Noise in progressive video (esp. in shadows)?

ajalali

ajalali

Active member
Hi folks - I've been testing out my new dvx100a over the last couple of days. I am really impressed with this camera overall -- the 24p and 30p progressive modes look really nice on TV, but I am noticing quite a bit more grain on the Panasonic vs. my old Sony TRV900. I read somewhere that Panasonic states the progressive modes have 6dB worse S/N ratio vs. interlaced modes -- anyone else heard this too?

Below I've attached two frame grabs - one from my dvx100a, and one from my older TRV900. Please excuse the composition/color of the pics (and the aspect ratio problems) -- I was only trying to compare the noise level of the Panasonic (progressive) to my old Sony (interlaced). It's a little difficult to see on your computer monitor, but notice the graniness of the Panasonic, especially in the shadows of the picture vs. the Sony:

Here's the Panasonic dvx100a framegrab:
191092552.jpg


And here's the Sony:
191092656.jpg


On a 36" JVC TV (connected via S-Video), there was clearly more noise in the dark parts of the Panasonic's progressive video vs. the old Sony's interlaced video. Any comments on the noise levels?

Also I've noticed that in darker parts of the picture (shadows), progressive video from the DVX often has slight blue/purple noise present (even at 0dB gain). At 6dB gain you can clearly see this "chroma" noise. Seems that the CineGamma_D mode tends to increase this "chroma" noise vs. the plain "CineGamma" mode. I worry because the CineGamma_D mode would be very useful for getting more detail out of the shadows if it wasn't noisy. Has anyone else noticed this in their progressive video? Is there some CCD defect to watch out for in these dvx100a's?

Thanks for your help.
 
Re: Noise in progressive video (esp. in shadows)?

Can you do this for me?

Set up your cameras side by side.

Place a white item and a black item side by and light the scene so that the white item causes the auto iris to hit 5.6.

Shoot a few seconds of each onto DV tape.

Take the DV footage and run it into your computer.

Export one frame from each clip. Take those frames and put them in photoshop.

Cut out a 100 x 100 pixel square from each dark portion in photoshop and save those portions as TIFF files.

Send the files to me at snjackson at mindspring dot com.

Doing this is a way to normalize as much as possible the two images so that they can be put onto a scope, and compared minutely in photoshop. If you were really gung ho, you could could count pixels which varied a set degree from the norm (which would indicate noise) and discuss which one had a really different noise. What you are trying to do in any case is try and eliminate things like the cameras handling light better or worse (3CCD cameras need more light to get a clean shot) and personal bias (not political, but in how you see images artistically).
 
Re: Noise in progressive video (esp. in shadows)?

Slapdragon - thanks for the feedback - I will try to do the test you describe and e-mail you the pics this evening or tomorrow. Your test sounds like a good way of removing operator "bias" from the comparison.

I'll try to take a frame grab from both interlaced and progressive video on the DVX, and a frame from the TRV900's interlaced video, so that all 3 can be compared. When I grab a frame in Vegas, my only options are save to PNG or JPEG, so I will save PNG, and then in Photoshop I will save the small 100x100 square as a TIFF.

The DVX picture is really top-notch on color rendition, but it seems to exhibit a little more chroma noise (especially in progressive mode) than my old Sony TRV900. Adding gain on the DVX greatly increases this chroma noise, while on the TRV900 gain simply seems to increase the overall picture noise.
 
Re: Noise in progressive video (esp. in shadows)?

[quote author=AJ link=board=Events;num=1089478203;start=0#2 date=07/10/04 at 12:01:26]Slapdragon - thanks for the feedback - I will try to do the test you describe and e-mail you the pics this evening or tomorrow.  Your test sounds like a good way of removing operator "bias" from the comparison.

I'll try to take a frame grab from both interlaced and progressive video on the DVX, and a frame from the TRV900's interlaced video, so that all 3 can be compared.  When I grab a frame in Vegas, my only options are save to PNG or JPEG, so I will save PNG, and then in Photoshop I will save the small 100x100 square as a TIFF.

