# 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.

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

2. In the **Parameters** window, select the **Output** tab.

3. 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

4. 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.

5. Click **Save and continue** to save your changes.

> **Info:**
> - 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](/beam/receiver/output/hdr-sdr#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:

1. Select `sliders` icon **Appliance** from the left-hand side menu.

2. 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 `sliders` icon **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](/beam/receiver/output/hdr-sdr#configuring-hdr-to-sdr-conversion) section for more information.

### Uploading Custom LUTs

To upload additional LUTs, follow these steps:

1. Select `sliders` icon **Appliance** from the left-hand side menu.

2. Click the **HDR > SDR Conversion** tab.

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

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

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

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

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

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