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Legend
July 16, 2018
Question

basics of color correction (tv part)

  • July 16, 2018
  • 5 replies
  • 4599 views

I found this really good and concise explanation of color basics re: basics.  It was some guy in Los Angeles, who won't mind me sharing this.

I just copied pasted stuff to notepad and won't edit the thing ...you'll get the idea the way it is...It's pretty cool way of just explaining and might help eliminate some confusion, like my own, for example.

=========begin paste=====

The Mini Monitor isn't just a TB to HDMI adapter, like the adapters your can buy for $7 off Amazon.

It converts a computer data signal to a TV signal. Fundamentally different types of signals. This is why you can't just plug a TV directly into your HDMI port in your computer. It would show up as second computer monitor, extending your desktop, displaying a computer signal.

TV video signals can be progressive, interlaced, different frame rates, and adhere to standard formats like ATSC, PAL, etc., encoded in Y'CbCr. Computer video signals are different beasts entirely, and computer monitors that are color-accurate and 10-bit for graphics work still are not equipped to handle interlaced signals or the various frame rates you find in TV signals.

The Mini Monitor's purpose is to allow you to view a true TV signal.

Thus BMD would never need to build in a second-screen full screen video playback like Premiere or FCP into Resolve, at least for color correction, because that could never be a true TV signal. It might, however, be useful in Resolve's growing capacity as an NLE apart from color correction, to be used purely as a non-accurate preview for editorial purposes (which is what Premiere and FCP and other NLEs are doing).

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The issue here is the type of signal. As the broadcast online editor and/or colorist, you are responsible for shaping and delivering the actual deliverable end product: an electrical signal. Not a picture, not an image, not a video. These are higher-order constructs that exist in our minds. The actual thing that we are delivering, wether by file or by tape, is a representation of an electrical signal. A very particular type of signal. You need to monitor the kind of signal you are going to deliver. So you have to monitor your images as a TV signal.

A computer display with an application window full-screened is a computer signal with information about all sorts of stuff. It is not a TV signal.

You need to be able to "see" your signal. This means to view the pictures encoded by that signal, and at the same time measure various other properties of that signal via a set of external scopes. You do this to ensure that your signal is in technical compliance with laws that govern TV signals in your region, and to help make color correction decisions.

You use a Mini Monitor to get a TV signal out of your grading app, then monitor that signal on a calibrated TV and a set of external scopes. Your signal is managed by the Mini Monitor, containing only your TV signal.

Plugging your monitor into the computer, you are seeing a signal generated by the graphics card containing other information managed by the OS. We don't want to "see" or monitor that. That's not what we are delivering.

Think of it this way: the Mini Monitor turns yours computer into a "TV station" of sorts. You use your calibrated TV to "watch" the TV signal "broadcast" by your computer-turned-TV station.

Same metaphor extends to grading movies. In this case, your UltraStudio or other monitoring device feeds a projector. Your computer then becomes a movie theater projector, and you watch it in a grading theater on a silver screen.

It's all about the signal.

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    5 replies

    Legend
    August 2, 2018

    ahhh, thank you so much !

    Legend
    August 3, 2018

    Wow, what a cool gadget ! Did the rec 709 emulation with calibrator and now what I see is what I imagined the shot (clip) would look like when I shot it , and the tonal range and stuff is good. So I didn't waste my money doing this stuff. The field monitor ( off BM SDI) is also now much closer to primary display (Eizo). Brightness control fixed much of the 'contrast' issue cause squeezing full HD into 10" sorta makes things a little darker, sorta. Pixel to Pixel setting gives better info but the stupid field monitor is just for location or off camera stuff anyway.  It's useless on my editing computer.

    Thanks for all your help, you guys. Really appreciated !

    Legend
    August 3, 2018

    I got lazy and instead of shooting color (kodak) swatches/tonal scale, with 32k light on it, I stuck color bars and tone into the sequence I had and just made a BD iso from encore and burned that to disc. Played in computer ( looks great) and on TV ( looks almost great.. black across bottom is closed ). Colors OK. Very nice all in all.

    Thanks for all the help and info !  Maybe someone down the road will get some benefit too from your contributions !

    : )

    Legend
    July 25, 2018

    Is kinda complicated, my intent. On a personal level I simply want to finally (after many years) have a way to get very close (if not exactly match) to SEEING on my monitor(s) what is presumed to be the STANDARD (SMPTE) color and luminance, etc. for TV.

    My belief is that as I adjust levels and color of my own shooting on those new color calibrated monitors and export the product, it will be very close to color etc. of TV standard.  In order to do this I figured I could use some advice and help and suggestions.

    Fortunately people have ( like yourself ) been very helpful. Your mentioning the Eizo monitor you use prompted me to look into that monitor and it is arriving today.  I may have questions about setting that up properly later on.

    ON a more universal level this thread might serve to help others who want to do something similar with their workflow in terms of getting the best representation of color for a reasonable price so that if they export things they can be assured they are exactly or very close to the TV SMPTE standard.

