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CineStyle for Canon EOS DSLRs

7 August 2011 26,109 views 14 Comments

Contents

Introduction

If you haven’t seen it already, Technicolor have released a custom Picture Style called Cinestyle for the Canon DSLRs.

http://www.technicolor.com/en/hi/cinema/filmmaking/digital-printer-lights/cinestyle

 
Apparently Technicolor have been working on this for the last year in an attempt to bring the Canon DSLRs more in line with other digital film cameras such as RED and the Alexa. The Cinestyle profile produces a very flat looking footage that retains a lot more detail in the darker areas. Technically speaking, it encodes the images received from the sensor into log colour space. Anyone used to working with raw footage from film will recognise the flat grade look to the footage. The aim is that it produces footage that is much easier to colour correct while retaining as much quality in the image as possible.

This post is an attempt to try to collate and filter as much up to date and correct information about Cinestyle and the practicalities of using it with the 5D MkII. There seems to be a lot of misunderstanding out there about what this is all about, particularly when it comes to working with lookup tables, or LUTs. (Nobody’s perfect though, so please leave a comment if you think I’ve got something wrong myself!)

Much of this information I’ll be sourcing from this thread on the Cinema5D forum. I’ll try to provide links as I go through to give proper credit and so that you can read the posts for yourself. If there are any dead links, please let me know in the comments.

Why use Cinestyle?

So first thing’s first; what are the benefits of using Cinestyle? Well, shooting in log colour space means that you retain more information in the darker and brighter areas. Note, that this doesn’t mean that you’re suddenly achieving greater dynamic range. The chip on your camera hasn’t changed and so you can’t magic dynamic range out of nowhere. All it means in practice is that you are getting better detail in the dark and light areas within the existing dynamic range.

All this messing around with the colour space is done before the lossy stages in the camera i.e. H264 compression (Source: post by Matt Thomas) which, of course, makes sense as otherwise it would be further degrading the signal.

The thing worth noting about H264 compression is that it is most aggressive at the low and high ends of the luminosity range, so by using the log colour space, it is effectively moving the valuable colour information away from the nasty compression artifacts. Again, Matt Thomas explains the concept very well here. He says:

The principle behind CineStyle is to move your shadow details up, away from the more destructive shadow region, which the H264 CODEC will damage more aggressively. By moving your “blacks” up into the lower mids, you will have more compressed data devoted to subtle gradations from the h264 CODEC. The same is true for highlights. By keeping the contrast very low, it allows for your highlights to be moved further from the destructive part of the h264’s white points, which, like the black points, have much less detail allowed by the CODEC than mid tones allow.

So I decided to put it to the test.

Video noise In dark regions

The following images illustrate the big advantage of using Cinestyle with video. It’s designed to test the amount of noise in the dark levels of the image.

The image on the right shows a still from the video output from the camera when Cinestyle is enabled. You can see, compared to the next set of images, the low contrast here produced by Technicolor’s picture style. CsEOS_VidCinestylePictureProfile
Cinestyle picture style (no LUT)

Once the lookup table is applied (in the right hand image below), the result is very similar to the video produced by the Normal picture mode (below on the left). More info later in this post on how to apply the lookup table.

CsEOS_VidNormalPictureProfile
Normal picture style
CsEOS_VidCinestylePictureProfile_LUT
Cinestyle picture style with LUT

This is where things get interesting. If we now apply a Exposure filter in After Effects with a value of +7.7 to both images, we get the following:

CsEOS_VidNormalPictureProfile_OverExposed
Normal with +7.7 Exposure
CsEOS_VidCinestylePictureProfile_LUTOverExposed
Cinestyle with LUT and +7.7 Exposure

You can see, even in the thumbnails, that there is noticeable banding in the image captured from the Normal picture style image (to see it more clearly, right click on each image and select “Open Link In New Window”). It’s pretty obvious that the Cinestyle video is giving us much more information in the dark areas.

What about taking stills?

