ColourSpace uses a Sub-Range approach to patch scaling, which means it will define the output patch triplet values based on the patch scale range set within the Settings menu.
Resolution sets the Bit Depth used to define patch values and sent to external TPGs, depending on their capabilities.
Patch Scale & Resolution Settings
The Patch Scale options set the range between which the patch triplet values, sent to any attached Test Patch Generator, will be restricted to, and needs to match the display's setting for input signal range. This is usually Full for PC displays, and Legal for TVs, with Extended specified for 109% super white, as sometimes used in post-production workflows.
Setting this value incorrectly, or more importantly setting the value incorrectly within the attached TPG will cause errors with mismatched patch values resulting in incorrect Calibration. Specifically, setting the TPG correctly, be that a stand alone TPG, a TPG built into a LUT box or video processor, or a display's in-built TPG, is a critical setting to understand and set correctly.
The Resolution options set the bit depth used to define the patch colour within ColourSpace, which may or may not also define the bit depth used by any external patch generator, be that a stand alone TPG, a TPG built into a LUT box or video processor, or a display's in-built TPG.
With any TPG that is ColourSpace Integrated, be that stand alone or integrated into a display or LUT box, etc., ColourSpace will send patch triplet values in the correct bit depth required by the TPG, based on the Resolution value setting. Setting the Resolution value within ColourSpace to match that of the TPG's expected input triplet bit depth is therefore the expected configuration.
What this value should be is not always obvious, and can take understanding for the TPG in use.
See the TPG Operation page of the website for more information
Manual Measure Sliders
The range the manual Measure Sliders work to is defined by the Patch Scale values set within Settings, and will limit the sliders to just the set range. If Legal is set as the Patch Scale values, the sliders will not go beyond those values. For example, setting Limited range (8-bit) will prevent the sliders from going below 16, or above 235.
The displayed patch bit depth is defined by the selected Resolution value. When changing Resolution bit depth, the patch values are absolute, so if a 235 (8-bit) patch is displayed, and the Resolution is changed to 10-bit, the patch displayed will remain as 235, but now as a 10-bit patch colour, so will be considerably darker.
Resolution bit depth should be set to match the display's bit depth, and that of the TPG being used. Setting to higher values will not increase calibration accuracy, and may cause less accuracy due to a miss-match between the value defined within ColourSpace, and the actual patch value displayed and measured on the display screen.
See TPG Operation for additional information.
Characterisation Presets
The presets held within the Characterisation menu, including Cube based and Quick Profiles, are automatically set to the range defined by the Patch Scale values set within Settings.
Patch Resolution is defined in floating point within ColourSpace, so the selected Resolution bit depth is irrelevant when performing Characterisation profiling, other than matching the signal expected by the TPG and display, as required.
User Preset Patch Lists
User generated .csv Patch Lists should match the Patch Scale setting defined within the ColourSpace Settings menu - Legal, Extended, or Full, as well as define the patch triplet values in the correct Resolution bit depth, to guarantee expected profiling results, although if there is a mismatch ColourSpace will rescale the patches as accurately as is possible, as the imported integer .csv patch list will have been converted into ColourSpace's internal float values.
The patch data displayed below the Patch Colour box will shows the triplet value in the ColourSpace set bit depth, while hovering over the drop-down Preset selector will display the Preset name, plus the range and bit depth of the .csv file in square brackets. Hovering over the any patches within the visual patch list will show the patch triplet value in the ColourSpace defined Resolution, the associated patch name from the .csv file in standard brackets, as well as the active bit depth in square brackets.
When performing an Auto Advance sequence, the highlighted patch being measured will start and stop with the min/max patches that match the set Patch Scale, not the min/max patches within the patch list, if they go below/above the values set via Patch Scale.
The Resolution bit depth set within ColourSpace should also be matched by the .csv triplet values, as the patch values are absolute.
The first numerical column defines a patch number, and can be in any order, with the following three columns defining the R, G, & B patch values, with the 5th, optional column, defining a name for the patch.
The Customer Downloads contains examples of .csv various Patch Sequences.
109% Extended Range
The concept of calibrating a display to 109%, extended range, to allow for super white, is not something that should be required for home TV calibration, as no broadcast material exceeds Legal range.
However, for post-production, 109% Extended Range is a valid concept, and needs to be understood with respect to Patch Scale.
When calibrating to 109% Extended Range, patch 235 (8-bit) should target 100 nits (for a Rec709 grading display), with patch 255 (8-bit) being 9% over-range. The luma value for patch 255 (8-bit) will vary depending on the target colour space EOTF, as well as the display's black level.
With ColourSpace, when working with 109% Extended range, the 100% patch (235 - 8-bit) is the target Peak White value.
ColourSpace always works 0% - 100% range, with 109% being over-range
The 1D graphs will plot the 0-100% range, with 109% plotted over-range.
To see over-range data, the graphs will need to be zoomed-out.
Limit Range
Limit Range limits the patch range such that the defined code value becomes the peak of the measured range, within the selected Patch Scale range, and is intended predominantly for absolute calibration, such as PQ based HDR.
If using Manual Measure, the sliders will be restricted to the set maximum value.
If a user defined Preset patch list is used, any patches over the set Limit Range value will be clipped, both in Manual Measure, and Characterisation.
When using ColourSpace's in-built patch sets within Characterisation, the whole patch range is re-scaled to fit within the defined Limit Range value.
Regardless of the method used to display the patches, the saved profile will plot the measured range within the defined Patch Scale, with the 1D graphs, such as EOTF, showing just measured range.
The above graphs show a pre-calibrated PQ ST2084 display, with a max peak luma of 1000 nits. After profiling with a Limit Range value of 769 (10-bit), the first graph shows the profiled 1000 nits range plotted within the full PQ ST2084 10,000 nits, while the second graph shows the same profile plotted against a PQ ST2084 colour space set to 1000 nits peak.
Critically, the Limited Range profile can be used to generate a calibration LUT, making it possible to profile a PQ based HDR display, with a burnt-in PQ EOTF active, and generate a more accurate calibration. No requirement to be forced to disable the PQ EOTF and replace with a pure power law EOTF.
For more information, see the PQ based HDR page.
Test Patterns
The in-built Test Patterns also follow the Patch Scale settings, with their signal range set to match the Patch Scale values. It is therefore important the correct Patch Scale values are defined, to match the display's input signal requirements, when using the Brightness and Contrast Test Patterns to set black and white clipping points, etc.
With Patch Scale set to Legal, the Brightness Test Patch is lifted, such that zero black becomes 16 (8-bit), and the Contrast Test Pattern is lowered, such that 100% white becomes 235 (8-bit).
With the correct Patch Scale settings, the Brightness and Contrast Test Patterns will look identical on Full Range, and Legal Range displays, enabling correct configuration.
Point Info Dialogue
The Point Info pop-up dialogue window is also constrained by the Patch Scale value settings, as the actual data in the profile is floating point, so normalised between 0-1.
Therefore, to see the actual point info as originally saved into the profile, the Patch Scale settings must be as set when the profile was made.
If the Patch Scale values are set differently, the point info triplet data will be re-scaled to match the selected range, maintaining the actual measured data relationship for graphing. This can, and will, result in invalid point data.
The Resolution bit depth also constrains the data displayed in the Point Info dialogue, and should ideally use the same Resolution value as used when the profile was generated, to see the point info as originally saved into the profile.
The above shows a 10-bit, 1 LSB step, profile, displayed with Resolution set alternatively to to 8-bit, and 10-bit. When set to 8-bit, blocks of 4 input patches all map to the same output patch number, as is expected.
