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Camera Imager Settings
The Camera Imager setting provide useful parameters for post-rendering adjustments. Similar to the post processing settings, changing the settings during rendering does not have effect on the rendering progress and will continue. (i.e. changing the camera stops the rendering and will start all over from scratch). Select the Imager Node in the Node tree to adjust the Imagers settings (see figures below).
The Camera Imager parameters :
- Exposure - Controls the exposure of the scene. Smaller values will create a dark scene while higher values will brighten the scene.
- Highlight Compression -This reduces burned out highlights by compressing them and reducing their contrast.
- Order -This defines the order in which the Response curve, the and the Custom LUT is applied on the scene. Typically, 3D LUTs are defined for sRGB input values, i.e. you usually want to apply the custom LUT last, but there might also be 3D look-up Tables for linear input data in which case you might want to apply the custom LUT first.
- Response Curve -The use of measured camera response curves can be selected. Octane also has response curves that reproduces the rendering neutrally on a normal display. The ‘sRGB", "Gamma 2.2" and "Gamma 1.8" are applicable for most displays that either use sRGB or simply apply a gamma of 2.2 or 1.8.
Refer to section Camera Response Curves in this Chapter for image overview.
Note: The most common response curve is "sRGB", hence this is also the default setting in the Camera Imager Node. Since this option did not exist in earlier versions of Octane, any scene with a response curve "sRGB" in the imager settings will fall back to "linear/off" in older versions.
For examples of all the camera responses, see the Appendix topic on Camera Response Curve.
- Neutral response - If enabled, the camera response curve doesn't tint the render result anymore. In the following example (figure 3), the left image is the material ball rendered with no response curve and gamma set to 2.2. The center image uses the Agfacolor HDC 200 curve and a gamma of 1. The right image shows the same curve with "neutral response" enabled.
Figure 3: Adjusting the Neutral Response curve
- Gamma -This adjusts the gamma of the render and controls the overall brightness of an image. Images which are not properly corrected can look either bleached out, or too dark. Varying the amount of gamma correction changes not only the brightness, but also the ratios of red to green to blue.
- Custom LUT -This allows you to specify any standard or user-defined 3D Lookup Table (.cube file) for Octane to map one color space to another. If this attribute is set, the custom LUT is applied in the order specified through the Order attribute.
- White Point -Specifies the color used to adjust the tint to produce and simulate the relative temperature cast throughout the image by different light sources. The white point is white by default, acting as a white balance which helps achieve the most accurate colors possible.
- Vignetting - Adjusting this parameter increases the amount of darkening in the corners of the render. Used sparingly, it can greatly increase the realism of the render. Note also that vignet is not applied to any of the beauty passes except the main pass.
- Saturation - Adjusts the amount of color saturation of the render.
- Hot Pixel Removal - The Hot Pixel Removal slider is used to remove the bright pixels (fireflies) during the rendering process. While many of the pixels can disappear if the render is allowed to progress, the Hot Pixel Removal feature allows the bright pixels to be removed at a much lower Sample per Pixel.
- Pre-Multiplied Alpha - Checking the Pre-multiplied Alpha button multiplies any transparency value of the output pixel by the pixels color.
- Disable Partial Alpha - Option to make pixels that are partially transparent (alpha → 0) fully opaque.
- Dithering - Adds random noise which removes banding in very clean images.
- Saturate To White - When the sun is too bright , it can create multi-colored reflections. Increasing this value will change the colors to white. This is also applicable to all sources of light. Fully saturated parts of the render can be pushed towards pure white with this option. This helps avoid large patches of fully saturated colors caused by over-bright light sources such as very bright colored emitters or reflected sunlight off colored surfaces.
- Minimum Display Samples - This is minimum amount of samples that is calculated before the image is displayed. This feature can significantly reduce the noise when navigating and is useful for real-time walkthroughs. When using multiple GPUs, it’s recommended to set this value as a multiple of the number of available GPUs for rendering, e.g. if you’re rendering with 4 GPUs, set this value at 4 or 8.
- Maximum Tonemap Interval - Maximum interval between tonemaps in seconds.
The Camera Imager parameters related to Denoising:
- Enable Denoising - Enables the spectral AI denoiser, which will denoise some beauty passes including the main beauty pass and writes the outputs into separate render passes.
- Denoise Volumes - If enabled, the spectral AI denoiser will denoise volumes in the scene. Otherwise, volumes are not denoised by default.
- Denoise on Completion - If Enabled, beauty passes will be denoised only once at the end of a render. This option should be disabled while rendering with an interactive region.
- Minimum Denoiser Samples - Minimum number of samples per pixel until denoiser kicks in. This is only valid when the Denoise on Completion (denoise once) option is off.
- Maximum Denoiser Interval - Maximum interval between denoiser runs (in seconds). This is only valid when the Denoise on Completion (denoise once) option is off. The Denoise Interval tells the denoiser to run when this value/threshold is reached. It is mainly used for Interactive render region, which will render up to 1 million (or until stopped). For this specific reason, Octane provides the option to denoise periodically.
- Blend - A value between 0.f to 1.f to blend the original image into the denoiser output. Setting 0.f results with fully denoised image and setting 1.f results with the original image. An intermediate value will produce a blend between the denoised image and the original image.
The Camera Imager also allows control of the Spectral AI Denoiser. Refer to the section on (Spectral AI) Denoiser.
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