Krontalk

Chronos => Chronos User Discussion => Topic started by: Nikon1 on September 10, 2020, 02:10:45 PM

Title: How does the Color Matrix work?
Post by: Nikon1 on September 10, 2020, 02:10:45 PM
Has anyone some Experience with the Color matrix inside the Chronos White Balance menu?
 I kind of found out how it works, that it basically is a RGB to RGB Remapping Lookuptable for the Sensor data. The only thing i can find about it is some Asian App, which aparently uses the Same concept, but actually has Sliders to mess around with Contrast, Saturation and Exposure, which the Chronos lacks, and setting this Look-Up-Table/ Color Matrix by trial and error is not just frustrating and very time Consuming, but almost impossible to do propperly without messing something about your colors up from what i done with them untill now.
 So my question is, has anyone done something with the Matrix yet and any tips/ tricks, or is there Any further documentaition on the Topic?
 Also, is it planed to add an slider /value Box for Contrast/ Saturation/ Exposure? Shouldnt be that hard to add, but would make this Color matrix actually useable.
 and, is there any way to save multiple Color Profiles/ Name them? also havnt figured that one out yet. Allways resetting the one over and over by hand seems kind of annoying....
Title: Re: How does the Color Matrix work?
Post by: Nikon1 on September 11, 2020, 11:33:26 AM
So i found this, and thats about it for color Matrix stuff.
 Adding Sliders to More easily adjust Brightness, Saturation and Contrast would allready help a ton. If you can find a Way to add more easy control over the Colors, even better.
Title: Re: How does the Color Matrix work?
Post by: lwaters on July 15, 2021, 11:01:42 AM
I would also love to know more information on the Custom Color Matrix...I am really struggling to get a pure white balance and would love to be able to understand anything about it.
Title: Re: How does the Color Matrix work?
Post by: Nikon1 on July 15, 2021, 11:24:14 AM
Do you use the Internal Monitor or an External one?
 Just from my personal experience the internal Monitor is mostly "good enough" to set your frame up and pull focus when using Digital Zoom Feature.
 But i found that i did really struggle with proper Exposure until i was able to have a Histogram on my External Monitor at all times.
 Exposure is just somewhat hard to judge on the Built-In Screen if you are going for the Best footage the Camera can Capture, also Color looks off on the Internal Screen. Not by a ton, but just enough that someone who doesn't know a lot about color would even notice. And i absolutely trust my SmallHD 502 Bright over the Built-in Screen regards Colors and such.
 .
 So if you rely on the Internal Screen only For White Balance or color settings you maybe have a hard time, indeed.  Now i also Usually only shoot in Daylight /with Daylight LEDs with good color or Tungsten Lamps, and for that the Presets usually work fine for me. Have to say, that i also try to Save as DNG if Quality of the Footage is of concern, so even if i don't hit it perfectly or just dislike how it looks, i can just go and adjust it in post.
 .
 If you save in H.264 However, you have to be a bit more careful, if i have to do that, i would usually use the Custom Color Matrix and set it to:
 .
 1    0     0
 0    1     0
 0    0     1
 .
 This will give you a very Flat, desaturated color profile and usually allow for a wider range of options in Grading the Footage Later. Make sure to get the White Balance right however, as you cant really change that easily later if you are way off when working in H.264.  .
 
 
Title: Re: How does the Color Matrix work?
Post by: lwaters on August 09, 2021, 03:02:16 PM
You're absolutely right, I find myself underexposing often. Even when I am pushing to where I am seeing zebra lines and backing off slightly, it still doesn't seem right. I don't have an external monitor for it (yet). When you're adjusting exposure with your monitor, what are you basing your correct exposure off of? Or how are you obtaining proper exposure?

I'm still on this color correcting adventure and have been attempting to calibrate using an xrite passport II but can't seem to get it to where our numbers match up to their given color checker hue values (even after running it through the xrite color calibration software). I just want to make sure we are balancing correctly, it is of the essence for this project we're working on.

Xrite's customer service has been dismal. Would you happen to have any advice?
Title: Re: How does the Color Matrix work?
Post by: Nikon1 on August 10, 2021, 06:36:20 AM
I am extremely busy right now, so i cant really answer in detail, but will try to reply in 1 or 2 Weeks and give a little info about i work with Histograms.
 If urgent, try to look up any Photoshop Tutorial about Histograms (Levels) or any other Image Editing Software, also Tutorials on exposure in general.
 I am pretty sure, there is plenty good material about that online already to look at to learn about it in general.
 .
 For the meantime just a question for you, have you been able to produce whatever color profile/look /color result you are looking go get with any other camera so far, if yes, can you post any sample image from that /with that look/ Settings applied?
Title: Re: How does the Color Matrix work?
Post by: mklinger on August 10, 2021, 07:49:27 AM
You're absolutely right, I find myself underexposing often. Even when I am pushing to where I am seeing zebra lines and backing off slightly, it still doesn't seem right. I don't have an external monitor for it (yet). When you're adjusting exposure with your monitor, what are you basing your correct exposure off of? Or how are you obtaining proper exposure?