The DVX picture is really top-notch on color rendition, but it seems to exhibit a little more chroma noise (especially in progressive mode) than my old Sony TRV900.  Adding gain on the DVX greatly increases this chroma noise, while on the TRV900 gain simply seems to increase the overall picture noise.[/quote]

Keep it PNG and make it 24 bit into and out of photoshop. However, it might be better if you send me a 2 frame grab from each clip in the original DV, as I can examine it in the original NTSC color space, which we cannot do even in TIFF. Name them 1.dv, 2.dv, and 3.dv and I will strip the images out in the 4:1:1 color space and then look at it there.
 
Re: Noise in progressive video (esp. in shadows)?

You're definitely right with regards to gain and chroma noise.  I rarely (if ever) use more than +3db of gain on my DVX100A.  The Sony's definitely gain up cleaner and are brighter in low light.  However, I find they start losing their color tone as they gain up.  I always try and light appropriately with my DVX.  This is exactly why I have always maintained that for someone that relies on gain (such as a wedding videographer) and constantly shoots in fairly low light, the Sony cameras seem to work better (maybe easier is a better word).

I mix my Sony's and DVX quite often, but never without proper light.  The trade off is (IMO) when exposed properly, the DVX has a wonderful look that I wouldn't trade and the camera is infinitely tweakable.  I guess it just depends on your environment and what you ultimately plan to shoot predominately.

Andrew
Crystal Clear Media
 
Re: Noise in progressive video (esp. in shadows)?

Andrew - Thanks for the reply. Yes I've noticed that the Sony gain is cleaner than the DVX100A's. However it seems to me that even at 0dB gain, my DVX100A's picture is noisier than the Sony's picture! This is especially true in shadows (i.e. outside on a sunny day) where the chroma noise seems significantly higher, and is a bit disconcerting because it means that even with proper lighting I have to watch out for noise in shadows.

Also, I find that the Cine-Like_D gamma mode is noisier than the Cine-Like gamma mode. Seems like the "D" mode gives you more exposure latitude (stops) by increasing the gain (and thereby noise) in dark parts of the picture. The "Cinelike" Matrix mode also seems noisier than the "Normal" Matrix mode!

Does this all seem typical of this camera, or do you think I have some defective CCD's?

Thanks
 
Re: Noise in progressive video (esp. in shadows)?

[quote author=Slapdragon link=board=Events;num=1089478203;start=0#1 date=07/10/04 at 10:06:49]Can you do this for me?  

Set up your cameras side by side.

Place a white item and a black item side by and light the scene so that the white item causes the auto iris to hit 5.6.

Shoot a few seconds of each onto DV tape.

[/quote]

Slapdragon - I sent you the pics. Check your e-mail when you get the chance. Thanks!
 
Re: Noise in progressive video (esp. in shadows)?

Hey, can't we all see 'em?

I certainly find a lot of noisiness with the DVX at 0dB gain, most noticeable in reddish wood. Big, chunky, blocky noise....
 
Re: Noise in progressive video (esp. in shadows)?

Ullanta - sorry I had many pics & they were +100Kb each, so I didn't think I should upload here. I will try to compress down a few of them (below 100Kb) and post here later. They weren't exactly the most interesting pics though...

Regarding the noise in reddish wood - YES that is exactly what I see. Also reddish-brown leather is quite noisy at low light levels. And sometimes I see bright blue chroma noise in black areas of my picture! I've heard that this could be due to improper white balance, so I'm still testing...

Anyway, do you know of any "work-arounds" for the chroma noise in reddish wood?

Thanks.
 
Re: Noise in progressive video (esp. in shadows)?

No, unfortunately... lowering detail level can help a tiny bit, but the whole image suffers more than it's worth. Basically, when possible, lighting is the best thing. I don't remember such noticeable trouble in the darker shadows and blacks; it's usually in very low midrange areas. So, brightening the subject and darkening the woody background helps.

Also, in general this noise doesn't show up in the LCD... a CRT monitor is essential for avoiding this. I have a really crappy 8" monitor that doesn't calibrate correctly, which I got for $75... it's useless for almost everyhing but works well for this "noise' detection in the field...
 
Re: Noise in progressive video (esp. in shadows)?

I own a pal dvx100a and I use the cinev quite alot as I like the punchy image as opposed to the muddiness of cine D and definitely notice grain in the blacks and dark greens under GOOD light not just low light.
Solutions? unsure. Its a problem in weddings where all the guys usually wear black suits. Coring doesnt seem to change much. I minimize by using norm matrix, push the colour temperature to the orange side( as blues/ black are touchy ) decrease saturation by decreasing chroma level and increase the pedestal to crush the blacks abit. This obviously changes the rest of the image significantly but the only other way is to avoid cinev and d and use standard cine.
 
