--- title: "Log Footage, LUTs and Color Spaces | colorgrade.video" description: "Log footage, LUTs and colour spaces explained: input transforms, Rec.709 vs Rec.2020, technical vs creative LUTs, 3D LUT sizes and interpolation, HDR basics." url: https://colorgrade.video/color-grading-tutorial/log-footage-and-luts --- 1. [Home](https://colorgrade.video/) 2. [Color grading tutorial](https://colorgrade.video/color-grading-tutorial) 3. Log footage and LUTs Chapter 8 of 13 · Advanced · 9 min read # Log Footage, Color Spaces and LUTs Explained Log footage confuses people because it looks wrong on purpose. It is flat, grey and pale straight out of the camera, and it only looks right after a conversion that most phone apps and editors hide from you. Once you understand what that conversion does, a lot of grading problems disappear: looks that turn muddy, LUTs that clip, skin that goes strange on one camera but not another. This chapter explains the ideas underneath: what a log curve and a wide gamut are, how colour management moves footage from the camera’s colour space into a working space and out again, how Rec.709 and Rec.2020 differ, and what a 3D LUT really contains. If you just want to convert a clip, the [log to Rec.709 converter](https://colorgrade.video/log-to-rec709) and the [Apple Log to Rec.709 page](https://colorgrade.video/apple-log-to-rec709) do that in a few clicks. Here we go into why. Video guide ## Log Footage Color Management: Convert First, Then Add a Look Duration: 0:39 Your browser can't play this video. [Download the MP4](https://colorgrade.video/media/videos/log-footage-color-management-before-a-look/video.mp4) or read the[full transcript](https://colorgrade.video/videos/log-footage-color-management-before-a-look). Chapters 1. [ Play from 0:00 Log as recorded ](https://colorgrade.video/videos/log-footage-color-management-before-a-look#t=0) 2. [ Play from 0:13 The input transform ](https://colorgrade.video/videos/log-footage-color-management-before-a-look#t=13) 3. [ Play from 0:30 Export as a LUT ](https://colorgrade.video/videos/log-footage-color-management-before-a-look#t=30) 4. [ Play from 0:36 Try it yourself ](https://colorgrade.video/videos/log-footage-color-management-before-a-look#t=36) English captions [Watch page and full transcript ](https://colorgrade.video/videos/log-footage-color-management-before-a-look) ## Key takeaways * Log is a storage format, not a look: it spaces the stops evenly so a wide dynamic range fits in the file, and it must be converted for display. * Colour management has three stages: input transform, working space, output transform. In the studio they are **Footage**, your grade and **Output**. * A technical LUT converts (**Before the grade**, always at full strength); a creative LUT styles (**After the grade**, to taste). * A 3D LUT is a lattice of colour samples. It can hold any colour change, but never grain, windows, vignettes or anything that moves over time. ## In this chapter 1. [ 1. Why log footage looks flat ](#why-log-looks-flat) 2. [ 2. Colour management in plain words ](#colour-management) 3. [ 3. Setting up the Footage panel ](#footage-panel) 4. [ 4. What a 3D LUT really is ](#what-is-a-3d-lut) 5. [ 5. Technical LUTs and creative LUTs ](#technical-vs-creative-luts) 6. [ 6. HDR footage: HLG and PQ, honestly ](#hdr) 7. [ 7. Try it: convert log, then add a look ](#try-it) ## Why log footage looks flat A camera sensor responds to light linearly: twice the light gives twice the signal. Each stop of exposure is a doubling, so in a linear file the brightest stop takes half of all the code values and the darkest stops share a handful. That wastes precision on highlights, where the eye can’t see small differences, and starves the shadows, where it can. A log curve fixes this by recording the logarithm of the light, which gives each stop roughly the same number of code values. Twelve or more stops fit into a 10-bit file with room to grade. The price is that nothing is encoded for a screen. In Sony’s S-Log3, for example, 18% grey lands at about 41% on a waveform, a white card at only about 61%, and the darkest shadows never reach the bottom. The curve keeps climbing above white to hold several more stops of highlight. Shown as is, the picture has no real black and no real white: it looks flat. ### Gamut: why log also looks pale Most log profiles also record in a wide gamut such as S-Gamut3.Cine, V-Gamut or Cinema Gamut. A gamut is defined by three primaries, the purest red, green and blue the format can describe, plus a white point. Wide-gamut primaries lie well outside the ones a normal screen uses. Show that file without converting it and the screen reads the numbers as if they used its own primaries, so every colour appears less saturated than it was. Log is two problems at once, tone and gamut, which is why a proper conversion has to handle both. Shoot log in 10-bit wherever the camera offers it. With only 256 levels per channel, 8-bit log spreads too few values across each stop, and smooth gradients like skies band once the contrast is put back. ## Colour management in plain words Colour management means always knowing what the numbers in a file mean and converting them deliberately. Every managed pipeline has the same three stages: 1. **Input transform.