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Everything posted by cameronrad
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My personal preference is to use gamma to describe pure exponent functions. Unless talking about "Film Gamma" So 1.0, 2.2, 2.4, 2.6 etc. Or linear gamma (1.0), Rec.709 Display (2.4), .DCI-P3(2.6) Then I reserve tone curve for more complex things, like camera curves, transfer functions, etc. sRGB isn't a pure 2.2 function, so I don't say the gamma of sRGB., but rather the tonal response curve or transfer function of sRGB.
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Tone curve would likely be best generalized description. There's definitely some confusion around terminology here Gamma is really broken down into 3 parts. Input — OS/Correction/Intermediate — Output There's an applet here where you can visualize it, as well as some better explanation of gamma correction: https://sites.google.com/site/marclevoylectures/applets/gamma-correction
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Blade Runner, color grading
cameronrad replied to Thomas Singh's topic in Editing , Color grading & Finishing
The look is developed in camera and on-set, then refined in post. -
There are "Printer Light Hotkeys" in resolve, they just adjust the offset tool.
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And in Photoshop this is the "Constant" slider in Channel Mixer. Or the Brightness/Contrast tool set to legacy mode.
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Contrast of 3D LUT
cameronrad replied to Thomas Singh's topic in Editing , Color grading & Finishing
I think tone curve would be a bit more applicable. Contrast is used to describe the differences between things like brightness or color. For instance an example of high tonal contrast, but low color contrast is the bleach bypass look. -
LUT based on print data
cameronrad replied to Nicolas Hanson's topic in Editing , Color grading & Finishing
Thank you so much Mr. Bogdanowicz! I will definitely look into that! I often times wish I knew about the Munsell Science Lab when I was in high school so I could've followed that path. I've thought about taking the summer program actually. I never knew there was an entire field of color science and didn't discover my passion for it really until a few years ago. It's been a slow/tedious but addicting process learning this. Unfortunately I do wish I practiced mathematics more and didn't forget so much since H.S. I also need to improve my ability to work with code and command line utilities vs. relying on GUI based software. I'll try to find an apprenticeship/internship around me to better understand this field. I'm in Los Angeles, so i'm fortunate to be surrounded by some of the best. I've messed around with argyllcms before but wasn't sure if it was suited to the task. I've also thought about messing with this toolset http://colour-science.org/ however I still need to become more comfortable with command line tools. There seems to be a lot of misinformation, misunderstanding, and overall bickering between between the ICC (Stills/Computing) community and 3DLUT/Motion community. I've read about 3DLUT/Table based ICC Profiles and remember a few years ago the ICC community was examining motion picture workflows, but it seems like they've abandoned that. http://www.color.org/ICC_Chiba_07-06-19_PM_DMP_Float.pdf It seems as though motion is pushing towards the ACES approach, which from my understanding shares a lot of similarities with the ICC Color Management approach. I may be wrong but I think at the core, a lot of people misunderstand how the color management systems work. To me it seems as though ACES is a more explicit color management system than ICC but principle is the same. Transform from color space to another. The differences being how integrated the are into background processes. ICC working more in background, ACES working more through defined parameters. That said I hope something is agreed between the two industries. Over the past few years I've only really seen developments in the motion world and I wonder if the stills world will follow in that direction. Do you have any preferences on camera profiling methods for stills cameras? Adobe seemed to abandon ICC profiling for DSLR/Still Camera RAW files and now uses a DNG/DCP Profile with a "2.5D LUT" (Hue/Sat Tables) however uses ICC as working/output spaces. Adobe Camera RAW/Lightroom internally use MelissaRGB (ROMM Primaries/Linear gamma aka RIMM) as a working space but convert to an output "working space" like AdobeRGB when processed. Capture One still uses ICC, however they have a unique way of developing and implementing theirs. They are LAB based instead of XYZ and they are applied similarly to a LUT, whereas the RGB Data is just assigned with a new profile instead of converted. One of the most desired looks/aesthetics amongst still photographers is the skin tones and overall color found in certain Kodak film stocks like Portra or Ektar as scanned through a Frontier or Imacon scanner. http://www.lettherebefilm.com/exposures/ Like the motion world, we have a plethora of "film emulation presets" for sale. But unlike cinema, with stills presets none have been properly created with proper data collection. They typically are just 1D Curves and crude adjustment presets for software like Lightroom. Although I personally don't apply "film emulation" to my still work, I am intrigued at the possibility of creating camera profiles/LUTs/ICCs/etc to help remap my digital cameras color response to a more "natural", subtractive color looking color palette. By the way all your patents are awesome. I'm always blown away when I read them and the descriptions for the Kodak Look Management System and the color management systems you helped develop. -
Log image, linear gamma?
cameronrad replied to Thomas Singh's topic in Editing , Color grading & Finishing
Check out these resources: Cinematic_Color_VES.pdf https://www.cambridgeincolour.com/tutorials/gamma-correction.htm -
LUT based on print data
cameronrad replied to Nicolas Hanson's topic in Editing , Color grading & Finishing
You rule Mr. Bogdanowicz , I constantly reread all your patents and articles on your site trying to further understand color science. It's taking a while as I'm relearning math and still don't know how to code to really to implement these techniques. Do you have any books or resources you recommend? Or any GUI friendly applications other than Lattice/3DLUTCreator that let you manipulate and apply some of these transformations. -
Image Processing Pipeline 2 http://www.red.com/news/upgrade-your-workflow-with-ipp2-reds-new-image-processing-pipeline
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I think this will work: HW_ShowLUT_LogC_2_Rec1886_16.cube.zip
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I'm pretty sure most of the colorists that are truly familiar with 3DLUTs care about gamut. Maybe not the newer inexperienced colorists.that just know lut's for looks. Before the whole look LUT thing, they were for technical color space transforms. If those LUTs were just transforming curves, they wouldn't need to be 3DLUTs and could just be 1D LUTs/Curves. I think some of the good technical information has pushed in oblivion by clickbaity tutorial blog posts or people just putting out misinformation. I imagine the adoption of aces would bring more people's overall awareness back to colorspace transforms and gamut, gamma, etc.