I'm still on this color correcting adventure and have been attempting to calibrate using an xrite passport II but can't seem to get it to where our numbers match up to their given color checker hue values (even after running it through the xrite color calibration software). I just want to make sure we are balancing correctly, it is of the essence for this project we're working on.

Xrite's customer service has been dismal. Would you happen to have any advice?

Hi! If you want to learn about post-production color correction, I highly recommend checking out Gerald Undone's video on the topic.

https://youtu.be/71ebKrT2XlY

If you have a proper color calibration target like the xrite you are talking about, you definitely want to learn how to use the Vectorscope in a tool like DaVinci Resolve.  Gerald's video linked above is a really good place to start for that.

Once you have created a proper color correction for a given lighting condition, you can create a custom LUT for your Chronos and apply it in similar situations for a very good starting point.

FWIW, proper exposure on the Chronos 2.1 is a bit tricky as it seems to change sensitivity based on things that shouldn't change the sensitivity (like changing resolution).  They are working on fixing this issue in the firmware, but for now, be aware that this happens and that it doesn't behave as nicely as a DLSR or conventional video camera.  If you are in a controlled studio environment shooting critical work, I would recommend taking test shots and bringing them into post on a computer to properly check for exposure.  If that's not possible, yeah, try using the tools on the camera as best as possible, but that's not ideal.
Title: Re: How does the Color Matrix work?
Post by: Nikon1 on August 20, 2021, 03:00:50 PM
You're absolutely right, I find myself underexposing often. Even when I am pushing to where I am seeing zebra lines and backing off slightly, it still doesn't seem right. I don't have an external monitor for it (yet). When you're adjusting exposure with your monitor, what are you basing your correct exposure off of? Or how are you obtaining proper exposure?

I'm still on this color correcting adventure and have been attempting to calibrate using an xrite passport II but can't seem to get it to where our numbers match up to their given color checker hue values (even after running it through the xrite color calibration software). I just want to make sure we are balancing correctly, it is of the essence for this project we're working on.

