But, for the sake of this guide, we will assume the display in question has good internal manual CMS controls, and provide a step-by-step overview to the 'best-practice' approach for manual display calibration.
With this acceptance, there are six major calibration steps to be taken:
Black & White levels
Best 'Picture Mode'
Grey Scale/White Balance
While the above list is fairly simple, it will be necessary to re-visit most entries for a second, or even third time, after checking the other entries. For example, the Black & White levels will need to be re-verified after the best Picture Mode' has been found - but you really need to set the black and white levels before evaluating the display's different Picture Modes, as incorrect black & white levels will make a Picture Modes look wrong...
It is imperative to understand that such a 'repetitive' and 'circular' approach to manual calibration is a requirement due to to the way just about all manual TV calibration controls work.
Manual Display Controls
The actual controls that will be used during manual display calibration will vary depending on what is provided by the specific display being calibrated. Knowing what controls are available, and what they are used for is a critical step in gaining accurate final calibration.
It is also important to note that many displays have very poor controls, to the point that some controls do not work as expected (including wrong control labeling, incorrect functionality, and just plain poor design!). It really is key to know if the display in question has controls that operate as expected, or not.
Picture Mode selects different display-wide settings, on-top of which the other display controls work (often with different controls active or not, depending on the Picture Mode selected). For accurate display calibration the need is to find the mode that is the least inaccurate. This is usually 'Movie' or 'Cinema' mode, which contrary to their names is actually closer to a the correct colour and gamma calibration for TV's, and has nothing to do with trying to emulate Cinema imagery. Additionally, when selecting these modes many home TVs provide additional manual controls, as described below. If a User Mode is available, that is often the best to select, as it provides the best 'blank canvas' with which to work, with the best selection of additional manual controls.
Colour Profile options (or Picture Options, or similar names) on some displays are usually a sub-set of Picture Mode, and provides yet another level of 'options'. As with Picture Mode, the best setting to chose is often 'User' or 'Custom'. But, it is always best to verify each mode with direct profiling.
Backlight, where available (usually on LCD displays, not Plasmas or OLED) controls the overall illumination level used for the screen, and can be used to set the overall 'brightness' of the screen. The control will affect both peak white and minimum black, with more effect on white. Unlike Brightness and Contrast controls there is little chance of 'clipping'. The primary function of the Backlight control is to enable Peak White to be set, in conjunction with the Contrast control.
projectors often have an Iris control (and possible bulb power) which is equivalent to 'Backlight' on an LCD display, and should be used in a similar way.
A second function of Backlight is to move between 'Night' and 'Daylight' settings, if you cannot accurately control the viewing environment (limit daylight contamination). Changing the Backlight setting can usually be performed without (badly) affecting other settings.
Brightness controls the point at which black detail on the screen becomes clipped or crushed if set low, or if set too high will cause blacks to look grey and washed-out.
Contrast controls the point at which white detail on the screen clips or crushes if set too high, and will make whites appear dim, grey and washed-out if set too low. Contrast needs to be set in conjunction with Backlight where available, and on displays without a Backlight is used to set the peak white value directly.
While Sharpness has no direct effect on calibration, it does have a perceived effect if set incorrectly. Usually, incorrect means set to a too high value, causing 'ringing' artefacts around image edge transitions.
Colour usually controls the colour saturation within the display's fixed gamut. That means it will increase the saturation colours that are within the display's gamut, but will have little or even no effect on colours at the gamut edge. Colour should be set to maintain internal gamut colour saturation accuracy, and not to try to extend the display's maximum gamut.
Tint is often a very simple colour ratio balance, usually altering the ratio of green to red, making one colour more prevalent compared to the other. With most modern displays this should be left at 'null'.
Hue can be present as an alternative to Tint, and changes the overall screen colour based on a vector rotation. As with Tint, this should be left null if better CMS controls are available. On some displays the 'Hue' control is just a 'Tint' control, again just altering the ratio of green to red.
Tone, or Colour Temperature, is usually a simple set of presets ranging from Cool, to Warm 1, and Warm 2. The correct setting is the one that sets the white point colour temperature closest to the desired standard. Warm 2 is usually closest.
Gamma controls are often a simple selection of presets, meaning the closest value to the desired target should be used, or a slider with relative values. The offered presets are often not the same as the suggested value they are labeled with, so the result must be profiled (measured) for verification.
Many displays, especially those that are selected by users looking for decent image display capabilities, have additional 'Advanced Settings'. Theses controls usually include more accurate CMS (Colour Management System) capabilities, but may also included some of the controls listed above.
White Balance sets the grey scale neutrality (colour temperature), often via 2 point or 10 point controls, depending on the display. 2 point allows for the colour temperature to be set individually for low brightness levels and higher ones. 10 point provides for control in 10% steps throughout the brightness range.
With multiple point White Balance you can often use the controls as 'fine' adjustments for Gamma, as changing the RGB values for each 'point' by the same amount, positive or negative, will change the relative luminance of the selected point, so altering gamma at that point.