** Undo the camera’s log curve to recover scene light, then convert its gamut into the working space with a 3×3 matrix. 2. **Working space.** Where you grade. Because every camera now speaks the same language, a grade behaves the same on a Sony clip and a Panasonic clip. 3. **Output transform.** Render the scene for a display, rolling off the highlights, and encode it for the delivery standard, usually Rec.709 for SDR video. DaVinci Resolve does this with a Color Space Transform effect or a colour-managed project; ACES is the same idea with an industry-standard working space. In the studio, the **Footage** panel is the input transform, your layers are the work in the working space, and the **Output** setting plus the highlight roll-off form the output transform. Footage that was never log, an ordinary phone clip for example, stays on **Standard video (Rec.709)** and passes through untouched. ### Rec.709 versus Rec.2020 Rec.709 is the standard for HD video: its primaries, white point and transfer curve are what ordinary screens, players and platforms expect. Rec.2020 is the standard for UHD and HDR, with primaries so pure that it covers roughly three quarters of the colours humans can see, against about a third for Rec.709\. Some log formats, such as **Apple Log / Rec.2020** and **N-Log / Rec.2020**, record in Rec.2020 primaries. Converting to Rec.709 has to squeeze those extra colours into the smaller gamut, so watch very saturated light sources, such as neon and LED signs, on the [**Vectorscope**](https://colorgrade.video/color-grading-tutorial/video-scopes) after converting. ### Choosing an output curve __Output options in the Footage panel__ | Output | What it is | Use it when | | ------------- | ----------------------------- | ---------------------------------------------------------- | | **Rec.709** | BT.709 camera curve (default) | Almost always: matches camera LUTs and what editors expect | | **Gamma 2.4** | Pure 2.4 display encoding | The next step expects display-referred 2.4 | | **sRGB** | The computer and web curve | Stills or graphics work in sRGB | The difference is visible: with **Gamma 2.4** or **sRGB**, mid-grey is encoded higher than with **Rec.709**, so the same grade looks lighter and softer in the shadows. Pick what the next step expects and grade with that choice made. **Highlights** offers **Soft roll-off**, which bends the top of the range smoothly as film does, or **Clip**, which keeps everything linear until it hits white. ## Setting up the Footage panel 1. In **Pro**, open **Footage** and choose the entry that matches both halves of the camera setting, curve and gamut. **S-Log3 / S-Gamut3.Cine** and **S-Log3 / S-Gamut3** are different conversions; picking the wrong half gives believable but wrong colour. 2. Trim **Log exposure** if you exposed away from the maker’s reference, as many people do with log. It works in stops before the conversion, so the curve stays correct. 3. Leave **Output** on **Rec.709** unless you know you need another. 4. Now grade. **Auto colour**, [white balance](https://colorgrade.video/color-grading-tutorial/white-balance) and looks all act on the converted picture. [ ![The Footage panel in Pro mode with S-Log3 / S-Gamut3.Cine selected as the input, Log exposure at 0, Output set to Rec.709 and Highlights set to Soft roll-off.](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/footage-panel-settings.webp) (enlarge image) ](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/footage-panel-settings.webp) The **Footage** panel: input transform, **Log exposure**, **Output** and the highlight roll-off. [ ![Split compare of an S-Log3 test chart in the studio: the left half is flat and grey, the right half converted to Rec.709 with full contrast, and the waveform beside it spreads from near 0% to near 100%.](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/slog3-before-after-waveform.webp) (enlarge image) ](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/slog3-before-after-waveform.webp) S-Log3 before and after **S-Log3 / S-Gamut3.Cine**: the waveform spreads to a full range. The conversions use the transfer functions and gamut matrices the camera makers publish. Where makers haven’t published them, the studio says so: **D-Log M (approximate)** is an approximation, and Apple Log 2, GoPro Log and Samsung Log are not built in. For those, import the maker’s own LUT with **Apply LUT** set to **Before the grade** and leave **Footage** on **Standard video (Rec.709)**. Never convert twice: a clip a phone app has already turned into Rec.709 is not log any more. ## What a 3D LUT really is A look-up table is a list of answers worked out in advance. A 1D LUT has a curve for each channel separately, so it can change contrast and per-channel balance but nothing that depends on the mix of channels. A 3D LUT samples the