Imager

The Camera Imager settings provide useful parameters for post-rendering adjustments. These parameters are in the Imager roll out of a PBR Render Target (Figure 1).

Figure 1: The Camera Imager parameters

Camera Imager Parameters

Exposure - Controls the exposure of the scene. Smaller values darken a scene, while higher values brighten the scene. Exposure has no effect on any render layer passes.
Highlight Compression - Reduces burned-out highlights by compressing them and reducing their contrast.
Order - This defines the order in which the Response Curve, the GammaIn Computer Graphics, gamma refers to the function or attribute used to code or decode luminance for common displays., 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 - Selects the measured camera response curves. OctaneRender^® also has response curves that produce a neutral rendering on a normal display. The sRGB, Gamma 2.2, and Gamma 1.8 curves are applicable for most displays that either use sRGB, or simply apply a gamma of 2.2 or 1.8.
Note: The most common response curve is sRGB, so this is the default setting in the Camera Imager node. Since this option did not exist in earlier versions of OctaneRender, any scene with an sRGB response curve in the Imager settings falls back to Linear/Off in older versions.

For examples of all the camera responses, see the Camera Response Curve topic.
Neutral Response - If enabled, the camera Response Curve won't tint the render result. In the following example (Figure 2), the left material ball is rendered with no Response Curve and Gamma set to 2.2. The center ball uses the Agfacolor HDC 200 curve and a Gamma of 1. The right ball shows the same curve as the center ball, but with Neutral Response enabled.

Figure 2: Adjusting the Neutral Response Curve

Gamma - Adjusts the gamma of the render, and controls the overall brightness of an image. Images that are not properly corrected look either bleached out or too dark. Varying the gamma correction amount changes not only the brightness, but also the ratios of red-to-green-to-blue.

White Point - Specifies the color for adjusting the tint that produces and simulates the relative temperature cast throughout the image by different light sources.

Vignetting - Increases the amount of darkening in the corners of the render. With moderate use, it can increase the realism of the render. OctaneRender doesn't apply vignetting to any of the beauty passes except for the main pass.

Saturation - Adjusts the amount of color saturation for the render.

Hot Pixel Removal - Removes bright pixels (fireflies) during the rendering process. While many pixels can disappear if the render progresses, Hot Pixel Removal removes the bright pixels at a much lower sample per pixel.

Pre-Multiplied Alpha - Multiplies any transparency value of the output pixel by the pixel's color.

Disable Partial Alpha - Makes pixels that are partially transparent (Alpha > 0) fully opaque.

Dithering - Adds random noise, which removes banding in clean images.

Saturate To White - When the sun is too bright, it creates multicolored reflections. Increasing this value changes the colors to white. This applies to all sources of light. You can push saturated parts of the render towards pure white with this option. This helps avoid large patches of saturated colors caused by over-bright light sources, such as bright colored emitters, or reflected sunlight off colored surfaces.

Minimum Display Samples - The minimum amount of samples calculated before the image displays. This feature reduces the noise by a significant amount when navigating, and is useful for real-time walkthroughs. When using multiple GPUs, we recommend setting this value as a multiple of the number of available GPUs for rendering - e.g., if rendering with 4 GPUs, set this value to 4 or 8.

Maximum Tonemap Interval - Maximum interval between tone maps in seconds.

Spectral AI Denoiser

Enable Denoising - Enables the Spectral AI Denoiser. This denoises some beauty passes, including the main beauty pass, and writes the outputs into separate render passes.
Denoise Volumes - If enabled, the Spectral AI Denoiser denoises volumes in the scene. Otherwise, OctaneRender doesn't denoise volumes by default.
Denoise On Completion - If enabled, OctaneRender denoises beauty passes only once at the end of a render. You should disable this option while rendering with an interactive region.
Min. Denoiser Samples - Minimum number of samples per pixel until the denoiser kicks in. Only valid when the Denoise Once option is False.
Max. Denoiser Interval - Maximum interval between denoiser runs (in seconds). Only valid when the Denoise Once option is False.
Blend - Setting to 0 results in a fully denoised image, and setting to 1 results with the original image. An intermediate value produces a blend between the denoised image and the original image.

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