    I haven't gotten into the nitty gritty of the actual IRE scale used in the past for CRT monitors and whether the new progressive TV signals have changed that 'range'.  I'll have to research that or maybe someone will chime in about what they know.

    That's the purpose.

    Yes, I know about the internet and need to sift through the stuff. It just seems to be worse than ever right now.

    Legend
    July 25, 2018

    When I think about 'nits' instead of IRE ( with log stuff today) I realize of course that this subject of color and standards may be a little too ambiguous and confusing with regard to a hobby. If there is some problem with this subject in the lounge, I am more than happy to have the entire thread deleted by those people who are able to manipulate the threads.

    I've got what I need to start getting better at dealing with color and levels and scopes, etc., without regard to particular programs ( PPro, AE, Resolve, etc. ) for my own output and understanding. I know people who are currently shooting commercial stuff using all of the above and I can get info from the DIT people or DP to get what I need for info.

    So, D Fosse, if you hate this thread, just delete it. Or whatever.

    Legend
    July 21, 2018

    Thank you D Fosse. Yes, this thing has built in stuff, so I'll use that. Wasn't sure if it's good enough to rely on without external gadget. I shoot with a Nikon d800 dslr, using an atomos to record video via hdmi ( DNxHD). So I can probably use the default sRGB (web) and Adobe RGB (print), but if you do video, would you go with the default rec 709 or adjust it slightly ?

    It's DNxHD 220X,  10 bit 4.2.2, 1920x1080, YUV, very basic stuff.

    : )

    Legend
    July 24, 2018

    YIKES ! This stuff gets complicated fast !  I got my little ref monitor working well with SDI out from BM playback card, and then all my sound stuff went nuts for the computer when just trying to play mp3's and using headphones on computer case.  OMG !

    Sound was getting routed to the ref monitor but when trying to use normal sound stuff on computer is was all messed up.

    Whoever it was on the internet that gave me advice about settings in PPro about audio preferences and playback stuff should be whipped with a wet noodle !

    D Fosse
    Community Expert
    Community Expert
    July 25, 2018

    I must admit I still have no idea what it is you're trying to accomplish here - especially not in the context of the thread title. Hopefully we get a "why" as this unfolds, in addition to the "how".

    Whoever it was on the internet that gave me advice about settings

    An old hand such as yourself obviously know that nothing you read on the internet can be taken at face value. Including this. In journalism it's called "source criticism", although it seems to have fallen on hard times lately...

    Legend
    July 16, 2018

    yes, thank you ! As a place to bring really smart people together to explain things to newcomers ( whatever their sources and products go to ) this is a really cool place ! Thank you so much !

    As it happens I also ordered a 'field monitor' or 'reference monitor' to go along with the mini monitor card. That is calibrated I hope, and has some build in LUT's ( rec 709 etc. ) which hopefully will do some cool stuff when I use HDMI out from my graphics card ( using CS6 for example ) just to get a look at the TV signal. I have no clue if that will work yet until I install the card, drivers and see how CS6 interacts. Worse come to worse, I can put a clip into resolve, that I'm using in Ppro, ( just the color part of resolve) and see what I see re: Y, Cb, Cr. )  I have no clue what will happen cause I haven't installed it yet.

    You are being so helpful and explaining things so well that I feel people who visit the lounge re: this subject will benefit tremendously from your expertise and experience with PPro and delivery !

    Thank YOU !

    davescm
    Community Expert
    Community Expert
    July 17, 2018

    rodneyb56060189  wrote

    As it happens I also ordered a 'field monitor' or 'reference monitor' to go along with the mini monitor card. That is calibrated I hope.............

    A monitor may have been calibrated at the factory but that does not take away the need for regular calibration going forward. If you are serious about colour, invest in the hardware and software to calibrate the monitor. For video that means test signals and a hardware device to measure the screen output - you cannot calibrate by eye.

    For computer imagery - a calibration & profiling software package along with a hardware measurement device (e.g. i1Display).

    Dave

    Legend
    July 19, 2018

    DOG DELIVERS TO DOG

    The nice Fed Ex dog is on it's way to deliver BM card and reference monitor.

    The apt. building I live in has a complicated 'buzzer' system and sometimes drivers don't know how to use it to contact tenants to get in building, and announce their arrival. Consequently, just like a dog waiting for it's owner to come home from work, I have my nose pressed to the glass window looking for the Fed Ex truck to pull into the parking lot.

    I hope I can get this stuff to work with CS6. Investigations on internet have lead to nothing but confusion, contrary information, and a general sense that nobody in the world ( including manufacturers and software developers ) have a clue what is going on !

    D Fosse
    Community Expert
    Community Expert
    July 16, 2018

    It may be a "true TV signal", but how can he talk about color correction without any color correction? Or does he really believe that a mini monitor displays "correctly" out of the box, or even that two mini monitors will display identically? Of course they don't, and of course they won't.

    Legend
    July 16, 2018

    Thanks for your input. Are you saying this is philosophically unsound ? Or that a breakout box and capture/play cards, maybe with a loop, with an oscilloscope to test voltage ( IRE scale ) is necessary to fine tune it ??

    ??