get the camera and LCD serviced/looked at and upgraded at the same time? I'm also hoping that we're not putting the camera at risk by not seeing this problem seen to immediately. Does anyone have any thoughts on this?