Okay, this bit was a surprise… If you take a picture using the Cinestyle mode while using Jpeg as your storage medium, you get the flat low contrast appearance in the image. All fine so far. What is surprising however, is that if you set the 5DMkII to store RAW, there is still a subtle yet noticeable difference. Usually, changing picture mode (even switching to black and white Monochrome mode) has no effect on the RAW image at all. However, in this case, something interesting is happening with Cinestyle.

With the two images below, at first glance the RAW doesn’t appear to be particularly affected by Cinestyle. RAW files basically ignore most of the camera settings like picture profiles, white balance, etc., so this would be as expected.

CsEOS_PicNormalPictureProfile
Normal picture style
CsEOS_PicCinestylePictureProfile
Cinestyle picture style

 
However, if we now overexpose both images, we get this:

CsEOS_PicNormalPictureProfile_OverExposed CsEOS_PicCinestylePictureProfile_OverExposed

It’s a very subtle difference which you probably won’t notice unless you view the full size images side by side (again, just right click on each image and select “Open Link In New Window”). If you look in the darker areas, you’ll notice that the Normal picture profile hue tends towards red in the darker areas, whereas Cinestyle appears to retain the correct hue through to the darkest point.

Wow. So Cinestyle seems to be doing something genuinely funky with the colour processing pipeline in the 5DMkII. Something that none of the other picture styles do. This only goes to confirm that Technicolor must have been working very closely with Canon to implement Cinestyle.

Are there any disadvantages?

Yes, possibly. In tests I’ve done, it’s quickly apparent that there’s a black offset. A large number of posts online suggest that black is mapped to a value of 16. In my test however, it only appeared to be around 8. This would seem to be confirmed by the Cinestyle LUT. Going into After Effects and making a solid layer at RGB <8,8,8> and applying the Cinestyle LUT (see later), the resulting RGB value that the LUT returns is <1,1,1>, whereas an input of RGB <7,7,7> results in <0,0,0>.

If you want to see the black offset for yourself, the test is very easy to do on your camera and is noticeable just looking at the LCD viewfinder. Just leave the lens cap on and take two short bursts of video, one with Cinestyle, and one in Normal mode. Press the play button and flick between them using the front dial, you’ll be able to see that the black is obviously lighter in the Cinestyle footage. When I tested the colour values in After Effects, it gave values around 7 or 8 as the minimum.

Similar tests with overexposure showed that the white was not offset, i.e. with full exposure, it used the maximum white value of 255. The offset in the black helps to avoid the more destructive compression of H264, but it also means that we’re losing colour resolution. This could result in banding issues if the colour grading is pushed too far in the mid tones where there might not have been issue before. For a good example of this, see this post by Richard Crook. Also, check out this video which discusses some of the problems involved using flatter colour profiles.

Which then leaves us in a bit of a dilemma. Should we be using Cinestyle at all? Unfortunately, I don’t think there’s an easy answer. I’d say that it depends on what you’re going to shoot. As Richard says in a later post:

If you are shooting a situation like, for example, in a forest…then banding is a moot point because there is so much texture it doesn’t matter. But shooting a low dynamic range subject like the sky or a wall, both with subtle gradients, a flatter profile like Cinestyle isn’t a good choice.

That makes sense to me. From a post production point of view though, it’s a bit of a pain, because if the camera operator is switching between different colour profiles on a per shot basis, then that’s one more thing you (or the clapper loader) has to keep track of.

Installing Cinestyle

To install the Cinestyle profile, you first need to download it from Technicolor’s website.

Once you’ve got that, you need to make sure that you have the EOS Utility installed on your machine. It’s supplied on a CD that came with the 5DMkII, but if you don’t have it handy then you can download EOS Utility from Canon US. The only issue with downloading it, is that it’s engineered by Canon to be an update-only install (why do they make things so hard for us!!). Luckily, it’s quite easy to turn the update installation into a full one. Full instructions can be found on Keith Cooper’s photography website.

