For v3.1 I have been working on 'responsive design' principles, which basically aims to allow LUTCalc to be useable regardless of the screen size. LUTCalc is fundamentally a web app, built upon HTML, Javascript and CSS. Lastly, I've gone through an overhaul of how the user interface (UI) is expressed. This sits after all your other tweaks and customisations and allows you to convert your look from one colourspace (eg Rec709) for use in another (eg DCI-P3). The other most obvious feature is what I'm calling the 'Display Colourspace Conversion' tool. If, however, all the OOTFs, EOTFs, OETFs and such are nothing new to you and you find that I'm committing some obvious howlers - please do let me know! If all that sounds like gobbledigook, uh-huh! HDR is unquestionably becoming important, but the days are early, the concepts potentially such a break from today and the opinions and tastes still so undecided that I see these options as more for information to most people for now. Hopefully it should now be flexible and correct. To do all this I decided the best option was to start again from scratch with the HDR code.
I have also included options with HLG to choose exposure scaling between the standard (90% white target maps to 50% HLG) and the BBC suggested reference (90% white target maps to 73%).
LUTCalc's model is scene referred, so for the PQ options I have included the PQ reference OOTF, the HLG reference OOTF (which should be used when converting between HLG and PQ and back) and an EOTF-only option. I've been reading up as much as I can about the Rec2100 PQ and HLG colourspaces, and in particular looked to understand the fundamental difference in approach of PQ as a display-referred colourspace against HLG as a scene-referred one. However, including equations for technical papers and implementing useful, appropriate options are two different things an I have now tried to put LUTCalc into the right position. LUTCalc has long included various high dynamic range curves, including the two which are establishing themselves as standards: Perceptual Quantisation (PQ) and Hybrid-Log Gamma (HLG). I've been playing around taking and analysing test images on an a7s the result of which is my estimation of the Cinegamma 3 and Cinegamma 4 curves (Cinegammas 1 and 2 being renamed Hypergammas).
This update features a couple of new curves, some important changes to the way others work, a new tool for targeting different displays and the start of changes to the interface.įirst, a relatively simple new feature. LUTCalc v3.1 Update - 1t June 2017 - HDR, Cinegammas, Display Colourspace Conversion and responsive design More details about LUTCalc can be found in the ' Features' section Back To Top
This is an ongoing process and I am grateful for the help I have had in checking results and discovering when I have made mistakes! LUTCalc allows you to set all levels as you wish, but also offers simple presets to help consistency in various applications.
I have also come to realise that at present it is far too easy for LUTs to behave inconsistently between bits of software (or cameras). I have worked to make the tools familiar to me in my work with film and video cameras for example colour temperature can be set directly but also with a CTO / CTB slider akin to lighting gels. Many of my clients do not currently want or need log, and I frequently bake-in my personalised looks developed with LUTCalc. The charts and exposure values have also helped me to understand the way that modern cameras handle wide exposure ranges giving me good, consistent results. If shooting log I also make grading versions so that post can start off working with 'my' look. I use it to create MLUTs for the Sony F cameras I currently most often use. I have written LUTCalc from scratch to help me with my day to day work.
My name is Ben Turley and I am a professional lighting cameraman and DoP in the UK. What began as a hobby gradually became more of an obsession which has developed into a flexible tool for creating and then shooting with 'looks'.
It started out as a simple spreadsheet for generating S-Log2 exposure shift LUTs for Sony's F5 and F55 cameras. LUTCalc is a desktop app for generating, analysing and previewing 1D and 3D Lookup Tables (LUTs) for video cameras that shoot log gammas.