The Imager rollout for OctaneRender®in the Nuke Properties window provides a limited set of camera imager controls (figure 1). There is a more extensive set of Camera Imager controls in the OctaneRender window. It is found under the Tonemap Settings in a Render Target node. Note that any settings found in both the Nuke Properties and the OctaneRender window are connected. If, for instance, the Hotpixel Removal is changed in the Nuke Properties, it will automatically change in the Imager rollout in the OctaneRender window as well.
Figure 1: The Imager controls found in the Imager rollout within the OctaneRender node.
A Camera Imager node can also be attached to a Render Target node for easier access to the Imager settings (Figure 2).The Camera Imager node can be found by right-clicking in the Octane Nodegraph Editor window and navigating to the Render Settings category of nodes.
Figure 2: A Camera Imager node connected to a Render Target node in the Octane Nodegraph Editor window.
Exposure - Controls the exposure of the scene. Smaller values will create a dark scene while higher values will brighten the scene. Note also that exposure has no effect on any of the render layer passes.
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 GammaThe function or attribute used to code or decode luminance for common displays. The computer graphics industry has set a standard gamma setting of 2.2 making it the most common default for 3D modelling and rendering applications. 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.
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.
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-Multiply 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 multicolored 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
Spectral AI Denoiser Parameters
Upsampler - OctaneRender® includes a built-in AI upsampler. When specifying an Upsampler Mode, the AI upsampler performs a faster render at a lower resolution, then upscales to the final resolution. The AI Upsampler also has progressive and one-stop upsampling modes, similar to the AI denoiser.