The step by step instructions for installation can be found at Technicolor, but for your convenience, I’ve copied them in below.

  1. Ensure that EOS Utility v2.6 or later is installed on your computer
  2. Download the Technicolor CineStyle Picture Style file
  3. Connect your camera to your computer using the appropriate USB cable
    Note: for the EOS 5D Mark II you may need to set “Communication” to “PC connect.” in the camera’s menu
  4. Start the Canon EOS Utility
  5. Select “Camera settings/Remote shooting” on the main window
  6. Once the capture window opens, click the camera icon
  7. Click “Register User Defined style” under “Shooting menu”
  8. Once the new page “Register Picture Style File” opens, select one of User Def. 1, 2 or 3 at the top of the new page
  9. Click the open file icon
  10. Select the CineStyle.pf2 file you’ve just downloaded
  11. Click on OK

Setting up the Canon 5DMkII

There are a couple of subtle issues that you should be aware of to maximise your the quality of your footage. Neither of them are killers, but it’s a good idea to be aware of them.

The first thing to know (and the source for the following explanation is a great in-depth article at Josh Silfen’s website), is about how the 5DMkII works with the ISO setting. To paraphrase Josh’s article, the sensor in your camera has an intrinsic ISO setting associated with it of ISO 100. The ISOs that are at doubling sensitivities above this (i.e. 200, 400, 800, 1600, 3200, 6400) are also native ISO’s (derived, I suspect, from directly manipulating the way the sensor is employed). All the other ISOs are based on these and are either 1/3 stop over or under exposed.

For example, it is approximately true that:

ISO 320 = ISO 400 x 2^(-1/3)
ISO 500 = ISO 400 x 2^(+1/3)

This is a digital process after the image has been captured, and means that from a visual point of view, the pull down ISOs of 160, 320, 640, etc. will appear to have less noise. Unfortunately, the stopping down also means we have less dynamic range, as the highlights lose 1/3 of a stop as well. We end up with a trade off, and so it’s definitely something to be aware of. Please read Josh’s full article on this for more in depth information.

The other thing to know, is why you probably shouldn’t use Highlight Tone Priority. Again, Josh comes to our rescue with another brilliant post on this which you can find here. Essentially, the message is that Highlight Tone Priority doesn’t give you any extra dynamic range, and you have a little less control over exactly what the camera is capturing. You’re doing colour correction in-camera, rather than in post.

Shooting with Cinestyle

The main thing to know is not to set the exposure for your video with the CineStyle profile enabled. As Richard Crook notes in this post, going a stop either side of the correct exposure makes little difference to what you can see in the camera’s LCD screen. That’s a big change to be unaware of.

So unfortunately that means you’ll need to set up the exposure using the Normal picture style, and then switch to Cinestyle for capture. Not ideal. It’d be great if it were possible to capture using one style and preview using another, but I guess we’ll have to keep wishing.

Post processing the footage

Once you’ve taken your video, what’s the best way to process it? RareVision’s tool 5DToRGB will convert your H.264 quicktime movie into DPX files using some sort of clever processing technique to achieve better results than the standard quicktime codec for decompression.

If you’ve got a lot of files to convert, you can use this batch tool from Noside to convert multiple videos at once using 5DToRGB.

The footage that comes out of the camera looks very flat. That’s why Technicolor provide a lookup table (LUT) to view the footage with. In order to use it with After Effects, you can download for free Magic Bullet LUT Buddy 1.0. This allows you to apply the LUT to a layer as an effect. There seems to be a couple of issues with LUT Buddy crashing, but it is possible to work around the problem by converting the LUT to a different format. More information on this fix from Lars Steenhoff’s blog post.

Working with LUTs

There seems to be a fair bit of misunderstanding in the online DSLR community about what LUTs are and how to work with them. It’s understandable, as they’re not something most photographers have to deal with, so there follows a brief explanation.

