AF100 Highlight Clipping Problems

[Glenn Przyborski]

I've experienced a bit of a problem with how my AF100 clips to white. In bright areas of a scene, the camera soft clips the luminescent portion of the image before the chroma signal is clipped. This yields some very undesirable colored highlights.

For example, if you're shooting a scene with a bright background, and normally exposed foreground talent, the overexposed portions of the BG might be intense teal or blue rather than white. In other words, chroma output level doesn't track with luminescent output level as the camera approaches white clip.

Viewing the live HDSDI signal on a Leader LV7700 HD rasterizer confirms this situation. The adjustable knee settings work perfectly on the luminescent portion of a bright scene, but the chroma level doesn't back off the same amount as you approach clipping. (The AF100 hard clips its luminescent signal at 110 units of video. At clipping, it's possible to have colorful objects in the scene that are completely off-scale.) During editing you should definitely "legalize" the AF100's video before sending your work to a broadcast TV facility.

Unfortunately there are no menu driven controls to set the AF100's soft or hard clip levels. More than likely, this portion of the camera's settings are accessed via a setup program using the USB port or possibly through firmware. Unless Panasonic addresses this situation, the only solution is to be cognizant of what may happen to the look of certain over-exposed portions of your scene. You can also help minimize the problem by making sure your white balance is set properly. If a scene has controlled lighting, the AF100 looks as good as any camera on the market... including ones that cost 10x more.

 

[PaPa]

I do a few things

1) Make sure my white balance is spot on
2) Use lower saturation in camera to ease the chroma clipping
3) Use a little highlight de-saturation or 3-way color correct on the highlights to pull them back to a proper color
4) Use an S curve to smooth out the clip transition.

All of this works very well. I no longer worry about clipping cause sometimes I want things to clip and i know i can have them look pleasing when it gets to post.

Would be wonderful to think panasonic may release a firmware to help alleviate this, but something tells me that's just wishful thinking.

 

[kylekmd]

I agree, Papa.

I've been using the Zuikos which communicate with the camera, showing exposure info on the display. This is very helpful and allows me to reign in the highlights when necessary, without any problem.

Consequently, I have not had any problems with highlight clipping, and don't see this as an issue with this camera despite the huge concern early on.

 

[Mac]

I'm disappointed to hear that this clipping issue is much the same as on the 200 and 500 cameras. The only thing I've disliked about the picture from the HPX500 is the chroma/luma clipping disparity. Otherwise I still don't have a problem with the codec or the resolution... I had hoped that with the AF100 Panasonic would have found a way around this problem

 

[Noel Evans]

Unfortunately there are no menu driven controls to set the AF100's soft or hard clip levels.

Not in that sense but the knee determines where highlights will start to rolloff.

This plus a few notches down on chroma (as Papa mentioned) and about a half stop underexposure work well for me. Had the same thing on my HPX500 and never bothered me in more than a handful of situations over a long period with the right settings and control.

 

[Dino]

AF100 is no better or no worse than HVX200/200A/HPX170/500 with chroma clipping. It's a shame it hasn't been addressed since the HVX200 in 2004. Lumix GH1 and GH2 don't seem to have the issue, so why can't the AG video division get a handle on it? AJ cameras, with higher bit DSP's don't have it, but GH1/2 must be doing something right with lower-end DSP's? No question proper RB gain balance and a more neutral matrix and reduction of chroma gain can help some.

 

[Steve Kahn]

Lumix GH1 and GH2 don't seem to have the issue, so why can't the AG video division get a handle on it?

That's why I wonder why this can't be fixed via firmware.

 

[Marc Villafan]

That's why I wonder why this can't be fixed via firmware.

Well, i'm not saying it isn't possible. But the two aren't the same sensor; so, that could be one reason.

 

[Steve Kahn]

Well, i'm not saying it isn't possible. But the two aren't the same sensor; so, that could be one reason.

