For many graphics systems, such as Photoshop, LUTs are not a colour management option. SpaceMan will convert 3D LUTs into ICC profiles for use in such systems, for Look Management as well as Display Calibration.
ICC Tools will be added to ColourSpace some time in the future
Presently stand alone SpaceMan software and license is provided
Initial Operation
To convert a 3D LUT into an ICC Profile, first start a new ICC profile using the New Profile button, or via File/New Profile menu. This will build a basic ICC Profile starting point, with the minimum Header and Tag data.
Note: You can also load an existing ICC profile into SpaceMan (v2 or v4) to enable it to be edited. Load an existing ICC profile either via the Open Profile button, or via File/New Profile, or by dragging and dropping an existing ICC profile directly on-top of the main SpaceMan window.
The above image shows a new starting ICC Profile with the Illuminant data shown - any Header or Tag information can be seen and edited by double clicking on the relevant information line.
With an ICC Profile active within SpaceMan a 3D LUT can be selected and added to the profile via the Import 3D LUT button. Select the 3D LUT format from the File Format drop down list, activating the Clip out of range values if required.
The required Class of Profile can also be set, as well as the option to Build VCGT Tag for use within a graphics card for direct 1D LUT based grey scale display management.
Note: For normal use within the likes of Photoshop for Look Management via the generation of an ICC profile that matches an original 3D LUT, the Input+BToA Tag option is the standard one to use. For display calibration the Display option is the correct one to use.
(Input profiles actually only require an BToA Tag, but some graphics systems struggle with such profiles, hence the Input+BToA Tag option.)
The RGB Space option should be used to match the expected colour space within the graphics program to be used. The most common selection will be sRGB, with Encoding, as for most graphics programs, such as Photoshop, this will be expected colour space.
Note, the use of Encoding Gamma for image manipulation is not correct, but as this is how such graphics programs work with ICC profiles it is a necessary evil for SpaceMan.
The Load Cube button can then be used to select the specific 3D LUT to load, via a folder navigation window.
Note: If the LUT to be loaded does not appear in the File Format list it may be possible to load the LUT by selecting a similar format LUT type from the File Format list, allowing SpaceMan to parse the unknown LUT data correctly. For example, to load a Resolve .cube 3D LUT use the 'Iridas' LUT option, as that is the same format.
When a LUT has been loaded the 3D LUT can be seen visually within the cube display.
The View Gamma button can be used to show a 1D RGB gamma profile of the 3D LUT, which is also the data that will be used within the VCTG Tag, if that option has been selected.
Selecting the Apply Cube button will add the 3D LUT to the ICC Profile, be that a new ICC profile, or an existing one that has previously been loaded, media white point, adding the correct media black point and LUT data tags to the profile.
The ICC profile should then be 'Named' using the internal 'ProfileDescriptionTag', listed within the 'Tag ID' window. This name is the one shown in any ICC profile list called up within ICC compliant programs, so it is important to use a unique name.
Select the Save Profile button to save the profile, and enter the same name as used above in the ProfileDescriptionTag. After saving, the Validate Profile button can be used to versify the integrity of the new profile.
Note: SpaceMan, by default, generates mono-direction ICC profiles, as the complex 3D LUTs used as the input data are next to impossible to invert, making such a function useless. The alternative LUT Tag (BToA or AToB, depending on the Class if ICC being generated) is populated with Null/Bypass data.
VCGT
SpaceMan can add a VCGT to the ICC profile, using a 3D LUT as the basis for the 1D VCGT data.
If the vcgtTag information line is double clicked a new window will open showing the VCGT data, both as a numerical list and as a Gamma Graph. The Apply button will apply the VCGT to the active display, and the Reset Display Tables button (monitor icon with green looping arrows, or the F5 key) will re-set the VCGT data - only when the vcgtTag window has been closed.
Note: This is the same operational functionality as SpaceMatch DCM.
As with any Graphics Card based calibration, the VCGT is based on 1D LUT data, not 3D, so the calibration is gamma and colour temperature (grey scale) only, as Graphics Cards cannot control display gamut.
This is true for ANY Graphics Card or Windows OS wide (ICC) calibration.
(Mac can perform OS wide Gamma and Gamut ICC based calibration, but suffers a number of other colour related issues that makes it impossible to rely on such colour calibration.)
SpaceMan Features and Options
SpaceMan is really a bit of a Swiss Army Knife, with a range of tools and capabilities that can be used as needed. This means the actual capabilities of SpaceMan ICC are very difficult to pin-down, as the various tools can be used in a wide variety of ways.
If just making an ICC profile that matches an existing 3D LUT for use in the likes of Photoshop for Look Management the requirements for operation of SpaceMan ICC should be simple, and exactly as described here.
Note: the New Tag button is presently not active. To load a different Tag into an ICC profile first export the desired tag from another ICC profile and load into the profile that lacks it.
Display Calibration
Generating a Display Class ICC profiles is one of the obvious capabilities of SpaceMan, converting an accurate 3D Calibration LUT into an ICC profile. The ICC profile will be a perfect match to the original 3D LUT.