In an ideal world, before manipulation in post with CGI and compositing, all footage should be converted into linear colour space (sometimes also called “scene referred” colour space). Linear colour space is where the brightness of a pixel is directly proportional to the amount of light that it received in the camera, i.e. a doubling of pixel intensity, means double the received light.

Most people are used to using images that are encoded in sRGB colour space. This has a gamma correction curve of approximately 2.2 encoded into the intensities so that it displays correctly on a monitor (which has a response curve of 2.2). But this means that for an sRGB image, if a pixel receives double the intensity in camera, it won’t be double the brightness in the image.

The problem with using and manipulating sRGB images is that a lot of mathematical operations in compositing don’t work due to the maths being affected by the baked in gamma curve. On the other hand, although we can use linear images, they don’t look very good when directly viewed on monitors and it’s very hard to make aesthetic judgements.

This is where LUTs are a big help. They allow us to view images in one colour space (i.e. sRGB), while the software processes them in another (i.e. linear). It’s a little bit like looking through a pair of sunglasses; the image isn’t being being changed, but it’s altered at the last minute for your benefit so that you can see it properly.

So in VFX, LUTs are used all the time to work with footage in linear colour space during compositing. It means that the software can do all it’s operations correctly in linear space, while we can view the result through the LUT that turns it into something that we can view properly on our monitor. In addition, we’ll often encode a grade (colour correction) into the LUT so that we can see how the final image will appear once the colourists have done their magic on it and applied the final look.

The problem with software like After Effects, is that their colour space handling is extremely confusing to deal with. Seeing as After Effects doesn’t directly support LUTs (as pointed out in the comments section, CS5 now has a plugin to apply LUTs in a similar way to Magic Bullet, unfortunately there’s still no way to load a LUT into the colour management settings), then I’d generally recommend applying LUT Buddy to an adjustment layer at the top of the main composition. As you work, everything can be viewed with this applied.

Colour corrections can be done before or after the LUT layer. In fact, you can even throw away the LUT altogether and do your own grade from scratch. It’s a little bit arbitrary for reasons explained in the next section.

What about Linear Colour Space?

That’s a very good question. The big problem with Cinestyle is that the supplied LUT converts from a log based colour space to something very similar to the original REC 709 colour space, and NOT linear. A lot of people online are saying that the LUT does convert to linear, but it doesn’t as the final result still looks perceptually correct on a 2.2 monitor. This means that it must have a 2.2 gamma correction applied to it, and so it’s probably REC 709 or sRGB.

As of this moment in time, Technicolor have not released a LUT to go from Cinestyle to linear. This is a bit of a major issue for anyone wanting to composite with this footage. In theory, it should be possible to use the LUT to convert from Cinestyle to REC 709, and then convert from REC 709 to linear, although I’ve not tested it’s accuracy yet.

Where do we go from here?

In lieu of Technicolor releasing a Cinestyle to Linear lookup table, I believe the next step is to look into measuring the camera response curve and deriving my own lookup table to convert to linear space. I believe a paper exists by Paul Debevec that illustrates this process. I’ll post a link if I can find it.

A final plea

Dear Technicolor. Cinestyle is great and opens up our ability to capture higher quality video, but it’s severely limiting if the proper technical details aren’t released to the community to allow us to use it in the correct way. The lack of a clear specification of what the supplied LUT actually does (i.e. the destination colour space) is a surprising omission in this release. Publicly releasing a LUT to go from Cinestyle to Linear would be a simple solution to this problem.

Please, give us more information!

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14 Comments »

  • Itai said:

    Hey
    Thanks for the informative article!
    After Effects certainly support LUT, in the popular 1d & 3d lut formats.
    You simply add the “apply lut” plug in.
    The problem is that the Cinestyle lut is of the .mga type, which After doesn’t recognize… (I am now stuck with a lot of footage shot on Cinestyle).
    Thanks
    Itai

  • AndyN (author) said:

    Hi Itai,
    Thanks a lot for the correction about AE LUT support, I’ll update the post accordingly.