True, but every word we've had on the sensors (GH2 VS AF100) was that the AF100 sensor was the more "advanced" video sensor of the two, which would make perfect sense.

It is always said around here that of course the F3 has a better picture as it costs 3x the AF100. Accordingly it wouldn't make much sense for the GH2 to have better highlight handling capabilities than the 5x more expensive AF100.

 

[Barry_Green]

I'm disappointed to hear that this clipping issue is much the same as on the 200 and 500 cameras.

Well, of course it is -- it's an AG-series. They all have very similar performance in terms of colorimetry... they all have the same menus, the same gammas, the same choices. It's part and parcel of them all being largely color-matched and they all perform with a similar palette.

I guess I haven't complained about "chroma clipping" because - the AF100 is performing the same as every DVX, HVX, HPX170, HMC, and HPX500 out there. There's nothing new here, except that for the last eight years people have been loving Panasonic's colorimetry, but for some reason with the AF100 all of a sudden it's a "problem."

I guess if you've always disliked how the Panasonic "mojo" looks, you'll dislike the AF100 too. And if you've always loved how it looks, you'll love the AF100 too.

 

[Mac]

And if you've always loved how it looks, you'll love the AF100 too.

Everybody getting so sensitive here, it's like high school... I said that the "The only thing I've disliked about the picture from the HPX500 is the chroma/luma clipping disparity." I like the Panasonic look, and have mentioned it many times. The question that was asked in the review on this same page is, why can't the chroma/luma be dialed in so they clip togther? It's the weird colors in clipped highlights that draws the eye to the problem.

 

[Glenn Przyborski]

... why can't the chroma/luma be dialed in so they clip togther? It's the weird colors in clipped highlights that draws the eye to the problem.

Mac is correct, there's no reason why the chroma and luminescent signals can't roll into a soft, then hard clip at the same time. It's done on virtually every other camera including the GH1 & GH2. There is also no reason why the AF100 hard clips at 110 units instead of the usual 100 units. Panasonic has some of the best camera design people on the planet, possibly the soft and hard clip parameters are being defined in firmware. The camera's overall "look" and/or colorimetry is excellent.

 

[Shooter]

I do hope someone at Panasonic takes what you are saying into consideration Glenn. A well put argument and discussion about an issue that needs them to verify and work on.

Some companies truly listen to end users ( eg Adobe) and some dont. Hope fully Panasonic are not token "listeners".

 

[Danielvilliers]

Well, of course it is -- it's an AG-series. They all have very similar performance in terms of colorimetry... they all have the same menus, the same gammas, the same choices. It's part and parcel of them all being largely color-matched and they all perform with a similar palette.

I guess I haven't complained about "chroma clipping" because - the AF100 is performing the same as every DVX, HVX, HPX170, HMC, and HPX500 out there. There's nothing new here, except that for the last eight years people have been loving Panasonic's colorimetry, but for some reason with the AF100 all of a sudden it's a "problem."

I guess if you've always disliked how the Panasonic "mojo" looks, you'll dislike the AF100 too. And if you've always loved how it looks, you'll love the AF100 too.

That was what I was really afraid of when I started to see the footage from the Af-100, that Panasonic would come with the same (old) formula from its video side. This is what People buying into the large sensor camera market doesn't want... that video look. They want a look that is the closest possible to the organic cinema one and dynamic range being one of the most important to achieve it. They should have seen that the crowd they were after with this camera had evolved, more so with the dslr revolution and that they where used to a certain quality now. A look that there photo department has done with its $ 900 GH2 camera. Sure there will be many people coming from the eng world that will buy into this camera to complement their small sensor camera who will be very happy. But a big chunk won't be and it is still winter.

 

[Barry_Green]

That was what I was really afraid of when I started to see the footage from the Af-100, that Panasonic would come with the same (old) formula from its video side.