whole colour cube: for a grid of input colours it stores the output colour, and anything between grid points is interpolated. Because it maps each colour to any other colour, a 3D LUT can hold saturation changes, hue shifts, a log conversion or a complete look. __Common 3D LUT sizes__ | Size | Grid points | Typical use | | ---- | ----------- | ------------------------------------------- | | 17 | 4,913 | Gentle looks, small files | | 33 | 35,937 | The usual default for looks and conversions | | 65 | 274,625 | Steep conversions and fine detail | ### Tetrahedral versus trilinear Each colour falls inside a small cube of eight grid points. **Trilinear** blends all eight. **Tetrahedral** splits the cube into six tetrahedra and blends the four corners of the one the colour lies in. Tetrahedral is more accurate for the same grid, keeps neutral greys on the grey axis, and handles sharp hue changes more smoothly, so it is the default here; DaVinci Resolve and other applications offer both. Switch **Interpolation** to **Trilinear** only to match an application that uses it. ### What a LUT cannot hold A LUT sees one pixel at a time and knows nothing about its neighbours, its position or the time. So it cannot hold grain, sharpening, halation, bloom, a vignette, a window or qualifier that depends on position, or keyframes. It also only covers the input range it was built for: values above its top, such as log highlights fed into a LUT built for Rec.709, are clipped. That is why the studio’s **Export .cube** warns when the grade contains anything a LUT can’t carry. [ ![The Export dialog on the LUT (.cube) tab with LUT size options 17, 33 and 65, 33 selected, and the Export .cube button.](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/export-lut-size.webp) (enlarge image) ](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/export-lut-size.webp) Exporting a grade as a .cube: **LUT size** sets the grid; 33 suits most looks. ## Technical LUTs and creative LUTs Both are .cube files, and that causes most LUT mistakes. They do different jobs at different points in the chain: __Technical versus creative LUTs__ | | Technical (conversion) LUT | Creative (look) LUT | | | ---------------------------- | --------------------------- | ---------------------------- | | Job | Convert log to Rec.709 | Add a style | | Expects | One specific camera profile | Corrected Rec.709 footage | | **Apply LUT** | **Before the grade** | **After the grade** | | **LUT intensity** | Always 100% | To taste, often 40-80% | | Examples | Maker’s log-to-709 LUT | Film, teal and orange, moody | The order is conversion, then correction, then look. A creative LUT applied to raw log gets the wrong input and looks muddy; a conversion LUT applied after you have already balanced the footage converts something that is no longer log. **LUT intensity** below 100% on a conversion LUT doesn’t give a softer conversion; it gives a mixture of right and wrong colours. On a creative LUT it is the most useful control there is, and the next chapter, [building a creative look](https://colorgrade.video/color-grading-tutorial/creative-looks), shows what to put in one. [ ![The LUT section of the Creative panel showing Import LUT, LUT intensity, Interpolation set to Tetrahedral and Apply LUT with the choices After the grade and Before the grade.](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/creative-panel-lut.webp) (enlarge image) ](https://colorgrade.video/guides/color-grading-tutorial/log-footage-and-luts/creative-panel-lut.webp) LUT controls in **Creative**: **Apply LUT** decides whether the LUT converts or styles. Try it in the studio Import a look LUT in **Creative**, set **Apply LUT** to **After the grade**, then lower **LUT intensity** while watching the **Vectorscope**: the trace shrinks back towards the corrected picture. More detail is on [applying a LUT to video](https://colorgrade.video/apply-lut-to-video). ## HDR footage: HLG and PQ, honestly HDR video is not log, but it raises similar questions. HLG (hybrid log-gamma) uses a curve that looks roughly normal on an SDR screen in its lower part and log-like above it; many phones record it by default. PQ, used by HDR10, describes absolute light levels up to 10,000 nits. Both use Rec.2020 primaries, together defined as Rec.2100. The studio grades and exports SDR. **HLG (Rec.2100)** and **PQ / HDR10 (Rec.2100)** in **Footage** tone-map HDR down to SDR with a simple curve, and the panel labels them as approximations. There is a further catch: browsers often convert tagged HDR video to SDR before the studio ever sees it. If you choose **HLG (Rec.2100)** for a phone clip and the picture looks wrong, usually too contrasty, the browser had probably converted it already; set **Footage** back to **Standard video (Rec.709)**. For an HDR master, use an application built for HDR delivery. ## Try it: convert log, then add a look Convert a log clip with the Footage panel, trim it in stops, then add a creative look after the conversion and check both on the scopes. 1. 