    Cheers!
    Andy

  • AndyN (author) said:

    Looking into this further, it appears that LUT support through the plugin you mention is only available in CS5 and above.

    Unfortunately, it still doesn’t let you load a LUT as a custom colour profile into the colour management settings which is slightly frustrating, as that would integrate it into the colour workflow much more tightly.

  • Sergey said:

    It feels like I’m trying to catch a long gone train, but at the end of your absolutely informative article (it is still to me) you ask question. I spent hours searching for a better styler a better picture style for my 5d3. All technicolor’s and red giant’s LUTs didn’t work for me. Too complicated and time consuming. The solution for CineStyle came absolutely accidentally. I always use 5DtoRGB Batch and never paid attention that it can work directly with technicolor log file. So instead of Post processing “None” chose “Technicolor” and you’ll get your .mov file ready with S-curve applied. It looks just great! Color correct it as you wish…

  • AndyN (author) said:

    Thanks for the info Sergey. That’s interesting to know that 5DtoRGB can do that.

    I would still give my right arm to know how to get a linear image out of it though, as that’s what we need to use if we’re doing CG and compositing.

  • Sergey said:

    … unfortunately I’m not so deep in these things. I just enjoy playing with it and having fun. I judge things with my eyes mostly and I have 27′ iMac for this.
    5DtoRGB updated his toy recently to an amazing extend and now it gives so much better outcome. Note – I don’t sell things. After setting CineStyle on my camera, I filmed my grandson with a new settings and later understood that it wouldn’t be simple to get nice looking image.
    After 5DtoRGB it looks great. A bit too saturated as per standard settings of CineStyle, but it is fixable in preset. It is about 250 bit rate and goes smoothly in Premiere Pro.
    The thing is that I found ‘ShutterDown” PP which is almost like Cinema PP but one or two stops brighter, keeping tonnes of details and it is not flat. It works for stills too. I applied some severe curves and it handles well. It is free and time safer at the end.

  • Pablo van Wetten said:

    Hello Andy.

    I am shooting a short movie and have a 550d a 600d and a 5dmkII.
    I really need to understand what picture style is best for my DOP, who is great with light and worked a lot with 35mm film but not so much with DSLR. We want to grade the movie to B&W in resolve afterwards. I understand your issues with Cinestyle for outside shots (banding etc.)
    We can shoot the outside shots without cinestyle and the interior shots with netral for example, is this wise you think?
    I also have to take into account that my DOP will see a picture that is very flat when we use cinestyle and hopefully he will still feel that he is creating the image on the set rather than have to squint and imagine what the graded shot will look like after post.

    What are your thoughts?
    Your help or from anybody else is very, very appreciated, there is so much noise out there, dslr ‘filmmakers’ sure like to pretend they know a lot but are generally just very excited about nothing imho and honestly 90% of the so called ‘grading’ I see out there is truly horrible, unimaginative and very quasi 35mm (the idea is still that everything should look like 35mm film while I am simply looking for a beautiful image) but on your page there is a sense of calm actual ‘understanding’ what is going on inside and outside of the camera that is very pleasant.

    Regards,
    -pablo

    Ps if you are in the dark about what the best options are, can you recommend someone who has had the same dilemma with these 4 factors dslr/pp/resolve/b&w

    Thank you again!

  • AndyN (author) said:

    Hi Pablo,
    Thanks for your message.

    We can shoot the outside shots without cinestyle and the interior shots with netral for example, is this wise you think?

    It’s not about inside versus outside, it’s about the amount of contrast and detail. For example, if you shoot a plain wall where you’ve got very little variation in color in the midtones, then you’re a little more likely to observe banding with Cinestyle. You won’t notice this happening if you’re shooting something with a lot of detail in it.

    If your DOP hasn’t shot much on a DSLR or worked with Cinestyle, then it’s really worth trying to get him some time to do a test shoot so he can get a feel for how to shoot with it. If he wants to get fast feedback, you might want to consider tethering the 5D to a laptop using the Canon software, so you can transfer the movies on the fly and bring them into something like After Effects to see if there are any issues.