You were afraid of that? Most people were chomping at the bit for it. We asked for a large-sensor HPX170, and that's what they delivered. The Panasonics have been praised for the last 8 years for their color. Even when the XLH1 was sharper, and measurebators were crying about how "low res" the HVX200 was, if you put them side-by-side people usually preferred the look of the HVX footage. Because of the way Panasonic handles color.

If you don't like it, hey, that's okay, but lots of us are quite pleased with it because it delivers exactly what we were expecting and what we wanted.

They want a look that is the closest possible to the organic cinema one and dynamic range being one of the most important to achieve it.

And the AF100 delivers even more dynamic range than a 5D, so ... where's the complaint?

Sure there will be many people coming from the eng world that will buy into this camera to complement their small sensor camera who will be very happy. But a big chunk won't be and it is still winter.

Well, there is a saying -- you can't please everyone. Lots of people are in love with the low-res, aliasing footage that comes from certain cameras. I hate it. I think the AF100 delivers exactly the cinematic look that I was hoping for, and there are those who hate the "chroma clipping". You can't please everyone. And every engineering decision results in tradeoffs. Fortunately for the customer, there are many choices on the market. You just have to pick which set of features vs. compromises suits your own personal tastes best.

 

[Teodor Miljevic]

I agree with the critisizm in this topic. Almost everything i have seen from the af100 blown highlights look bad.
I don't know why you are fokusing on the color Barry (I mean we are discussing highlight handling) are you trying to tell us that if we want the nice colors we have to be content with ugly highlight handling? Someone else here has a valid point on why the gh2 doesen't have the same problem. I have a theory that panasonic maybe skimped on the DSP and put in a low bit one (maybe why the hdsdi only can produce 8-bit). Since the gh2 needs to produce 12 or 14bit Raw files(i don't know someone please educate me) it needs a higher bit pipe so the gh2 handles it more gracefully. It´s only a theory I hope I'm wrong since that means it won't be fixable in firmware.

Do people really think it's a valid approach to have to go to through post to get acceptable blown highlights(in high contrast situations)? That makes it practically worhtless in many corporate movie jobs where you need a finished picture and deliver fast. I mean the ex1 gives me acceptable highlight all the time and I don't need to have a special post pipeline to make it work. And when we are talking dynamic range i think in the case of the af100 people should really talk about black and white because if you start to factor in the hideous colorchanges and/or the need to severly underexpose and then fix in post the dynamic range is not that impressive.
I may come off as agressive and I appologize if someone feels that way but I think it's time to inform everyone that the emperor has no clothes. When it comes to highlight handling (my measurment is the percieved estetichal quality of the blown highlights) the 5d is leaps better, anyone with eyes can see it the only people that would argue this are people that like burned digital highlight (like the producer of battlestar galactica (and please don't put in the the other stuff moire, price sharpness because all of that is negatet even by their own product the gh2 (that I actually think has a nicer picture than the af100(so if they could mount the af100 lowpassfilter on the gh2 then you would get moire free picture with pana mojo and nice highlights there's an idea for you panasonic remove the stupid hdmi skipping frames and they would have a best seller at even 50-100% premium compared to the gh2

 

[Danielvilliers]

Should we be content of eight year old technology. I am just expressing my opinion here and I will vote with my wallet. It will be gh2 and then by middle of this year I will access the sony NXCAM. Buy the number of talk about this issue I do think that for many it is a subject of concern. If the Sony comes with its strongly rumored spec it will sway a lot of users toward it.

 

[dcloud]

I agree with the critisizm in this topic. Almost everything i have seen from the af100 blown highlights look bad.
I don't know why you are fokusing on the color Barry (I mean we are discussing highlight handling) are you trying to tell us that if we want the nice colors we have to be content with ugly highlight handling? Someone else here has a valid point on why the gh2 doesen't have the same problem. I have a theory that panasonic maybe skimped on the DSP and put in a low bit one (maybe why the hdsdi only can produce 8-bit). Since the gh2 needs to produce 12 or 14bit Raw files(i don't know someone please educate me) it needs a higher bit pipe so the gh2 handles it more gracefully. It´s only a theory I hope I'm wrong since that means it won't be fixable in firmware.

