SPRUJB3 March 2024 AM67 , AM67A , TDA4AEN-Q1 , TDA4VEN-Q1
Table 7-103 shows the key parameters within the iridix core. It is recommended that all parameters be set statically to their recommended values other than the iridix strength parameter, which should be controlled dynamically with scene content. The calculation of iridix strength is explained in Section 7.7.3.5.3.2.
Parameter | Description |
---|---|
iridix strength | This register sets iridix processing strength. |
0x00: Video data will not be processed at all, and will pass to the output unchanged. | |
0xFF: Maximum processing strength. | |
Variance space | This register affects the sensitivity of the transform to different areas of the image, and can be increased in order to emphasize small regions (e.g. faces). If this parameter is set to zero, the sensitivity to small areas is maximized (i.e. the transform becomes more local). When this parameter is set to 0xF, the transform deemphasizes small local details, and the transform becomes more global |
Variance intensity | For a high-contrast image with shadows and highlights, a small value will cause iridix to adjust shadows and highlights almost independently. A large variance causes iridix to become progressively more global, meaning that the presence of highlights affects the processing of shadows and vice-versa. |
Slope min limit | This register is used to restrict the slope of the tone curve generated by iridix. When this parameter is set to 0x00, the tone curve slope generated by iridix is not limited. |
When this value is set to 0xFF, iridix will not generate a tone curve with a slope less than 3/4. Intermediate values of slope limit are linear interpolation between minimum and maximum values. | |
The recommended range of this parameter is 0-128 | |
Slope max limit | This register is used to restrict the slope of the tone-curve generated by iridix. When this parameter is set to 0xFF, the tone curve slope generated by iridix is not limited. |
When this value is set to 0x00, iridix will not generate a tone-curve with slope greater than 16/15 (48°). Intermediate values of slope limit are linear interpolation between minimum and maximum values. | |
The recommended range of this parameter is 0-160. For noisy images, lower values should be used. | |
Black level | The value stored in this register will be used as the zero level for iridix processing in all data channels. Data below this value will not be processed and remain unchanged. |
White level | The value stored in this register will be used as the white level for iridix processing in all data channels. Data above this value will not be processed and remain unchanged. |
Asymmetry LUT | This look-up-table is 33 words, each of which is 16-bits. The asymmetry function is used to balance the iridix effect between the dark and bright regions of the image. |
Forward perceptual LUT | The iridix core works in a perceptually uniform space and thus when linear data is presented to the core, this look-up-table must be used to map the linear data to the perceptual space so that iridix can perform tis perceptual functions. |
Reverse perceptual LUT | The iridix core works in a perceptually uniform space and thus when linear data is required from the output of the core, this look-up-table must be used to map the data from the perceptual space back to linear space for further processing in the pipeline. |