A major benefit of the use of a v4 ICC profile with a ColourSpace 3D LUT loaded into it is the ability to maintain calibration accuracy, as ColourSpace has done all of the hard work in generating the calibration LUT, meaning the graphics program and associated CMM using the ICC has no processing to perform at all. It just passes the image through the 3D LUT data held within the ICC.
To generate a Display Calibration ICC profile first use ColourSpace to generate an accurate calibration 3D LUT. With the LUT generated use SpaceMan to build a Display class ICC profile, using the instructions above.
It is possible to use the VCGT option within SpaceMan to enable OS wide gamma/grey scale/white point calibration within Windows, via the 1D LUT capability of the graphics card. However, the graphics program will probably double-up this correction when the 3D LUT held within the ICC profile is applied, requiring the VCGT to be disabled for accurate display calibration.
If you want to use the VCGT for OS wide gamma/grey scale/white point calibration, the doubling-up can easily be avoided by generating a second 3D LUT within ColourSpace that has no 1D component. The original 3D LUT with the 1D component can then be imported into the ICC profile, with the Build VCGT Tag option enabled to correctly build the VCGT. The second 3D LUT exported from ColourSpace without the 1D component can then be imported into the same ICC with Build VCGT Tag disabled, replacing the 3D LUT component of the ICC for accurate gamma correction, removing the doubling-up of the 1D LUT data.
An alternative approach is to initially profile using a Grey Only profile, as only the 1D grey scale component is of interest, and generate an ICC with the VCGT included. Load the ICC, and with the VCGT active, re-profile using a large Cube based profile to re-profile the display. The generated LUT will therefore not contain the same duplicated 1D data, but will contain the 3D volumetric gamut data.
To Load the Calibration ICC profile into Windows use the Windows Colour Management option, found via the Control Panel, after first installing the ICC profile by right clicking it, and selecting Install Profile.
(A Google search will find instructions for the loading of Display Calibration ICC profiles for your specific Windows OS version.)
The ICC profile needs to be associated with the display it will be calibrating, for example via Windows Colour Management, as described above, and activated via enabling Use Windows display calibration. The calibration will then be loaded automatically on startup - including the VCGT, if the ICC was generated with one.
Note: As the ICC profiles generated by SpaceMan ICC use XYZ as the PCS Colour Space, some graphics systems will complain about the profiles potentially being defective when used as DisplayClass profile. Photoshop is an example, complaining that: The monitor profile xxxx appears to be defective. Please rerun your monitor calibration software. Such warnings can be ignored, as using XYZ as the PCS Colour Space is entirely valid.
Look Management
Look Management is another obvious application for SpaceMan ICC, enabling Look LUTs, such as Film Emulation 3D LUTs, to be accurately converted into ICC profiles.
The process is basically as above, selecting Input+BToA Tag as the Profile Type. For such Look Emulation ICC profiles it is not necessary to use the VCGT option, as that is redundant.
Rather than using the OS, Look Emulation profiles should be used within the graphic program. The below describes the use of Photoshop, outlining potential issue that can cause the applied ICC profile to look wrong.
ICC Profile Workflows for LUT Emulation
The following describes the type of image path used with ICC profiles when performing Look LUT emulation when working with Log source images.
Working Space
OS wide Working Colour Space
(for example, sRGB)
-
Source Image
Log Image
-
ICC AToB Tag
AToB Tag within ICC Profile (The converted 3D Look LUT)
-
PCS
Profile Connection Space (XYZ for video image workflows)
-
ICC BToA Tag
BToA Tag within ICC profile (Usually Null/Bypass)
-
Display Calibration
Ideally a 3D LUT in the display or LUT box (or possibly a Display ICC via OS CMM)
-
Display
Correct image display
This image based workflow is broadly generic, but will help understand how ICC profile are applied within Windows OS and Photoshop.
ICC Issues
ICC profiles are very complex as they were developed by a large number of companies and individuals, from a range of industries, all with varying requirements and needs. More importantly, the level of colour accuracy required for ICC profile operation for these companies and individuals doesn't match those of the film and tv industry, as the majority of the requirements have come from the print industry, where colour accuracy is more subjective than absolute, due to the inexact nature of attempting to match different output print mediums while viewing the source images on a monitor.
The film and tv industry relies on a far higher level of colour matching accuracy, due to the similarity of all viewing mediums. This enables far simpler, but far more accurate, colour management to be used, where the display device (display/monitor/projector) is calibrated to a given standard in isolation of any and all input sources.
As a result, understanding ICC profiles can be extremely difficult for those used to the far simpler, and far more accurate, approach to colour and look management used within the film and tv industry.
Therefore, the primary function of SpaceMan is to generate Input+BT0A Tag ICC profiles for use as Look LUT emulations, and the generation of DisplayClass ICC profiles for Display Calibration, although the tools provided within SpaceMan ICC allow for far more options.
Why doesn't my ICC Profile look correct?
