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James Malamatinas
Questions about Grading/Broadcast/Studio monitors
on Jun 9, 2012 at 8:34:38 pm

Hi, I looked for a specific forum for this but cannot find anything so please move if it is inappropriate.

I'm trying to learn about different types of monitors used in movie production and in particular monitors used for the most profressional level of grading. I've found it very hard to find useful information in any single place however have pieced bits together but still have a few questions. I've learned a fair bit form this link.

1. Does anyone have a link to useful information on the differance between Grade 1 and Grade 2 monitors? I have a list of various factors including colour temp, greyscale range, off-axis viewing etc but would like to read about it in more detail.

2. It seems that consistent colour temperature is essential for high quality monitors, I understand the general meaning of colour temperature but not exactly how it applies to monitors (is it the colour temperaure of the light being emitted), or what it means to be consistent?

3. The link above suggests that the best broadcast monitors necessitate a perfect gamma curve but I have seen else where that some monitors utilise a s-curve (Sony, I think do this). What is the differeance and which is better?

4. Each monitor is capable of covering a certain colour space and from my reading Rec.709 appears to be the most commmon. However I cannot find much information on whether extended colour spaces such as the P3 digital cinema colour space above are practically used in a film workflow. What sort of colour spaces are used in professional film production and are do people have links for further background read?

5. I have heard that Dolby showed a monitor with extended brightness at NAb this year, where the normal recommended brightness is 80-110 nits, this worked at close to 600. Does anyone have further information how this works, from my reading it appeared that consumer TV and LCD that have a brightness of much higher than 110 are generally considered poor (although that is obviously due to multiple factors, not simply brightness.)

These are only a small number of questions but I don't want to overload - thanks very much for any input. Unless I'm missing something and not using Google very well I'm quite suprised how little information there is on broadcast monitors, how they work and what makes them better than cheaper reference monitors.

James


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Joseph Owens
Re: Questions about Grading/Broadcast/Studio monitors
on Jun 11, 2012 at 6:11:20 pm

[James Malamatinas] "but not exactly how it applies to monitors (is it the colour temperaure of the light being emitted), or what it means to be consistent? "

Try this: http://en.wikipedia.org/wiki/Color_temperature

The consistency that Peter appears to be talking about (as applied to grey scale) is the uniformity of correlated color temperature at varying intensity (emitted brightness level), whether the spectral content veers away from a color temperature of "white" constent with the "cool/blue" character of D65 across the grey scale. In other words, you sort of have to wrap your head around the idea that "white" is not just a pure mix of R/G/B, but what your brain is interpreting to be "neutral" and untinted inside the calibrated emissivity standard. Think about what "white" is under tungsten, and again what it is under D65 and fluorescent, for that matter. They are very different. Think what happens to shades when the illuminant is not flat-spectrum.

[James Malamatinas] "suggests that the best broadcast monitors necessitate a perfect gamma curve but I have seen else where that some monitors utilise a s-curve"

Contrast over the grey scale needs to be compensated for varying viewing conditions. Gamma itself is mathematically a power transfer function (the gamma number is an exponent). An S-curve is a non-linear ease-in/ease-out transfer that affects gamma for local viewing conditions and is not strictly speaking part of the 601 recommendation. In this case, its would be more like a compensation for deficient emissivity at the extremes of a brightness range. Gamma transfer of 2.2-2.4 is recommended for a specified brightness (the ones cited in the presentation) under a specific viewing condition, to yield a predictable volts/brightness characteristic that is consistent with emission technology displays. ie not print.

[James Malamatinas] "However I cannot find much information on whether extended colour spaces such as the P3 digital cinema colour space above are practically used in a film workflow. What sort of colour spaces are used in professional film production"

The Digital Cinema Initiative uses the X'Y'Z' coordinate system for wider-gamut performance to emulate carbon-arc film-transmission presentations, so that theater audiences feel they are still getting a movie for their price of admission. This is actually the original reason for instituting the use of "LUTs"-- to simulate the predicted outcome of generating production values in one medium that is destined for presentation in another. You should be able to find plenty of reading under DCI searches.

I thought the discussion about how turning a monitor up to "11" (for the suckers at home) was fair. The practice is rampart in consumer appliances. Do you really need a 600 horsepower family sedan? How about a vacuum cleaner that can support 10 feet of water in a standing column? Its a sales pitch.

jPo

You mean "Old Ben"? Ben Kenobi?


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James Malamatinas
Re: Questions about Grading/Broadcast/Studio monitors
on Jun 14, 2012 at 9:25:39 pm

Hi Joseph, thanks so much for your reply. Whilst it completely clear you know what you're talking about I have to admit to being a little overwhelmed!

I'm literally just starting out with trying to learn colour theory and how it ties in with digital systems, grading, monitors and camera and have in the last few days been tackling terms such colourtemperature, model and space, grey scale, gamma, hue, chromaticity, chroma, saturation, value and luminance all simultanesouly - needless to say it's a lot to learn!

I keep going back to your answers and trying to fully comprehend it all but I'm struggling a little. Is there anyway you could try and explain each point a little more simply? For example;


[Consistent Colour Temperature] The way I'm understanding your point is that it refers to well a monitor would maintain the specific colour temperature of pixels as the brightness of the monitor is increased or decreased. Is this correct? What is D65, is it this? If so I'm finding that page difficult to interpret!

[Gamma Curve] As I understand it gamma is the encoding/decoding of light into a range which human vision can detect i.e. preventing an image from being too bright or dark. Are you saying that the S-log helps prevent inefficiencies by ensuring that bits aren't sent to too extreme highlights or shadows? Have I got this completely wrong? I'm finding some of the maths terms (logarithmic, power-law, etc) difficult to get my head around.

As for the DCI I'am about to start reading up on that now, thanks again for your advice!


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