Xrite's customer service has been dismal. Would you happen to have any advice?
Still dont have time to write an full Reply/ Explanation about Exposure/Color rn, but can give a little update.
 I got myself one of those Color Checker Passport Photo II (after ordering i noticed, that they also have a Passport Video one, i just assumed it is the Photo one you have, you didnt mention it, which one it was), just to see what you are dealing with here and also to improve my own color Workflow. So far i usually got away with a lot of guesswork and doing whatever i felt looked right, and was lucky to have worked with Cameras that apparently where close enough in terms of color so far, that this never was a Problem. With the Chronos 2.1 however, i think i really need to learn proper Color Work/ Management to improve my Results further (see my last post on the 2.1 Footage Thread for example).
 .
 @mklinger:
 Thanks for posting that Link, didnt watch the full thing, but helped me understand color work in Resolve a bit better. While this is for sure a great video in general, i dont think this fully covers what Iwaters wants to know. Most of those kinds of Tutorials are (sadly) very focused on Skintones and things like that, which i get why they would be Important for Cinematic Purposes and i also know how hard it can be to get them Right. So its fair to talk about them. But from what i understand from Iwaters, is that its more about getting the Overall Color as Close as Possible to "Real World" color.  .
 @Iwaters:
 regards X-Rite customer Service, well, i went to read up and Look around their website a bunch, and it seems like they Offer Training&Seminars, which they charge you money for.
 https://www.xrite.com/learning-color-education/training
 So alone from that Fact, and the Fact that they list most of the Color-Checker Products on their Website as "Experience Level  -  Advanced" under the Tab Specifications:
 https://www.xrite.com/categories/calibration-profiling/colorchecker-passport-video
 I assume that the are not all that much about spending hours explaining you "basic" Stuff (depending on what you asked them, but i guess they consider that very basic knowledge) via Phone/ Mail or something like that for free. I think they would probably help you out, if you came at them with some very specific Advanced Questions (Transformations of/to obscure Colorspaces, software compatibility, ect.), but they will most likely not spend the time to explain the basic things to every olīdude with a camera that is trying to figure out why his colors look kinda strange.
 .
 Regards color in general, i have to say, it is VERY Complex and quite hard to understand, but i am Trying to break it down as much as possible here. I am no where near even understanding a Fraction of color science that there is, nor am i any kind of expert in this field. I feel like no where near competent enough to explain this, but i am gonna try anyways to the Extent i understand it.
 .
 First off, you need to understand, that there is "Real World Color", meaning the actual Properties of Surfaces/objects that respond to light in a certain way, letting you see whatever color they then seem to be. Then there is Light, which influences whatever those Colors Look like by a lot. Then there is also the Viewer or Camera observing the whole situation. As an Extreme Example take Color-Blind People, who cant see certain Colors. Its Like that, but not quite as bad with digital cameras. Digital Cameras can currently not capture every color (/Saturation Value) there is, also Dynamic Range is Limited to less than there is present quite often in Every day Situations. That means, whatever Color is Captured by the Camera is already not matching the Full Spectral Range that is Present in Reality anyways (for the Moment Ignoring Lighting). Then there is Color Spaces Also, meaning you now also need to Consider that even if you were to correctly map your Image To real World Colors Perfectly somehow, you would still run out of color Space in most Situations eventually (depending on Color Space ofc, but talking about sRGB f.Example). So you will have to make Compromises eventually to display the best Result for whatever the Usecase might be (for Cinema usually Aesthetics, so its usually not always technically correct Color).
 All in all a quit Complex topic, and those Trainings X-Rite offers are actually quite justified, because there is just a lot to it, to be explained, if you really want to get into it and understand it well.
 .
 For the Absolute Basics, i highly recommend you to check out these two Papers by x-Rite, and Study them Closely, as i assume that this is quite a bit of the info they would throw at you in those Trainings in the first Hour or two anyways.
 I dont know about your general Level of Knowledge about Color (maybe you even know more than me by now or something), but i can just say, these Infos are what its about, if you want to understand whats going on. Cant explain any of that stuff even half as good as they do there:  https://www.xritephoto.com/documents/literature/en/L11-176_Guide_to_CM_en.pdf
 https://xritephoto.com/documents/literature/en/L11-029_color_guide_EN.pdf
 .
 .
 About your Color Values not lining up perfectly with the theoretical Color Checker Values:
 https://xritephoto.com/documents/literature/en/ColorData-1p_EN.pdf
 Well, for one try playing around with White Balance, that should already change them quite a bit, and also Tint (green-Magenta adjustment of White Balance).
 Otherwise, even if Whitebalance is as Close as you are gonna get it, it will probably still be off at least by a little bit most of the time, because if you just hard Mapped it to the Chart sometimes it would look strange, so it goes a little easy on it to make it look somewhat natural. But the WB-Adjustment should already get you close, use the Methods shown in the Video mklinger Linked to fine adjust your image if you want to get it to actually mach the Colors (can go into some more detail later, if you want on how to do that).
 Other thing i came across, while trying to figure out my own Color Workflow, was this Video:
 https://www.youtube.com/watch?v=xHGicvsdwWI
 Now, i have actually not watched this video, just clicked through it while muted, to figure out, you need to actually find some hidden button in Resolve to set a mask for those Color Charts.
 I literally just Searched for "resolve 17 color match x-rite" on YT, and this was the First thing that came up, after spending way too much time almost loosing my mind trying to figure out why my colors would go absolutely crazy when just pressing "match", and about to give up with Resolve at that point (like seriously, why is that hidden like that? I was seriously in Doubt if Resolve can actually even color Match those Charts, or considering if i was just dumb or something, even spent quite a bunch of time trying the Same thing with a bunch of file Formats and eventually a bunch of different Cameras, just in case. Would have taken ages to figure that one out on my own, and would have probably given up trying before finding out how to do that...).
 But this Video also seems to go into detail on how to expose correctly with Color Charts like that one (there seems to be a ton of Videos just like this coming up as recommended when you watch that, so feel free to watch a bunch, maybe one of them will help), so you could watch that/ those until i am able to try my best explaining what i know about this/ Specific to the Chronos.
 .
 I think we talked about this very Problem with Color Matching a Real Life Situation via Mail before, but dont quite remember, where we ended that Conversation, been a while.  I also dont quite remember your requirements anymore, but it seemed of Technical Nature, not Cinematic (i think to remember that you never went into too much detail about your usecase or specific Requirements, so if confidential, just try to describe the Desired Result in terms of Color/Saturation/ect. as close as possible without going into too much detail about your Project.).
 Was about maxing out Saturation on colors or something like that back then, if i remember Correctly...?
 .
 As i already said, i dont know your current Level of knowledge or your usecase or field of work, but if you want to go deep into color Science, check this link out (from what i know, this still uses the old Color-Checker Values, which got changed 2014 or something like that, so watch out for that, if you have a newer Color Checker):
 https://www.imatest.com/docs/plain/colorcheck.html#:~:text=The%20GretagMacbeth%20ColorChecker%20is%20an%208%20x%2011%22,controlled%20pigments.%20Patches%20have%20a%20smooth%20matte%20surface.