When using different graphics programs with the generated ICC profile there can often be unexpected results, due to the numerous ICC options provided within the graphics program, as well as the various additional 'Colour Management' settings within the OS itself. Finding the correct combination can be a bit of a crap-shoot without a high-level of ICC profile understanding, but, as mentioned previously the Input+BToA Tag or DisplyClass options will tend to be the correct defaults, unless you are attempting something very ICC specific, and for which you already have the required knowledge!
Generating the correct ICC profile is only half the battle. Configuring the OS Colour Management settings, as well as the colour management settings with the graphics program to be used, can be the more awkward part of using ICC profiles.
Using Photoshop on Windows as an example, the following are some of the issues to look out for.
Note: The following assumes you have built an ICC profile to match a Look LUT, such as a Film Emulation LUT for viewing on an sRGB display - not a display calibration, or other, ICC profile.
Windows Colour Management
The Windows OS colour management Device Profile needs to be set to match the Working Space, as will be used within Photoshop. Additionally, the use of Absolute Colourimetric is suggested as the Rendering Intent when working on video images, both within Windows Colour Management, and within Photoshop, unless you really understand how ICC profiles work, and are happy to use alternate settings.
Perceptual is another alternative that should work in most situations...
Note: In the above example there is no Display ICC/CMM active as the display is calibrated by an external 3D LUT, not via an ICC profile.
Windows 11, Wide Gamut & HDR
With Windows 11 there is on-going evolution as how to manage wide gamut displays, and HDR.
While this is ongoing, there is one requirement for ICC profiles that SpaceMan doesn't apply by default - the need for Red, Green, and Blue ColorantTags.
Obviously, it is easy to copy such Tags from any other ICC profile, and alter the values as needed.
Just remember the D65 values should be adapted to the D50 white point used in ICC profiles.
Photoshop
If you have a display that can be internally calibrated, or can use an external LUT box, it is best to disable all OS level Colour Management.
- Go to Control Panel, Colour Management
- Start with the Devices tab
- Remove all Profiles associated with any display device
- Go to Advanced tab, Change System Defaults
- Again, Start with the Devices tab
- Remove all Profiles associated
- Go to Advanced tab
- Un-tick the box Use Windows display calibration
- Close everything
Note: If you intend to use ICC based display colour management colour accuracy cannot be guaranteed, due to the potential issues with ICC profile colour management. Please make sure you understand how ICC display calibration workflows are intended to work if using this approach. If you do want to use ICC based display calibration the best approach is to generated the ICC profile via SpaceMan ICC from a 3D Calibration LUT, as outlined above.
Moving on to Photoshop itself, it is best to use a reference frame to compare the same source image with the original LUT burnt in (using ColourSpace for this if needed), and the same frame without the LUT, so when the ICC is applied a direct comparison can be made. As both images are held within Photoshop is is possible to make a direct relative comparison between both of them.
In the above image the original log image is on the left, with the same log image, but with the 3D LUT burnt-in via ColourSpace, on the right. The ICC profile can now be applied to the left image.
From within the Colour Settings menu (found via Edit/Colour Settings) there are options that will directly alter the result of the applied ICC profile, some of which are duplicated within the Convert to Profile menu as well. These are effectively Colour Preferences, and define the colour management policies desired for Photoshop globally.
The next step is to Assign the ICC profile to the selected image, using Assign Profile.
In an ideal world the original image will now look correct, and match perfectly the image with the 3D LUT pre-applied. However, this may not initially be the case, and if happens you will need to re-check all other ICC settings, as above.
An example of the possible issues can be as simple as altering the rendering Intent, Black Point Compensation, the OS based Colour Management Defaults, etc.
It should not be necessary to use the Convert to Profile menu, but in some situations it may be necessary, especially as there is a very irritating bug in some installations of Photoshop where it is necessary to toggle the Destination Space from the selected RGB space to another, and back, before the correct result of the applied ICC profile is seen... but be aware how this changes the way the ICC profile is used within Photoshop, as Photoshop has a nasty habit of effectively burning-in the ICC profile without warning!
Note: 'Assign to Profile' is actually intended to convert from an 'Embedded' ICC profile to another ICC profile, and as the source Log images will not have an embedded ICC should not really be used!
And as a final check, make sure the Proof Colours option is not active, as that will prevent the applied ICC form operating correctly.
With all the above setting correctly configured you should have two identical images within Photoshop - one with the original 3D LUT burnt-in, and the other with the SpaceMan generated ICC profile applied.
If the two images are not identical, the most common issue will be an incorrect configuration within Photoshop, or the Windows OS Colour Management settings. Check everything again... Or, when generating the ICC profile via SpaceMan in the first place, the incorrect RGB colour space was selected.
Note: Rather than the above side-by-side configuration it is actually better to toggle between both image full-screen, so any variation due to incorrect Photoshop settings can be seen.
With the two images matching perfectly your colour management within Photoshop is now set correctly. However, if both image look incorrect when compared to the original image and LUT as used within the original grading system you have a 'calibration' issues, which has nothing to do with the SpaceMan generated ICC profile.
