It makes it possible to create slow transitions from dark to bright areas. It reduces jittery behavior from adapting quickly to small fluctuations in luminance. Using both traversal methods improves two side effects of using only exponential movement: To handle this perceptual movement, the adaptation algorithm traverses the curve with linear and exponential movement. The exposure compensation moves along the curve toward its Target value in f-stops per second. The rate at which exposure compensation adapts to the current scene is done in logarithmic steps that perceptually move up and down the curve at the same rate of speed. Also, this command only supported Auto Exposure Basic metering mode, while the exposure metering mask supports both Histogram and Basic metering modes. This command applied weighting values uniformly across the screen, providing similar functionality that is now handled by creating your own metering mask. With the release of Unreal Engine 4.25, the console command r.EyeAdaptation.Focus has been removed. Giving importance to pixels toward the center of the screen rather than along the edges helps stabilize auto exposure (see the example below). The Exposure Metering Mask gives artists an optional texture slot to control the influence of auto exposure for the whole screen, where each pixel is weighted in importance by the assigned texture mask. They also provide an explanation why the exposure compensation is behaving in a specific way by separating these values.Īverage EV100 is the calculated target EV100 value, and is represented by the target (blue) line in the histogram.Įxposure Compensation (Settings) is the exposure compensation value set in the post process settings.Įxposure Compensation (Curve) is the resulting Y-axis value in a Curve Asset assigned to the Exposure Compensation Curve slot in the post process.Įxposure Compensation (All) is the sum of the settings and curve exposure compensation values resulting in the final exposure compensation value. The Exposure Compensation values are split into their own settings and curve values, giving you more precise control over how you adjust them. Also note that the editor EV100 override setting directly sets the EV100 exposure used in this equation. You can verify this formula's result by disabling the tonemapper through the viewport show flags ( Show > Post Processing), and inspect the scene brightness using the Pixel Inspector. Otherwise, it is 0.ĮV100 = log2(Aperture^2 / Shutter Speed * 100/ISO)Įxposure in the following formula defines the relationship between the scene surface luminance (L, which is measured in cd/m2) and pixel brightness (B) before the tonemapper and exposure compensation are applied. If Apply Physical Camera Exposure is applied, EV100 is calculated as the following formula. If Apply Physical Camera Exposure is disabled in the post process settings, the exposure value will be linear brightness:Įxposure = 1/(2^(EV100 + Exposure Compensation))
#How to open preset thumbnails in exposure x manual#
The Manual metering mode allows the user to select a single, fixed exposure value that is unaffected by the luminance in the scene. In photography, this middle gray point is sometimes referred to as "18% gray" or "18% middle gray," referring to the amount of light that is reflected by a gray card. However, once the average luminance value is determined, both algorithms treat that luminance as middle gray. The Basic and Histogram modes use different algorithms to calculate the average luminance of the scene. Then, the histogram is analyzed to determine the average luminance value. The Auto Exposure Histogram mode first calculates a histogram of the log luminance scene. The Auto Exposure Basic algorithm uses the average of the log luminance of the scene to determine the target exposure value. Manual mode enables the use of Camera settings within the Post Process and Cameras settings to control exposure, rather than using only the settings found in the Exposure category.Īuto Exposure Basic and Auto Exposure Histogram metering modes both calculate the overall luminance of the scene, and brighten or darken the scene to an expected value, but they differ in how they calculate scene luminance. This is the default exposure metering mode in Unreal Engine.Īuto Exposure Basic mode provides fewer settings, but is a faster method that computes single values by downsampling exposure. These different metering modes provide settings that accurately mimic real-world cameras, giving you control over exposure in your scenes through the post process.Īuto Exposure Histogram mode provides finer control over auto exposure with advanced settings constructed from a 64-bin histogram. The engine offers several types of metering modes to choose from when setting up auto exposure in your scenes.
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