Picture Profile Recipes

[Michael H. Stevens]

Originally Posted by Simon Wyndham

I had just typed a lengthy response, but lost it as I was trying to post! Arrrggghh!

Anyway, to cut a long story short.
1. Cines 1 and 2 are best for film out (which was their primary purpose) and heavy grading.
2. Cines do not stretch the blacks. They compress the overload the chips are capable of capturing into the recordable signal range.
3. Contrary to what Bill wrote, the cine gammas are your friend in harsh sunny conditions.
4. Cines capture more contrast than STD gammas, but at the expense of tonal range.
5. STD gammas can be made to behave like Cines if you adjust knee point and knee slope, but the camera needs to be able to output a SAW signal so you can see the gamma curve on a waveform monitor.

Simon: Interesting post. May I suggest you go for a quick run up those Malvern hills, get some good clean air, and then sit down and write us the long version.

I hope in the long version you may more fully explain what you mean by heavy grading and tonal range as opposed to contrast. Why do you say only CINE 1 and 2 are good for film out?

[Chris Hurd]

Originally Posted by Simon Wyndham

I had just typed a lengthy response, but lost it as I was trying to post! Arrrggghh!

When forming a long reply it's always best to write it up off-line (I use NotePad or WordPad) instead of the vBulletin interface, and then cut-and-paste into the Post Reply input field.

[Randy Strome]

Originally Posted by Simon Wyndham

4. Cines capture more contrast than STD gammas, but at the expense of tonal range.

This one does not match what I am seeing, but it is likely only the wording that has me. STD settings seem to be capturing more contrast, the question is, does the scene allow for that to fit the dynamic range of the camera. Cines seem to be variations of contrast squashing.

[Michael H. Stevens]

Originally Posted by Randy Strome

This one does not match what I am seeing, but it is likely only the wording that has me. STD settings seem to be capturing more contrast, the question is, does the scene allow for that to fit the dynamic range of the camera. Cines seem to be variations of contrast squashing.

Exactly. That is one reason I asked for more explaination.

[Simon Wyndham]

Ok, okay, it seems that we need a clarification of what is being talked about.

When I talk about contrast I am talking about the difference between light and dark. For example, in Standard gammas, if you have a bright sunny day, the shadows may look darker with crushed detail, while the highlights will be clipped. This will look more punchy, but detail will be lost. Hence some people may call this a high contrast look because darks are dark, and whites are very white. In actual fact it is a LOW contrast look because it is capturing limited detail in both the shadows and highlights. It can only capture decently either at the low to mid end, or the mid to high end, depending on your exposure.

The Cine gammas are high contrast because they can capture detail deep into the shadows AND detail into the highlights.

We need to remember that we are not discussing contrast in terms of how you might set your television set (ie a high contrast setting gives deep blacks and very white whites and therefore looks very punchy. I digress because contrast level on a TV set should really be called 'white level' :-) )

Cines seem to be variations of contrast squashing.

Technically in terms of how I am describing contrast you are correct. They are cramming maximum contrast range into the limited tonal range of the recorded signal.

Remember, that when you switch to, say Cine gamma 1 or 2, the darks may appear darker. But a lot more more highlight info is being crammed in there, so you can afford to bring the exposure up a bit to compensate.

[Simon Wyndham]

Wow, I just found my longer reply! I had the wrong window open. Doh!

I hope in the long version you may more fully explain what you mean by heavy grading and tonal range as opposed to contrast. Why do you say only CINE 1 and 2 are good for film out?

Okay. With Cine 1 and 2 you will end up with a very flat image because of the amount of contrast range it is cramming into the recordable signal. Unlike grading with a curves filter the camera cannot be selective, other than when it is using the DCC circuit which creates multiple knee points to control highlights (but with DCC the results are unpredictable, and often the DCC judges highlights not to be important when in fact they are. So sometimes DCC can actually be worse for highlight range. It depends on the amount of highlight area in the picture.)

In Standard Gamma the 'curve' is linear, ie straight (if we assume there is no knee). 100% input equals 100% output. The thing is though that the CCD is capable of capturing, in the 1/2" cameras, a 400% more signal over and above the maximum recordable output highlight level. So, you have to compress the highlights in order to cram that extra signal into the recordable picture. The result of that is that you are recording a higher range of shades within the same recordable signal area, and so graduations might be coarser, even though you are seeing more actual highlight range. Hence limited tonal range.

If you push things too far in post to try and put more punch into the picture, you may end up seeing the limitations. A 10-bit recording format would be much better at handing such curves.

[Piotr Wozniacki]

I'd add to Simon's definition of contrast, that what most people consider "contrasty" is greater range between blacks and highs, while Simon's high contrast is about the resolution of midtones in between. Hence: cine gammas are more contrasty, and standard gammas - more punchy.

This is consistent with how the various gammas are (briefly) described in the EX1 manual; counter-intuitive at the first sight.

[Simon Wyndham]

I'll also add that what i know about the technicalities of all of this is what I have gained by picking engineers minds. If they were members of these forums they'd be able to describe what I am trying to put into words with far more accuracy. But the caveat would be that we'd all be suffering from a far worse headache! ;-)

Alister, feel free to chime in here!