RGB Bias & Gain
On many displays White Balance is controlled by settings called RGB Bias, Offset, Cuts, or similar for the low-end, and RGB Gain, Drive, or similar for highlight control. Such controls work as for 2 Point White Balance.
Some displays - very few - offer an advanced Multi-Point Gamma control, which can be used to finely tune the overall gamma response of the display.
Colour Space provides control of the display's gamut, within the limits of the screen's capabilities. The only option we are interested in is 'Custom', as this allows the user to set the colour space as accurately as possible to the desired colour space standard. This is often via controls for RGB primary as well CMY secondary colours.
Having secondary CMY controls goes against standard display calibration colour science, as secondary CMY colours should be a simple and direct calculation from the primary colours, and shows the poor colour management inherent in most home TVs.
Most home TVs also have a plethora of additional modes/controls that must be disabled for accurate display calibration. Such modes include:
Advanced Contrast Enhancement
Auto Light Limiter
And many, many more...
Such modes, if active, will defeat any and all attempts at accurate display calibration.
The tools required for Manual Display Calibration are basically the same as for 3D LUT calibration, as the initial steps are essentially the same.
The free LightSpace DPS version of LightSpace CMS can be used for all the manual display calibration steps outlined within this guide.
A probe is required to measure values from the display, enabling the correct manual settings to be made. The cheapest probe we recommend is the i1 Display Pro OEM RevB, especially when you consider the actual level of accuracy possible with Manual Display Calibration.
Patch Generation is required to enable known stimulus colours to be sent to the display being calibrated, enabling the probe to take readings and allow LightSpace DPS to compare the measured values with the actual target vales for the required colour space. For most calibration work the HDMI output from the LightSpace CMS laptop is perfect from this, as it enables Closed-Loop (the probe and patch generator are both under LightSpace CMS control) measurements. More information can be read on the Direct HDMI for Display Profiling page.
If it is desired to use an external Patch Generator, and a purchased license for LightSpace CMS is being used, LightSpace CMS is compatible with many different systems, from the IS-Mini, to Resolve, Scratch, and Mistika, as well as the Lumagen and Prisma LUT Boxes, DVDO Test Patch Generator, and madVR HTPC system, plus many others. See the Tips & Tricks pages for more info.
Calibration Test Patterns
Test Patterns are used for two distinct applications. The primary use is to enable the manual setting of display controls, for black and white levels for example. The second application is to enable controls that are not directly colour related to be set - such as 'Sharpness'.
Calibration Discs can be used as an alternative to patch generator, specifically with the DIP mode (Display Independent Profiling)capability of LightSpace CMS, which enables the calibration disc to automatically play the correct colour patches as required for LightSpace CMS profiling, as well as providing a plethora of alternative Test Pattern images. We recommend the use of Ted's LightSpace CMS Calibration Disc.
Initial Display Setup
With the required tools at the ready it's time to start the Display Calibration process. This guide will focus on the basic requirements, but any competent individual will quickly understand that there are additional possibilities that can be utilised to enhance the whole calibration procedure. There are additional User Guides that can be reviewed to advance user knowledge.
Before embarking on any calibration workflow it is a good procedure to first profile the display to assess its present calibration status. With LightSpace CMS this is simple to perform using the system's Quick Profiling capabilities, and will help define the areas of manual display control that need particular focus.
- Start LightSpace CMS, navigate to 'Tools/Discoverable Probes' and select the correct probe.
- Connect the probe.
- Allow 20 to 30 minutes probe warm-up time.
- Start the display, and again leave for 20 to 30 minutes warm-up time.
(To shorten warm-up times it is possible to run dummy profile sequences.)
- Open the 'Calibration Interface' window, and follow any on-screen instruction for probe calibration, if needed.
- Select 'Probe Options' and set the required parameters for the probe and display combination.
(Review the Profiling User Manual for more information on Probe Options.)
- Using Extended Desktop enables LightSpace CMS to run on the laptop screen, and the Patch Sequence run on the display to be calibrated.
(It's a good idea to also set the laptop Desktop Background to black.)
- Double click the small 'Patch Window' to open the free-floating patch window, and drag to the Extended Desktop, which is the display to be calibrated.
(A double click on the free-floating patch window will remove the window border.)
- Set the patch windows to the desired size, and place the probe as required to read the patch location.
(Patch size and probe location - contact or non-contact - depends on the display technology being profiled, usually contact for LCDs, non-contact for displays that heat up substantially, such as Plasmas and OLEDs, and also non-contact for projectors. Set 'Extra Delay Time' if the display requires 'settling' time between patch changes - Plasmas for example.)
- Set the Target Min & Max Luminance values for the display using the 'Options' menu - either manually or automatically via the Update button - and select the target Colour Space from the drop-down menu on the main Calibration Interface window.
(The Min & Max Y values do not 'need' to be set at this point - as they can be changed at any time - but they set the Target Values, and are the basis for the reported Y accuracy during measurements, and so will affect the reported Delta-E values when performing Manual Measurements.)
(For initial profiling these should be set manually to the ideal values for the display to be profiled - such as 0.05 Nits Min, and 100 Nits Max, as is defined ideal for a Grade-1 professional display.)