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# HDR to SDR Conversion

MK.IO Beam supports HDR-to-SDR conversion for decoded video, compressing the dynamic range of HDR
content to ensure compatibility with standard dynamic range (SDR) systems.

### Supported HDR formats

Conversion is supported for the following HDR formats:

* PQ10/HDR10

* HLG10

Inputs in these formats are tone-mapped to SDR, producing an SDR signal with transfer characteristics
compliant with BT.709, as defined by the selected tone-mapping lookup table (LUT).

## Configuring HDR to SDR Conversion

### Enabling Dynamic Range Conversion

Each Receiver service can be configured for HDR to SDR conversion. Before you start, ensure at
least one Receiver service is configured.

* From the Home page, select the RECEIVER item from the required feed then click .

* In the Parameters window, select the Output tab.

* Configure HDR-to-SDR conversion by setting the Dynamic Range Conversion option to one of
  the following selections:

None: HDR-to-SDR conversion is disabled; the video is passed through unchanged

* Custom HDR to BT.709 lookup table: Use the specified custom LUT to output BT.709 encoded SDR

* Convert to BT.709: Use proprietary tone-mapping LUT to output BT.709 encoded SDR

* If Dynamic Range Conversion has been set to Custom HDR to BT.709 lookup table then select
  the required custom LUT description from the Custom HDR to BT.709 lookup table drop-down option.

* Click Save and continue to save your changes.

* If the incoming stream is already SDR, conversion is automatically bypassed.

* It cannot be verified whether a selected custom LUT is compatible with the
  supported HDR formats listed above, so care should be taken when
  selecting custom LUTs.

* If an issue occurs during HDR-to-SDR conversion, an alarm is raised.

## HDR to SDR Conversion Lookup Tables

HDR-to-SDR conversion uses **3D look-up tables (3D LUTs)**, provided as **.cube** files, to map input
RGB values to output RGB values within a three-dimensional grid, enabling complex colour transformations.

MK.IO Beam supports **size 33** LUTs.

### Viewing Stored LUTs

Multiple LUTs can be stored on MK.IO Beam and individually selected by a Receiver service.
The **Stored LUTs** section lists custom LUTs which have been uploaded to the MK.IO Beam device:

* Select  Appliance from the left-hand side menu.

* Click the HDR > SDR Conversion tab.

Each row in the **Stored LUTs** section provides the following information and their current settings.
Some settings can be modified and saved using the **Update** button.

| Parameter         | Description                                                                                                                                                                  |
| ----------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description       | The reference description given to the custom LUT. This will be listed in the selection when configuring HDR to SDR conversion in the Output settings of a Receiver service. |
| Filename          | The filename of the .cube file that was uploaded.                                                                                                                            |
| Input Full Range  | This determines whether input samples are processed using the full (EBU R 103) range or the standard (limited) YUV range.                                                    |
| Output Full Range | This determines whether output samples are processed using the full (EBU R 103) range or the standard (limited) YUV range.                                                   |
| Creation Date     | Date and time when the custom LUT was uploaded.                                                                                                                              |
| Last Modified     | Data and time when the custom LUT was last modified.                                                                                                                         |
| File CRC          | Unique CRC value of the .cube file that was uploaded.                                                                                                                        |
| Actions           | Possible actions for the custom LUT: - Update : Any modifications must be saved by using this button - Delete : Delete the custom LUT from the device                        |

### Built-in LUTs

MK.IO Beam includes built-in 3D LUTs. These do not appear in the **Stored LUTs**
table on the  **Appliance** pages, but are available for selection when
configuring HDR to SDR conversion in the Output settings of a Receiver service. See the
[Configuring HDR to SDR Conversion](#configuring-hdr-to-sdr-conversion) section for more information.

### Uploading Custom LUTs

To upload additional LUTs, follow these steps:

* Select  Appliance from the left-hand side menu.

* Click the HDR > SDR Conversion tab.

* Select the Upload LUT textbox. A file explorer window will appear.

* Use the file explorer to navigate to the LUT file to upload. Only .cube files will be accepted
  by MK.IO Beam.

* Click the Description testbox to add a unique description of the LUT so that it can be easily
  referenced when enabling Dynamic Range Conversion.

* Enable or disable the Input Full Range setting as required.

* Enable or disable the Output Full Range setting as required.

* Once the settings are complete, click the Upload button to store the custom LUT on the device.