Do people really think it's a valid approach to have to go to through post to get acceptable blown highlights(in high contrast situations)? That makes it practically worhtless in many corporate movie jobs where you need a finished picture and deliver fast. I mean the ex1 gives me acceptable highlight all the time and I don't need to have a special post pipeline to make it work. And when we are talking dynamic range i think in the case of the af100 people should really talk about black and white because if you start to factor in the hideous colorchanges and/or the need to severly underexpose and then fix in post the dynamic range is not that impressive.
I may come off as agressive and I appologize if someone feels that way but I think it's time to inform everyone that the emperor has no clothes. When it comes to highlight handling (my measurment is the percieved estetichal quality of the blown highlights) the 5d is leaps better, anyone with eyes can see it the only people that would argue this are people that like burned digital highlight (like the producer of battlestar galactica (and please don't put in the the other stuff moire, price sharpness because all of that is negatet even by their own product the gh2 (that I actually think has a nicer picture than the af100(so if they could mount the af100 lowpassfilter on the gh2 then you would get moire free picture with pana mojo and nice highlights there's an idea for you panasonic remove the stupid hdmi skipping frames and they would have a best seller at even 50-100% premium compared to the gh2

af100 handles highlight fine with low knee. its the colors clipping on the highlights that is different from other cameras. is it tragically bad? of course not. its just a different way the panasonic cam reacts to color clipping..

@danielvilliers dude, we know you wont buy one. go buy yourself a gh2. stop all the FUD if you've never had the af100. others have said theyve returned it and they didnt like it and stopped there.

 

[Hywel]

I'm enjoying using my AF100, but I've only used it "in anger" on two productions so far. I'm hoping to home in one some better settings, because I am having a few issues getting the best out of it. As Art Adams noted, if you like having your skin tones up at 80-85% (which I do, because it makes pretty girls really seem to glow) you are constantly flirting with clipping. I believe this isn't chroma clipping per se, I think it is the red channel clipping right off the chip. No amount of processing later in the chain can bring back a clipped signal so it is already too late by the time the camera tries to tame things with the knee settings- the red channel has clipped, and the best it can do is take a guess at the colour. "Off the chip" RGB parade would be of much more benefit to me than the vectorscope, which simply doesn't give warning of this sort of clipping- it is the wrong co-ordinates to show it up. (The waveform monitor is fab, but RGB parades off the chip would be a lot more use to me than the vectorscope).

I'm also having banding/posterisation, which is a shame- probably it *IS* due to the signal being cleaner than my other cameras, which then shows the limitations of 8 bit processing/recording, especially if you want to start doing any sort of grading. I see why early testers recommended shooting for the look, because any sort of pulling shadows to one colour and mids to another immediately makes the banding more noticeable.

I didn't expect the AF100 to be a panacea. Of course not, for £4000. It has features and quirks in its footage (let's call them that, it isn't fair to call them issues or problems this early in my experience with camera settings). It'll take some getting used to- for example, I'm finding the footage quite contrasty, so I'm evening the lighting up on set. Is it an improvement over the HVX200? In some areas yes (shallow Dof...) in some areas no (holding up in the grade). Is it an improvement over the 5D2/7D? In some areas VERY MUCH yes (ergonomics!!! Moire! Aliasing! XLR!) in some other areas similar (the skin tone clipping issue is the same on the Canons, although maybe the AF100 out of the box settings tend to be sailing closer to the wind for making it appear). It is a little worse in some areas thus far (posterisation, in particular).

My impressions after a couple of shoots... I will not be using the 7D/5D2 combo again. The AF100 is SO much better in SO many areas which really matter to me (like being ready to roll when I'm set up, rather than overheating and turning off- to mention just one of dozens!)

