Truelight Version 2.1 Shake Node Fil m Light DIGITAL FILM TECHNOLOGY Truelight Product Version: 2.1 Shake Node Document Version: 1.2 Date: 17/03/2005 Modified: 14/04/2005 21:03 © FilmLight 2005 Truelight Truelight Overview Shake Node 1 Truelight Overview Truelight is a complete film colour management system for pre-visualising film images on electronic display devices. It provides a full simulation of the entire workflow from digital data to final projected image. By carefully measuring and characterising each stage in the workflow, the closest possible match between preview on the Shake monitor and the final projected film image can be achieved. The simplified overview diagram below shows how the Truelight system uses calibration data to create a 3D colour-cube transform, accurately matching the electronic display of digital film images to the projection of a print created from the same digital source: NEG FILM STOCK PRINT FILM STOCK FILM RECORDER FILM PROJECTOR CAL CAL CAL CAL COMBINED C A L I B R AT I O N CAL D I G I TA L F I L M I M AG E S HD MONITOR OR D I G I TA L P R O J E C T O R S HA K E TRUELIGHT TRANSFORM (PLUGIN) CAL UI MONITOR For more details on Truelight, please visit the FilmLight web pages at www.filmlight.ltd.uk, and follow the product link to the Truelight sections. Truelight 2 Truelight Licence Shake Node Truelight Licence Truelight is automatically licensed to use generic profiles. The Truelight node can be upgraded to load custom profiles if required. For further information, please refer to the Truelight support section of the FilmLight website: www.filmlight.ltd.uk/support/truelight.html Truelight Monitor Calibration Shake Node 3 Monitor Calibration A monitor must be correctly calibrated before it can accurately reproduce images. The Truelight node provides a built in tool for the visual calibration of the Shake monitor. It is also possible to use monitor calibration files which have been created using a Truelight Monitor Probe and imported into the machine. Before calibrating the Shake monitor, it should be set up to ensure optimal performance in your current viewing environment. You should use the controls on the display to set the brightness, the contrast, and the white point. The FilmLight recommended practice document RP-FL001 "Viewing Environment and Monitor Setup" gives more detailed advice on setting up your viewing environment - this can be downloaded from the FilmLight website. The following procedure applies to the visual calibration of the Shake user interface monitor. If you have an external HD broadcast monitor, Truelight provides two preset calibration options which may be appropriate for your monitor (see step 5 on page 8). Before starting, ensure that the VLUT and user scripts are switched off: To start the Truelight Monitor Calibration utility: 1 2 Click on the `other' tool tab This tab should include two Truelight icons - click on the Truelight Calibrate icon: A `TLCalibrate' node will appear in the Node View. This node does not require any inputs or outputs as it is just being used to generate a series of lineup patterns in the viewer: Truelight 4 Monitor Calibration Shake Node 3 The viewer should currently be displaying two patches side-by-side, a mid grey patch on the left and a patch composed of alternate white and black lines on the right. Select the Parameters1 tab to access the Truelight monitor calibration controls: Before adjusting any of the controls, check that the `useProxy' setting in the `Globals' parameter tab is set to `Base', and the viewer is set to a 1:1 zoom. If necessary, click on the viewer Home button 4 to reset the viewer. Leave the gang button turned on so that all three sliders move together and then drag any of the rgb sliders to the left or right, to visually match the `brightness' of the two halves of the screen. It may help to view the screen through half-closed eyes so that the white/black lines on the right-hand side of the viewer appear to merge into a continuous grey patch. 5 If there is any noticeable colour cast on the left side of the screen compared to the right, click on the gang button to turn it off and then trim the rgb sliders independently to match the colour of the two patches. 6 Once the two halves of the viewer match, and there appears to be a single uniform grey patch across the whole monitor, click on the `Next' step button Two new patches appear at half the level of the previous ones (i.e. one stop less), and the step number shown above the rgb sliders increments. Truelight Monitor Calibration Shake Node 5 7 8 Repeat the process of matching the two halves of the screen as described above and again, click on the `Next' step button Repeat the process a further eight times to match all ten sets of grey patches. If the patches are too dark to see any differences, just click on the `Next' step button Note that it is possible to step back to a previous grey level at any time by clicking on the `Prev' step button Once all the patches have been matched, the monitor calibration data must be saved: 9 Click on the template button to choose a calibration template appropriate to the type of monitor you have (currently, Apple Cinema and CRT displays are supported). The template list will also include any existing monitor calibration files, including ones created using a Truelight Monitor Probe. You can use a previous calibration as a template. The new calibration will have new RGB tone curves, but the other display properties are inherited from the template file. 10 Type a file name for this monitor calibration data in the calName box, and then click on the `Save' button (note that the default name for this file is `monitor'). Note that if the chosen calibration file already exists, a warning message will appear asking whether you want to overwrite it. Cancel if you do not. The calName box has a browser control. You can put calibrations in other directories, but the default directory is where Truelight will expect to find them. The monitor has now been calibrated for use with Truelight and the `TLCalibrate' node can be deleted. Warning: If you alter the display controls now, your new calibration will be invalid. Please lock or disable any controls on your monitor, if you can. Note that the calibration tool only calibrates the tone curves. It cannot measure the absolute brightness or colour of your monitor. The standard Apple Cinema and CRT templates use the