Paper 72: High Dynamic Range (HDR) image HDR (HI dynamic Range)

In standard rendering, the red, green and blue values for a pixel is each represented by a fraction in the range 0..1, WH Ere 0 represents zero intensity and 1 represents the maximum intensity for the display device. While the-is straightforward-to-use, it doesn ' t accurately reflect the "the" to "lighting works in a real life scene. The human eye tends-to-adjust to local lighting-conditions, so-an object-looks white in a dimly lit-the-in fact Be less bright than a object that looks grey in full daylight. Additionally, the sensitive to brightness differences at the low end of the range than at the high end.

In standard rendering, the red, green, and blue values per pixel represent the range ratio of 0~1, where 0 represents 0 strength and 1 indicates the maximum strength of the display device. While this is intuitive to use, it does not accurately reflect the lighting in real life scenes. The human eye tends to adapt to local lighting conditions, so an object looks white in a darkened room, not brighter than a gray object in daylight. In addition, the brightness difference of the eye in this range is more sensitive than in the high place.

More convincing visual effects can achieved if the rendering are adapted to let the ranges of pixel values more accurate Ly reflect the light levels that would is present in a real scene. Although these values would ultimately need to being mapped back to the range available on the display device, any Intermediat e calculations (such as Unity ' s image effects) would give more authentic results. Allowing the internal representation of the graphics to use values outside the 0..1 range are the essence of high Dynam IC Range (HDR) rendering.

A more convincing visual effect can be achieved if the rendering adapts to the range of pixel values to reflect the light level more accurately, this will be a real scene. Although these values will eventually need to be mapped back to the available range of the display device, any intermediate computations (such as Unity's image effects) will provide more realistic results. Allows internal images to be used, and the outer range of the 0...1 value is High dynamic range (HDR) rendering.

Working with HDR using HDR

HDR is enabled separately-each camera using a setting on the camera component:-

HDR enables the settings individually for each camera component:

When HDR was active, the scene is rendered to an HDR image buffer which can accommodate pixel values outside the 0..1 ran Ge. This buffer was then postprocessed using image effects such as HDR bloom. The tonemapping image effect is what converts the HDR image into the standard low dynamic range (LDR) image to be sent for Display. The conversion to LDR must is applied at some point in the image effect pipeline but it need not being the final step if ldr- Only image effects is to be applied afterwards. For convenience, some image effects can automatically convert to LDR after applying a HDR effect (see Scripting below).

When HDR is active, the scene is rendered into an HDR image buffer that can hold 0. 1 pixel values outside the range. This buffer is then later processed using image effects, such as HDR bloom. The hue map tonemapping image effect is to convert an HDR image to a standard low dynamic range (LDR) image to send the display. Converting to LDR must apply an image effect pipeline at some point, if only the LDR image effect is applied later, but it does not require the last step. For convenience, some image effects can be automatically converted to LDR after applying the HDR effect (see script below).

tonemapping Tone Mapping

Tonemapping is the process of mapping HDR values back into the LDR range. There is many different techniques, and what's is good for one project may isn't the best for another. A variety of tonemapping image effects has been included in Unity. To use them select Assets, Import package, Image Effects (Pro only) Select the camera in the scene then select C Omponent, Image Effects->tonemapping A detailed description of the tonemapping types can be found in the image EF Fects documentation.

Tonemapping is an HDR value that reflects the process of firing back into the LDR range. There are many different technologies that are good in this project and may not be the best in another project. Various tonemapping image effects are included in unity. To use them, select assets, Import package, and image effects (Pro only), select the camera in the scene, and then select component, Image effects->tone Mapping, for a detailed description of the tonemapping type, can be found in the image Effects document documentation.

An exceptionally bright seen rendered in HDR. Tonemapping is used to bring the bright intensities back into the displayable range.

Rendered under HDR see extra bright. The tonemapping is used to reduce the luminous intensity to a range that can be displayed.

HDR Bloom

The

Using HDR allows for much the control in post processing. LDR Bloom have an unfortunate side effect of blurring many areas of a scene even if their pixel intensity are less than 1.0. By using HDR It's possible to only bloom areas where the intensity is greater than one. This leads to a much more desiarable outcome with only super bright elements of a scene bleeding into neighboring pixels. The built in ' Bloom and Lens flares ' image effect now also supports HDR. To attach it to a camera select Assets, Import package, Image Effects (Pro only) Select the camera in the scene Then select Component, Image Effects->bloom (Supports HDR and Lens Flare) a detailed description of the ' Bloom an D Lens flares ' effect can be found in the image effects documentation.

Use HDR to allow more post-processing control. LDR Bloom has some side effects, and many areas of the scene become blurred, even if their pixel strength is less than 1.0. By using HDR, you only bloom areas where the pixel strength is greater than 1. This will result in a scene in which the ultra-high luminance element infiltrates to neighboring pixels for better results. The built-in "Bloom and Lens flares" image effects now also support HDR. Select assets, Import package, image effects (Pro only) to associate it with the camera, select the camera in the scene, and then select component, Image effects->BL Oom (Supports HDR and Lens flare) (HDR and lens flare support), detailed description of the "Bloom and Lens flares" effect, you can refer to the image effects document images of effects documentation.

An exceptionally bright scene where bloom have been applied to intensities greater than 1.0. The bloomed image has also been tonemapped back into the displayable range.

An exceptionally bright scene, where pixel strength >1.0 has been used bloom. Bloom processed images are also tonemapped, changing to a range that can be displayed.

Advantages of HDR (Advantages of HDR)

• Colors not being lost in high intensity areas color is not lost in strong areas
• Better Bloom Support better supports bloom
• Reduction of banding in low frequency lighting areas to reduce the band in the lower frequency illumination area

Disadvantages of HDR (disadvantages of HDR)

• Uses floating point buffers (rendering are slower and requires more VRAM)
  Use floating-point buffers (rendering is slow and requires more memory)
• Not supported on all hardware
  Not all hardware is supported

Usage Notes Usage notes forward Rendering forward rendering

In forward rendering mode HDR was only supported if you had an image effect present. This was due to performance considerations. If you had no image effect present then no tone mapping would exist and intensity truncation would occur. In this situation the scene would be rendered directly to the backbuffer where HDR was not supported.

In forward rendering mode, HDR is only supported if there is currently an image effect in the case. This is due to performance considerations. If you do not currently have an image effect then no tone mapping and intensity truncation will occur. In this case, the scene is rendered directly to a fallback buffer that does not support HDR.

Deferred Rendering Deferred rendering

In HDR mode the light Prepass buffer was also allocated as a floating point buffer. This reduces banding in the lighting buffer. HDR is supported in deferred rendering even if no image effects are present.

In HDR mode, the light Prepass buffer is also allocated as a floating-point buffer. This will reduce the band of the illumination buffer. HDR is supported under deferred rendering, even if no image effects are currently available.

Scripting Script

The Imageeffecttransformstoldr attribute can be added to a image effect script to indicate that the target buffer should is in LDR instead of HDR. Essentially, this means the a script can automatically convert to LDR after applying its HDR image effect.

The Imageeffecttransformstoldr property can be added to an image effect script to indicate that the target buffer should be in LDR, not HDR. Basically, this means that a script can be automatically converted to LDR after applying the HDR image effect.

Paper 72: High Dynamic Range (HDR) image HDR (HI dynamic Range)