[Randy Strome]

Originally Posted by Simon Wyndham

Technically in terms of how I am describing contrast you are correct. They are cramming maximum contrast range into the limited tonal range of the recorded signal.

I think of contrast as a luminance ratio based on the brightest white to the darkest dark. In that context, using an example where an STD setting is just filling the histogram from right to left, the Cine settings (if the histogram is recentered using camera settings) will each in their own degree pull the histogram from the right and left, leaving a lower contrast end product.

Conversely, if one of the Cines is used and it fills the histogram from right to left, the recordable contrast ratio is already maxed out, and switching to STD can not increase it (but will blow the ends off, or at least one, depending on settings).

Side note: I am finding the EX-1 files to be nicely "curve-able" without noticable tonal degradation (so long as a reasonably bright exposure was achieved initally).

[Simon Wyndham]

Originally Posted by Randy Strome

the Cine settings (if the histogram is recentered using camera settings) will each in their own degree pull the histogram from the right and left, leaving a lower contast end product.

Hence we are talking about two separate things. Ignore your definition of contrast. The contrast I am talking about is the contrast range or luminance range that is *captured* from the CCD's and then compressed into the final signal and *not* the final effect of a histogram or 'look' of the picture in terms of punchiness. It is a hard thing to visualize, but imagine this;

You have an empty glass jar of 100mm height, and you have to fit a 140mm high piece of flexible wire into it. The top of the wire represents the highest white possible that the CCD's can capture, while the low point of the wire represents the blackest black. The top of the jar is the maximum recordable white level. How do you fit the wire into the jar?

The Cinegammas, particularly 1 and 2 will output a maximum ire below 100. But this is not the same as maximizing the contrast level on a TV set, or in post using the Levels adjustment.

Side note: I am finding the EX-1 files to be nicely "curve-able" without noticable tonal degradation (so long as a reasonably bright exposure was achieved initally).

The tonal limitation is one of technicality, and is not one of exposure. If you cram a curved higher range into the same range as a linear standard range you will have to make a compromise somewhere.

[Michael H. Stevens]

You can see this std vs cine demonstrated by setting up a shot with std1 and then without touching anything switch to Cine1 and you will see just how much you can crank exposure to get a lot more at the top.

[Randy Strome]

[QUOTE=Simon Wyndham;836308]Hence we are talking about two separate things. Ignore your definition of contrast. The contrast I am talking about is the contrast range or luminance range that is *captured* from the CCD's and then compressed into the final signal and *not* the final effect of a histogram or 'look' of the picture in terms of punchiness.QUOTE]

Hi Simon,

As I understand it, the "pre-compression" contrast range that is read by the CCD's would be the same in both instances and as you said, would be based on the technical capabilities of the system. The curve (or lack thereof) that is applied forms the captured image.

In terms of a user choosing a Gamma setting based on contrast alone, the pre-compression contrast is of little use, as there is no going back. The wire analogy defines value remapping and also can not be undone.

If you meant to say that the Cines take the existing contrast level at the sensor and compress (or remap) them into a lower contrast range then we are saying the same thing.

[Sebastien Thomas]

Originally Posted by Simon Wyndham

Hence we are talking about two separate things. Ignore your definition of contrast. The contrast I am talking about is the contrast range or luminance range that is *captured* from the CCD's and then compressed into the final signal and *not* the final effect of a histogram or 'look' of the picture in terms of punchiness. It is a hard thing to visualize, but imagine this;

You have an empty glass jar of 100mm height, and you have to fit a 140mm high piece of flexible wire into it. The top of the wire represents the highest white possible that the CCD's can capture, while the low point of the wire represents the blackest black. The top of the jar is the maximum recordable white level. How do you fit the wire into the jar?

The Cinegammas, particularly 1 and 2 will output a maximum ire below 100. But this is not the same as maximizing the contrast level on a TV set, or in post using the Levels adjustment.



The tonal limitation is one of technicality, and is not one of exposure. If you cram a curved higher range into the same range as a linear standard range you will have to make a compromise somewhere.

I just wrote a page with the curves out from the EX1. This should illustrate your words. Maybe you can add some comment on it, as I won't have time right now.
I will try to add more grabs this week, changing gamma, knee (for std gamma curves), etc.

Check this here : http://www.lecentre.net/blog/pmw-ex1/gamma

[Simon Wyndham]

Good one Sebastien. You saved me the trouble as I was going to write a similar article.

With the adjustments available on the EX1 and the F300 series, I am surprised that a SAW signal isn't in the standard menus as it is essential for setting up your own gamma curve settings.

[Randy Strome]

Very interesting guys, and thanks for the post.

I have to play village idiot again and admit to not understanding the fundamentals here. If I have it correctly, these are representations of what is happening to a linear 0-255 gradient when each of the gamma setings is applied. Is that correct?

If so, in (for example Cine 1) why is every value from 207-255 being mapped to a flat 207?

I thought I understood your wire analogy, but did not imagine the wire being bent flat at both ends. I thought we were talking about a smooth rolloff as is depicted by the curves in the user manual, but certainly not a long flat spot from 207 on. Well...I can not understand what value there would be to that, but then again, I have always found pre-processing curves to be a mental puzzle.

As you can see, I need to be set straight. HHHEEELLLPPPP!