Truelight default white point (16 foot-lamberts D65). If you are using a Truelight Monitor Probe calbration as your template, then you will get the correct absolute white point for your monitor. For more details see Truelight note FL-TN-00-001 on the FilmLight website. Truelight 6 Monitor Calibration Shake Node Calibrations based on the standard Apple Cinema and CRT templates link display RGB values to absolute colours in CIE XYZ. Truelight also supports display calibrations that link display RGB values to colours relative to the display white in CIE L*a*b*. For more details on these standard colour spaces see Truelight note FL-TN-00-002 on the FilmLight website. Truelight The Truelight Viewer Shake Node 7 The Truelight Viewer Once the Shake monitor has been calibrated (see Monitor Calibration on page 3), a Truelight node can be added to provide an accurate preview of what the final film print will look like: 1 2 Select the color tool tab. Click on the Truelight Viewer icon: A Truelight node will appear in the Node View. Insert the Truelight node into the tree at the appropriate point. 3 Click or double-click on the Truelight node to load its parameters: 4 Click on the profile button and select a Truelight profile from the pop-up list which matches the film-out process (print stock) you are simulating. Truelight 8 The Truelight Viewer Shake Node The default profile set is based on different film stocks, projected with a standard xenon lamp. Advanced users can make their own profiles using a text editor (for more details see Truelight note FL-TN-00-003 on the FilmLight website). If you require detailed simulation of your light box, projector, or specific film-out process, please contact FilmLight for information on alternative profiles and customised calibrations. 5 Click on the display button to choose the monitor calibration file for your display. If you have not yet calibrated the Shake monitor, please use the Truelight Calibration utility (see page 3). The list of display calibrations will include three standard files - rec709, rec709legal, and SonyHD. These calibrations are normally used in conjunction with an external broadcast monitor. The two rec709 calibrations match the standard ITU broadcast formulae; SonyHD matches a typical well-set up HD monitor. 6 Finally, click on the colourSpace button to set the correct working colour space for your material. The options are `log', `linear' and `video'. These settings correspond to the basic colour space settings in the Shake LogLin node, but without the additional parameters (see Appendix for more details). The Truelight node should now be set up to correctly simulate the chosen film-out process on the calibrated Shake monitor. Note that the screen shot on the previous page shows controls for white point luminance (`whiteLuma') and chrominance (`whiteChroma') at the bottom of the `advanced' drop-down section. These controls are only shown if the currently selected display needs them. If you cannot see these three sliders, then you may be using a CIE L*a*b* display calibration. Note also that there are three printerPoint controls. These controls are only shown if the currently selected profile can use them. If you cannot see the three `printerPoint' sliders, then you may be using a profile that matches your display to another display. In this case, the profile is not simulating a film-out process, so these controls would have no function. Truelight The Truelight Viewer Shake Node 9 Viewing controls When viewing a Truelight node, the images displayed should be an accurate representation of what you would see if the image data were recorded and printed to film, then projected on the cinema screen. Ideally there should be no need to adjust anything. However, sometimes the user needs to adjust the display to compensate for `external' factors not modelled within the Truelight profile. Note: It is very important that the user does not adjust any of the controls on the monitor itself once it has been calibrated. If the monitor controls are adjusted, the monitor will have to be recalibrated (see page 3). The Parameters1 tab contains the following controls to allow for adjustments to the simulation of printer points and also to enable other Truelight modes: printerPointR,G,B - These controls allow offsets to be applied to the Truelight simulation of printer lights at the printing stage of the film-out process. Adjust them to match a print which has come out with a colour cast. The default setting is zero. These sliders may be hidden if, for example, the currently selected profile does not simulate a film-out process. showOutOfGamut invert - Click on this toggle button to turn on Truelight's gamut alarm (see page 11). When active, any out-of-gamut' colours are highlighted. - Click on this toggle button to invert the operation of the Truelight node. An inverted node will turn display RGB into film data. Truelight 10 The Truelight Viewer Shake Node oneDLUT - Click on this toggle button to replace the Truelight cube transform with simple look-up tables. This is slightly faster, but it is only accurate for neutral tones. When this control is enabled the 'showOutofGamut' control is hidden as it will have no effect. Expanding the `advanced' section at the bottom of the panel provides access to additional controls to compensate for ambient lighting conditions. Adjustments can also be made to the white point (luminance and colour temperature) of the display: brightness - The brightness level of the displayed image can be shifted up or down. If you are working under office lighting, you may want to turn up the brightness. flare - When ambient light levels are high, detail in the darker areas of an image can become difficult to see. Flare correction can be applied to effectively `stretch' the black end of the gamma curve. This is useful when it is impractical to black out the room. The default value of 0.01 matches the reference cinema conditions. whiteLuma - Sets the maximum white output level of the monitor. The default setting is appropriate for matching cinema conditions. This control is hidden if the current display calibration does not use it. whiteChromaU,V - These two sliders adjust the overall colour balance of the monitor. Changing the `u' value shifts the white point towards red or green. Changing `v' shifts white towards yellow or blue. The default settings shown match D65, the white used ...