Tuning the Tone Map Feature

This section describes how to tune the Tone Map feature to control the tone mapping module in the HDR pipeline of a DC9400.

Before you begin

Make sure:

The details view shows the settings of the Tone Map feature.
To tune this feature, you need to choose DC9400 > HDR > Tone Map in the Features view. For more details, see Tuning a DC9400 Feature.

Figure 1. Details View When Tone Map under HDR Is Selected
A VTunerServer is accessible.
For information about how to set up a connection to a VTunerServer, see Setting Up a Connection to a VTunerServer.

Procedure

Select the Enable Tone Map check box to enable the tone mapping module in the HDR pipeline.
From the YMode drop-down list, select one of the following options to specify the pseudo Y calculation mode:
- VS_DPU_CALCU_LNR_COMBINE: the pseudo Y is derived from a linear combination of R, G, and B values as follows:
  $Y_{linear_combination} = (\begin{matrix} Coef0 & Coef1 & Coef2 \end{matrix}) (\begin{matrix} R_{in} \\ G_{in} \\ B_{in} \end{matrix})$
  where Coef0, Coef1, and Coef2 need to be specified.
- VS_DPU_CALCU_MAX: the pseudo Y is derived from the maximum value among the R, G, and B components as follows:
  $Y_{\max} = MAX (R_{in}, G_{in}, B_{in})$
- VS_DPU_CALCU_MIXED: the pseudo Y is derived from a linear combination of the preceding two values as follows:
  $Y = (Y_{linear_combination} \times Weight + Y_{\max} \times (1024 - Weight) + 512) >> 10$
  where the weight needs to be specified in addition to Coef0, Coef1, and Coef2.
If VS_DPU_CALCU_LNR_COMBINE or VS_DPU_CALCU_MIXED is selected for YMode, enter the coefficients in the Coef0, Coef1, and Coef2 spin boxes.
Each coefficient must be in U12.0 format.
If VS_DPU_CALCU_MIXED is selected for YMode, enter the weight in the Weight spin box.
The weight must be in U10.0 format.
From the LUT Mode drop-down list, select one of the following options to specify the method to configure the 33-entry, piecewise linear LUT:
- Reinhard Curve: automatically generates the basic gain curve, and uses a built-in algorithm to obtain the LUT based on the custom settings of Max Luma, Adjust Formula, and Adjust Coef with relatively small errors.
- User Defined Curve: generates the basic gain curve from a .csv file that contains curve inputs, and uses a built-in algorithm to obtain the LUT based on the custom settings of Max Luma and Adjust Formula with relatively small errors.
- User Defined LUT: imports the LUT from a .csv file that contains LUT inputs.
The LUT is used to re-map pseudo Y values as shown in the chart on the right of the upper section. In this chart, the horizontal axis indicates input RGB values and the vertical axis indicates the output RGB values.

The LUT curve is displayed on the left of the lower section with its segment points, segment steps, and LUT data listed in tables on the right. In the LUT curve chart, the horizontal axis indicates the pseudo Y value corresponding to the input RGB value and the vertical axis indicates the RGB gain corresponding to each pseudo Y value.
If Reinhard Curve is selected for LUT Mode, perform the following steps:
- In the Max Luma spin box, enter the maximum abscissa of the basic gain curve.
  The value must be greater than 1. The default value is 16.0.
- In the Adjust Formula spin box, enter a value to adjust the overall shape of the basic gain curve.
  A value greater than 1 lowers the curve and vice versa.
  The default value is 1.0. A value from 0.1 to 10.0 is recommended.
- In the Adjust Coef spin box, enter a value to adjust the shape of the dark part of the basic gain curve.
  A value greater than 1 raises the dark part of the curve, and vice versa. A greater value leads to more obvious improvement effects. However, an excessively large value will lead to a non-monotonic curve.
  The default value is 1.0. A value from 0.1 to 1.5 is recommended.
If User Defined Curve is selected for LUT Mode, perform the following steps:
- To the right of Curve Source, click Browse and select a .csv file that contains inputs for the curve.
  It is recommended that the file contains 1025 inputs for the curve.
- In the Max Luma spin box, enter the maximum abscissa of the basic gain curve.
  The value must be greater than 1. The default value is 16.0.
- In the Adjust Formula spin box, enter a value to adjust the overall shape of the basic gain curve.
  A value greater than 1 lowers the curve and vice versa.
  The default value is 1.0. A value from 0.1 to 10.0 is recommended.
If User Defined LUT is selected for LUT Mode, click Browse to the right of LUT Source and select a .csv file that contains the LUT data to generate the curve.

Results

The tuning results are printed in the Console view in real time.
The image displayed on the VTunerServer side is updated.