    I also have to take into account that my DOP will see a picture that is very flat when we use cinestyle

    I’d strongly recommend that your DOP doesn’t light and expose his shots with the Cinestyle profile active. It’s too easy to under or over expose when viewing a flat colour profile. Always disable Cinestyle when setting up lighting and exposing, and just remember to switch back to it before you start recording.

    I’m not aware of any issues with doing a final grade down to black and white. But if you have any doubts, you should get in touch with a professional colourist who has graded this sort of footage before, as they’ll be able to give you a good idea of it’s limitations.

    Hope this helps,
    Andy

  • rhys said:

    Hello Andy,

    A comprehensive and well written piece, the linear conversion part being the reason I stumbled upon your blog.

    Cinestyle to linear…is there a solution you have been using that is right or comes close? I need to comp cgi into dslr footage.

    Kind Regards

  • AndyN (author) said:

    Hi Rhys,
    I think the best bet is to use the Cinestyle LUT and see how the result of that compares to a photograph of the same subject. I’d suspect that it’d be very similar in which case it would be reasonable to assume that Cinestyle LUT is converting to something approximating sRGB.

    From there you can convert it back to linear for comping. Ideally use Nuke, as it’ll keep as much precision as is possible in the process.

    Of course, this still isn’t ideal, but it’s the approach I’d consider trying. Hope that helps.

    Cheers,
    Andy

  • PaulJBis said:

    Hello:

    First of all, *thank you* for this post, the best summary I’ve seen anywhere about Cinestyle and its use in VFX. I only disagree with you in one thing: the idea that you can color grade “before or after” the LUT layer. The entire purpose of shooting in Cinestyle is to get more detail in the shadows and highlights… but if you apply the LUT (a S-Curve really) and then grade, aren’t you already crushing your blacks before the image reaches the color correction tool? Doesn’t that defeat the whole purpose of using Cinestyle?

    It’s a misconception that I’ve seen in a lot of forums, and it surprises me, because there’s a very simple way to test it: shoot a piece of footage using Cinestyle, and then, in After Effects, apply an Exposure filter with +1 or +2 before the LUT. Then move it after the LUT, and compare the amount of detail that you get in the shadows using both ways…

    …Which leads me to the reason I’m writing: I’m currently on a project where I have to composite CGI over Cinestyle footage, just like Rhys above. The obvious way to do that would be to follow your suggestion and turn the footage into linear, then composite, and then color grade… but that would fall right into the problem I’ve described. I’d like to color grade taking advantage of the extra detail in the Cinestyle footage, which would imply adding the LUT as a last step… but I also need to composite it with the CGI footage, which is in linear, and obviously can’t neither receive the same color grade than the Cinestyle footage nor the same LUT.

    What to do? I’ve been thinking about this puzzle, and haven’t really found a solution. Do you have any ideas?

  • AndyN (author) said:

    Hi Paul,
    Thanks for leaving a comment. Apologies for the delay in replying. I’m glad you found the article useful.

    To address your first issue about grading before or after the LUT, I’ll stand by what I said and say in theory it doesn’t matter, it’s arbitrary. In practice, it may not be. There are two issues that come into play:

    1) The first is software dependent and is all about how well your compositing software maintains accuracy. If you’re using something like Nuke, it really isn’t a problem. In Nuke you can apply a gain of 0.0001, followed by a gain of 10000 and you’ll get exactly the same image. In After Effects, it wouldn’t surprise me if you don’t (I’ve not tested it though). So in that respect, it’s possible that there may be a difference in quality between the two. However, it’s unlikely that it would be too noticeable if we’re talking about some basic grading.

    2) Applying colour correction before or after a LUT means that the colour values that you’re trying to adjust are appearing in a different location in the histogram. So, as you rightly said, applying an exposure or gamma adjustment for example, will get you a completely different result visually.