Re: Noise in progressive video (esp. in shadows)?

Was the footage shot on manual or auto white balance?
I have found the manual WB to exhibit much less noise in darker areas/low light....especially shooting darker wood furniture.
FWIW,

Brian Broz
 
Re: Noise in progressive video (esp. in shadows)?

Make sure that you are not using the LCD screen to represnt your noise. I have noticed that the LCD screen is 10x noisier than the acual footage when displayed on my monitor or my NTSC monitor.
 
Re: Noise in progressive video (esp. in shadows)?

[quote author=scharky link=board=Events;num=1089478203;start=0#12 date=07/12/04 at 18:40:43]Make sure that you are not using the LCD screen to represnt your noise.  I have noticed that the LCD screen is 10x noisier than the acual footage when displayed on my monitor or my NTSC monitor.[/quote]

Weird... I find the opposite. The color noise I see is often not visible in LCD (or LCD computer monitor), but glaring on an NTSC CRT. For this reason I drag a monitor around whenever possible...
 
Re: Noise in progressive video (esp. in shadows)?

Brian Broz - yes I did manual white balance before shooting the wood. I also have seen that in certain conditions manual white balance reduces the "chroma noise" in the picture.

Scharky / ullanta - I have to agree with ullanta on the LCD noise issue... while the LCD is definitely "noiser" overall than a CRT monitor, I usually can NOT see the "chroma noise" I'm referring to on the camera's LCD or EVF. That's a bummer because sometimes you just can't drag a monitor to your shooting location.

Try this to see the "chroma noise" I'm referring to: In a low-lit room, first manual white balance then zoom into a black object in the room. Make sure you are in 24p mode, using cinegamma and cine-like matrix. Set your gain to 0dB. Take some footage. Also take some footage with the gain at 6dB and 12dB. Next, change your matrix to normal and take the same footage.

Play your footage back on a TV. 2 observations: You probably will see blue chroma noise on the black object. At 6dB you can see the blue noise well, and at 12dB the blue chroma noise is strong! I've found that changing the matrix setting to normal reduces this blue chroma noise significantly (especially at 12dB). Do you guys see this blue noise, and the difference between normal and cine-like matrix with your cameras?
 
Re: Noise in progressive video (esp. in shadows)?

It's fully normal that chroma noise is Matrix setting dependent: "matrix" is nothing more than a selective saturation setting. If the matrix setting pushes the bleu chroma (color difference signals ) level, the blue channel will become more noisy. The noise relates to the lower sensitivity of the blue CCD (photodiode) structure, resulting in a lower S/N ratio for blue. Coring acts on the luma signals and will not significantly change (blue) chroma noise.
 
Re: Noise in progressive video (esp. in shadows)?

yep !

that's it.

DVFilm recommends to use normal chroma matrix for film transfer probably to minimize chroma noise, and i think it is a wise decision.

If you want the same (about the same) imagery as cinelike color matrix but with a MUCH cleaner overall image, then use normal chroma matrix, dial +4 chroma level and +3 chroma phase (to compensate).

BANG !  much cleaner.
 
Re: Noise in progressive video (esp. in shadows)?

I have read this thread and I agree there is a good bit of noise in shadows of 24p outdoor shots. I find it so objectionable that I can't be happy with using them. Is there any solution? I use preset white balance.
 
Re: Noise in progressive video (esp. in shadows)?

I can't say I've noticed any noise in any shadow areas at all, ever... :-/
 
Re: Noise in progressive video (esp. in shadows)?

I too have never noticed noise in outside shadows, and I just shot 3hrs of footage at a very bright and sunny outdoor wedding, one with the dvx100a and one dvc80. The dvx was shooting at 24pn and the dvc80 was color matched to the dvx. The saturation and color levels are almost identical and neither has any noise in the groom/groomsman's dark suits, nor in any shadows of the nearby trees. If you are getting noise in the shadows then something is not set right. YOu might want to do some tests outside with different gamma/pedestal settings and see what you get.
I also had a lot of night shots lit only by an on camera 35watt SV light. None of those shots had any noise in the shadows either.
 
You must log in or register to reply here.
Back
Top