I must admit to being a little surprised how much more robust the HVX200 footage seems, so I will keep shooting with those. I do want to be able to pull more out of the hat in the grading, as I'm used to being able to put off some style decisions until post from shooting RAW stills, so saving up for a second hand Red next year (and hiring one for a few days this year) seems like the way forward for me.

Hopefully I'll get better at tuning the AF100 to my needs in the meantime. It is a very solid product, well worth the money, MUCH MUCH better than a dSLR, but I am starting to think I might really appreciate the benefits of a much more expensive high bit high data rate solution. I may test drive a Nanoflash/Ki Pro Mini to see if adding bit rate to helps or whether it is really 8 bit, baked in gamma that's the sticking point.

Cheers, Hywel.

 

[Cosimo Bullo]

I'm enjoying using my AF100, but I've only used it "in anger" on two productions so far. I'm hoping to home in one some better settings, because I am having a few issues getting the best out of it. As Art Adams noted, if you like having your skin tones up at 80-85% (which I do, because it makes pretty girls really seem to glow) you are constantly flirting with clipping. I believe this isn't chroma clipping per se, I think it is the red channel clipping right off the chip. No amount of processing later in the chain can bring back a clipped signal so it is already too late by the time the camera tries to tame things with the knee settings- the red channel has clipped, and the best it can do is take a guess at the colour. "Off the chip" RGB parade would be of much more benefit to me than the vectorscope, which simply doesn't give warning of this sort of clipping- it is the wrong co-ordinates to show it up. (The waveform monitor is fab, but RGB parades off the chip would be a lot more use to me than the vectorscope).

I'm also having banding/posterisation, which is a shame- probably it *IS* due to the signal being cleaner than my other cameras, which then shows the limitations of 8 bit processing/recording, especially if you want to start doing any sort of grading. I see why early testers recommended shooting for the look, because any sort of pulling shadows to one colour and mids to another immediately makes the banding more noticeable.

I didn't expect the AF100 to be a panacea. Of course not, for £4000. It has features and quirks in its footage (let's call them that, it isn't fair to call them issues or problems this early in my experience with camera settings). It'll take some getting used to- for example, I'm finding the footage quite contrasty, so I'm evening the lighting up on set. Is it an improvement over the HVX200? In some areas yes (shallow Dof...) in some areas no (holding up in the grade). Is it an improvement over the 5D2/7D? In some areas VERY MUCH yes (ergonomics!!! Moire! Aliasing! XLR!) in some other areas similar (the skin tone clipping issue is the same on the Canons, although maybe the AF100 out of the box settings tend to be sailing closer to the wind for making it appear). It is a little worse in some areas thus far (posterisation, in particular).

My impressions after a couple of shoots... I will not be using the 7D/5D2 combo again. The AF100 is SO much better in SO many areas which really matter to me (like being ready to roll when I'm set up, rather than overheating and turning off- to mention just one of dozens!)

I must admit to being a little surprised how much more robust the HVX200 footage seems, so I will keep shooting with those. I do want to be able to pull more out of the hat in the grading, as I'm used to being able to put off some style decisions until post from shooting RAW stills, so saving up for a second hand Red next year (and hiring one for a few days this year) seems like the way forward for me.

Hopefully I'll get better at tuning the AF100 to my needs in the meantime. It is a very solid product, well worth the money, MUCH MUCH better than a dSLR, but I am starting to think I might really appreciate the benefits of a much more expensive high bit high data rate solution. I may test drive a Nanoflash/Ki Pro Mini to see if adding bit rate to helps or whether it is really 8 bit, baked in gamma that's the sticking point.

Cheers, Hywel.

Nice post Nywel. So maybe for now the hot ticket is mixing HVX and AF100 footage, using each camera where it's strongest. Barry's points make me believe they should cut well together.