    *But* unless you’re losing quality and you start to see banding, you can do whatever you like to get the result you’re after. For you, that’s about keeping detail in the shadows, for others it might not be. If you understand enough about what the colour correction is doing, as you clearly do, then you can make an informed choice about doing grading before or after. But in the end it comes down to it being an aesthetic choice. There is no right or wrong as long as it looks good and you’re not getting banding.

    (Note, that if you were using Nuke, we wouldn’t even be talking about before vs. after. The common workflow in Nuke is that you apply a LUT as soon as it is loaded that takes it into Linear space. It means that everything you do in your comp is done in Linear. You then dynamically view your comp through a Rec709 or sRGB LUT so that it looks correct on your monitor as you work. Finally, you save out the result of your Linear comp in whatever colour space you want. Since Nuke is really good at maintaining floating point accuracy, it’s really not an issue moving between colour spaces.)

    So to address your second question. Always comp in linear. Any other way is… well… just wrong! You need to convert your footage using the LUT first, then do a Rec709 (or sRGB, you’ll need to test) to Linear, and comp using that plate. If you make sure you save your linear plate as a floating point format such as OpenEXR, 32 bit TIFF, or dpx then you should retain all your accuracy (again, test it). Once you’ve comped it in linear, you can convert it back to sRGB or Rec709 and you should still see all your details in the shadows. If you don’t, ditch After Effects and get a copy of Nuke!

    Basically, at each stage, you need to make sure that you’re retaining full floating point accuracy, and the only way to do that is to test each stage of the pipeline. Whatever you do to the image, just make sure you can undo it again while retaining full quality.

    Hope that helps,

    Cheers,
    Andy

  • PaulJBis said:

    Hello:

    Thanks for your answer. After my first post I did a few more tests, both in After Effects and also in Nuke, and I found that you are right: if you work in 32-bit float through the entire pipeline (AE can do this too), there *should* be no problem keeping all the detail (with one exception; more later). The only thing I found is that you have to drive the grade tools quite harder if you grade after the curve: for example, let’s say I add an exposure tool with +3 stops before the curve; if I put it after the curve, I have to push it to +5 stops or so to get the same result.

    (This is what was leading my astray in the beginning: I put the same exposure tool before and after the curve, and wondered why the image looked much darker in the second case…).

    Due to the above, my personal preference is still to add the LUT/S-Curve last and grade “under the curve”, following the philosophy in this post (specially the next-to-last paragraph):

    http://mikemost.com/?p=251

    However, this leads me to another problem: once you’ve done the compositing in linear, you have to convert back to Cinestyle log and export, in order to grade along with the rest of the footage. What I’ve found in this step is that the Technicolor provided LUT isn’t precise enough: if you apply it to the images and then invert it and apply it again, there are clearly artifacts. The 32-bit internal processing of the software isn’t losing information, but the LUT is. (Actually, if you open it with a text editor, there are only 32 distinct values in the curve!)

    Thus, I’m experimenting now with using log2lin (or the Cineon Converter in AE) to convert the footage from log to linear. So far I’m not being 100% successful, but I’ll keep trying. In the meantime, if you (or anyone else) have any insights about the subject, I’d be most appreciative.

  • George Tudosi said:

    First of all, thank you so much for a comprehensive compilation of knowledge.

    There is a great software, Magic Lantern, which particularly helps to solve exposure problems. Using it you can see not only a live histogram while shooting, but moreover, it implements a number of advanced instruments, say, waveform display, vectorscope and zebras. It can also switch color profiles automagically—one for scene preview and the other for recording.

    And what about linear color space? Of course you may use the supplied LUT. There were even more “powerful” tools such as Technicolor Color Assist which seems to be abandoned now. But look, there’s a “Cineon converter” in Adobe Premiere video filters. It seems to do the right thing—it can convert from log to lin. I haven’t investigated it in details yet but the picture it produces looks very natural and have very little noise.

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