1 ### Open the log clip in Pro Open the clip, switch to **Pro** and show the **Waveform** and **Vectorscope**. The waveform sits in a narrow band and the vectorscope trace is small. 2. 2 ### Set the input transform Open **Footage** and choose the profile you shot in, for example **S-Log3 / S-Gamut3.Cine**. The waveform spreads out and the colours fill out. 3. 3 ### Trim in stops Adjust **Log exposure** until mid-tones land where you want them. Leave **Output** on **Rec.709**. 4. 4 ### Add the look after the conversion Pick a look in **Looks**, or import a creative LUT in **Creative** with **Apply LUT** on **After the grade**, and set its strength. 5. 5 ### Export the look as a LUT Open **Export**, choose **LUT (.cube)**, set **LUT size** to 33 and choose **Export .cube** to use it in another editor. ## Log footage and LUTs: questions ### What is the difference between log footage and Rec.709? Log is a recording format that spaces the stops evenly to keep as much range as possible, usually in a wide gamut. Rec.709 is the display standard for HD video. Log has to be converted to Rec.709 to look normal on an ordinary screen. ### Should I use a LUT or a colour space transform for log footage? Either works if it matches the camera profile. A colour space transform, like the **Footage** panel, keeps highlight values beyond white for the roll-off, while a conversion LUT is fixed and clips anything outside its range. Use the maker’s LUT where no built-in transform exists. ### What do 17, 33 and 65 point LUTs mean? The number of grid points along each axis of the 3D LUT: 17 points is 4,913 samples, 33 is 35,937 and 65 is 274,625\. More points follow steep or complicated colour changes more closely, at the cost of a larger file. ### Tetrahedral or trilinear interpolation: which is better? Tetrahedral, in almost every case. It uses four surrounding grid points instead of eight, keeps greys neutral and follows hue changes more accurately. Use trilinear only to match another application that uses it. ### Can a LUT include film grain or a vignette? No. A LUT maps each colour to another colour, one pixel at a time, so it cannot add texture, position-based effects such as a vignette or window, or changes over time. Add those in the editor where you apply the LUT. ### Can I grade HLG or HDR10 video here? You can grade it, but the studio outputs SDR. The **HLG (Rec.2100)** and **PQ / HDR10 (Rec.2100)** inputs use a simple tone map, and browsers often convert HDR to SDR before the studio sees it, so check the waveform and choose the input that looks right. [ ← Previous: chapter 7 Skin tones ](https://colorgrade.video/color-grading-tutorial/skin-tones) [ Next: chapter 9 → Creative looks ](https://colorgrade.video/color-grading-tutorial/creative-looks) ## Keep going * [ Convert log footage to Rec.709 Camera log profiles converted to normal video, with the maker LUT route for the rest. ](https://colorgrade.video/log-to-rec709) * [ Apply a LUT to a video online Load a .cube or .3dl file, choose where it sits in the grade, and export. ](https://colorgrade.video/apply-lut-to-video) * [ Creative looks Build a look on top of a correction: complementary colour, film-style contrast and texture, split toning, black and white, and the restraint that holds it together. ](https://colorgrade.video/color-grading-tutorial/creative-looks) * [ Contrast and tonal range Set black and white points, place mid grey, and shape contrast without clipping either end, using the waveform and false colour. ](https://colorgrade.video/color-grading-tutorial/contrast-and-tonal-range) * [ Convert Apple Log to Rec.709 iPhone log clips turned into normal video in the browser, even on the phone itself. ](https://colorgrade.video/apple-log-to-rec709) All 13 chapters 1. [ 1\. Video scopes ](https://colorgrade.video/color-grading-tutorial/video-scopes) · Basics 2. [ 2\. Contrast and tonal range ](https://colorgrade.video/color-grading-tutorial/contrast-and-tonal-range) · Basics 3. [ 3\. White balance ](https://colorgrade.video/color-grading-tutorial/white-balance) · Basics 4. [ 4\. Colour wheels ](https://colorgrade.video/color-grading-tutorial/color-wheels) · Intermediate 5. [ 5\. Curves ](https://colorgrade.video/color-grading-tutorial/curves) · Intermediate 6. [ 6\. Secondary correction ](https://colorgrade.video/color-grading-tutorial/secondary-color-correction) · Intermediate 7. [ 7\. Skin tones ](https://colorgrade.video/color-grading-tutorial/skin-tones) · Intermediate 8. [ 8\. Log footage and LUTs ](https://colorgrade.video/color-grading-tutorial/log-footage-and-luts) · Advanced 9. [ 9\. Creative looks ](https://colorgrade.video/color-grading-tutorial/creative-looks) · Advanced 10. [ 10\. Shot matching ](https://colorgrade.video/color-grading-tutorial/shot-matching) · Advanced 11. [ 11\. Delivery and export ](https://colorgrade.video/color-grading-tutorial/delivery) · Advanced 12. [ 12\. Grading workflow ](https://colorgrade.video/color-grading-tutorial/workflow) · Intermediate 13. [ 13\. Common mistakes ](https://colorgrade.video/color-grading-tutorial/mistakes) · Basics