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Check out these benchmark charts: OpenCL: http://browser.geekbench.com/opencl-benchmarks Cuda: http://browser.geekbench.com/cuda-benchmarks
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Just want to mention that hardly anyone in stills actually uses LAB mode. A lot of the techniques proposed by Dan in his book we're later proven to be wrong or misinformed. In stills we typically will leverage LAB mode math in the form of blend modes, but you hardly see anyone actually working within LAB mode. Usually retouchers go through a cycle of experimenting with it hoping to find secrets or techniques not accomplishable with other modes, however end up back using Trichromatic Color Models like RGB vs. opponent color models like LAB as a working space. LAB is great when it's used for the underlying mathematics for color transformations or blend modes. For instance, luminosity and color blend mode in Photoshop. A lot of the earlier LAB mode techniques in photoshop were proposed before those blend modes became available. One big thing I hear is ability to control luminance independent of color. Which is no different than using luminosity blend mode. Another is being able to stretch color channels (saturation) without effecting luminance. Which is like color or saturation blend mode, however you're not as constrained with boundaries of rgb gamut though you may clip colors.
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Depends on who it's from. Some companies like Koji create their LUTs from densitometric readings of films. However I don't think most people selling LUTs nowadays go through that process/effort. Likely they are just like the people in the stills world selling presets/looks. Basically either repackaging others work with small modifications and reselling them, like photographers do with VSCO. Or they are just exporting a global look into a LUT in resolve, 3dlcreator, photoshop, lightroom, etc. Lightillusion looks to have worked with Koji and Looklabs. Maybe Steve Shaw can give some more accurate insight into this process. https://www.lightillusion.com/film_profiling.html
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Color Grading Two Cameras To Match
cameronrad replied to Cody Board's topic in Editing , Color grading & Finishing
Unfortunately that assumes one has colorchecker references available, unless they generated the matching LUT beforehand. I believe ACES goal with camera IDTs is to solve that standardization issue. OP could try a couple OCIO transforms. For instance a transform like this > followed by a balancing a adjustment > followed by a cineon to srgb/rec709 transform -
Color Grading Two Cameras To Match
cameronrad replied to Cody Board's topic in Editing , Color grading & Finishing
I don't think that's the OP but I agree. All the neutral picture style really is, is a tone curve + hue/sat. I used an slog to srgb lut, followed by an s-curve, followed by hue/sat layer in my PSD. Those should be easy to copy in any other application. -
I'd love to assist/apprentice for you. Unfortunately all my experience is in stills retouching/color. You've been my fave colorist for a while. Actually are the main reason I even know what a colorist is.
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Color Grading Two Cameras To Match
cameronrad replied to Cody Board's topic in Editing , Color grading & Finishing
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From what I've read and seen, the ACES system seems pretty similar to the ICC system in photography. These screenshots are from the VES Practices and Standards book and show some of the structure of both systems. ICC: ACES: Typically with stills to match different cameras, I create either ICC profiles, DNG Profiles, or LUTs under different lighting (Daylight, Tungsten, Fluorescent) with a Colorchecker SG chart and will use that as a baseline adjustment for the cameras. I know with Resolve you can use the 24 patch colorchecker, however from my experience with stills I don't think that 24 patches is nearly enough to get a quality match in my opinion. This also seems like a good target for matching/calibrating. http://www.basiccolor.de/basiccolor-dcam-target-en/ It has more patches than a Colorchecker SG and it has a blackbox target
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B/W Rgb values in film stocks
cameronrad replied to Abby Bader's topic in Editing , Color grading & Finishing
On the topic of Fujifilm and Film Emulation/Simulation, check out section 4.2 http://www.fujifilm.com/about/research/report/056/pdf/index/ff_rd056_009_en.pdf -
B/W Rgb values in film stocks
cameronrad replied to Abby Bader's topic in Editing , Color grading & Finishing
Not at all. I believe the original source of these numbers was actually this blog post http://www.prime-junta.net/pont/How_to/100_Curves_and_Films/_Curves_and_films.html from years ago. Which may have actually grabbed those numbers from some old photo forums like https://luminous-landscape.com/bw-better/ or http://www.russellbrown.com/tips_tech.html -
B/W Rgb values in film stocks
cameronrad replied to Abby Bader's topic in Editing , Color grading & Finishing
I think there's some extra digits to those numbers? I believe these are the numbers you're referencing: http://www.markushartel.com/blog/learn-from-markus/channel-mixer-settings -
Green channel values
cameronrad replied to Nicolas Hanson's topic in Editing , Color grading & Finishing
Coming from stills, I've read slightly different. I've read that's how "Luminosity" is calculated rather than "Luminance". However there seems to be confusion in terminology between stills/photoshop world and rest of the world. I think photoshop/stills world is incorrect and a bit behind/backwards to be honest. via http://www.cambridgeincolour.com/tutorials/histograms2.htm