BPR Filters
From ZBrush Info
BPR filters (located in the Render > BPR Filters menu) are post-process effects applied to your Best Preview Render. There are several advantages to using these filters. First, it avoids the extra step of doing post-render work in another program like Photoshop. Second, the BPR filters can use internally computed information like depth or masking. This means you can apply the effects to a local area rather than to the entire image. This local application of the filters is also what sets BPR filters apart from the other render filters from previous versions of ZBrush.
ZBrush provides 13 different types of filters which may be layered on top of each other at will. Keep in mind that because these filters are applied to a Best Preview Render, their effects will only appear after a BPR render has been completed. To enable or disable a specific filter layer, click on the small circle at the top right corner of the BPR filters. Filters are similar to Layers in 2D software and each is applied on top of those beneath it in the stack. This means that a different order of the same filters can produce a different result.
The BPR filters are modes. This means that for each new render of your current project, the same filters will be applied, consistently producing the same resulting effect.
Note: When you have created a filter combination that you particularly like you can save it for future use by saving your Project. In the future you can load the Project again, ready for you to load your new model and hit the BPR button.
The BPR filters can use Depth, Fresnel, Shadow, Ambient Occlusion, Sub Surface Scattering and Mask (Alpha) data, along with Color based on Intensity, Hue and/or Saturation information from the render. Some of these items (like Mask and Fresnel) are computed by default. Information like Ambient Occlusion or Sub Surface Scattering are able to be used by the filters only if they have been computed at render time. Simply enabling the filter’s slider will not activate that particular rendering option; you must specifically choose the render options that you desire using the various Render switches. This gives you the flexibility to speed up your test renders by disabling some render options without having to also disable the corresponding filters.
The workflow for using BPR filters is simple: select a filter slot, enable it, choose the filter of your choice and then finally tweak the settings according to your needs. Repeat these steps with another slot to add a new filter on top of the previous one.
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BPR Filters List
ZBrush provides 13 different filters which can be combined and applied to your BPR render. These can modulated by the filter settings and the masking settings.
Noise
applies speckles to the render. The noise color can be modulated by the Color setting located at the right of the Blend mode.
Blur
fuzzes the rendered details. The Color setting has no impact on this filter. This filter is the opposite of the Sharpen filter and so if the Strength slider is set to a negative value this filter will produce a Sharpen effect.
Sharpen
makes the edges and other details in the render more pronounced. This filter is the opposite of the Blur filter and so if the Strength slider is set to a negative value this filter will produce a Blur effect.
Orton
produces a popular photographic effect that superimposes a blurred version of the image with a sharpened version. The result is a soft and slightly blurry image that nonetheless has clear details and vibrant color.
Fade
applies transparency to the render. At 100%, the rendered colors become invisible.
Glow
applies a glow effect to the render. The color of the Glow is based on the render color.
Color
applies a uniform color to the render which can be modulated by the Color setting located at the right of the Blend mode. This filter is applied using the Replace blending mode.
Red
applies a uniform red color to the render using the Screen blending mode. The Color setting has no impact on this filter.
Green
applies a uniform green color to the render using the Screen blending mode. The Color setting has no impact on this filter.
Blue
applies a uniform blue color to the render using the Screen blending mode. The Color setting has no impact on this filter.
Saturation
modifies the color purity within the render. (Red at 100% saturation is pure red while at 0% saturation is colorless gray.) The Color setting has no impact on this filter.
Hue
shifts the colors within the render to a different color. How far the color is shifted away from its starting point is modified by the Strength slider. The Color setting has no impact on this filter.
Intensity
modifies how bright the colors are within the render. A negative for the Strength slider will darken the render while a positive value will lighter the render. The Color setting has no impact on this filter.
BPR Filter Settings
Each filter creates its own unique effect but all filters share the same common settings. However, with some filters there are settings that will not affect the result.
Filter activation and selection
Click on the F1 to F8 buttons to display the corresponding slot which can receive a filter. By default, no filters are activated. You must click on the small circle at the top right of the Function button to enable/disable the filter.
Filter selector
Click to select one of the available filters to apply to your render. The same filter may be applied in multiple slots, with each instance receiving its own settings.
Blend mode
Change the mode by which the filter effect will be combined with your render. Each filter has a default blend mode that will be selected by default but you are free to change it to get the exact result you are looking for.
Color picker
By clicking on the Color box you can change the color applied to the filter. Some filters like Red, Blue or Green are not affected by this option.
Strength slider
Define how strongly the filter will be applied to your render. At 0, the filter has no effect, while at 1 it applies the effect at 100%. Negative values are also possible and will reverse the filter’s effect (such as turning the Blur filter into a Sharpen filter).
BPR Filter Modulators
When a filter is applied to your render its effect and corresponding settings can be modulated by maps derived from the render information. These settings can be used to define where you want to have this effect (like only on shadowed surfaces) or how strongly the effect should be applied in any area (such as applied more strongly where shadows are darkest).
Most of the settings have an Exponential slider which can increase or decrease the corresponding modulator by an exponential curve. A low value means that the effect will spread along the corresponding area while a high value will reduce and concentrate the effect on local areas.
Radius slider
Alter the current filter by increasing its spread. This setting is modulated by the Strength slider
Filter Blur type
Defines the type of the falloff of the Radius information, from the center of the radius to its end.
Depth
Modulates the filter based upon the depth information in the scene. This information is always available and doesn’t need to be enabled in the Render settings to be applied to the image.
Fresnel
Modulates the filter based upon surface orientation. By adjusting the modulator’s value the filter can be applied to the front surfaces of the model or to surfaces angled away from the camera. This information is always available and doesn’t need to be enabled in the Render settings to be applied to the image.
Shadow
Modulates the filter by which parts of the surface are in shadow. When at its maximum value, the filter will only be applied where there are shadows in the render. This information is always available and doesn’t need to be enabled in the Render settings to be applied to the image.
Ambient Occlusion
Modulates the filter based upon how close surfaces are to each other. When at its maximum value, the filter will only be applied where Ambient Occlusion shadows are cast within the render. This information is available only when Ambient Occlusion has been enabled in the Render > Render Properties menu prior to rendering.
Sub Surface Scattering
Modulates the filter by where light is able to pass through the model via its SSS settings. When at its maximum value, the filter will be applied only to the translucent areas within the render. This information is available only when Sub Surface Scattering has been enabled in the Render > Render Properties menu prior to rendering.
Mask
Modulates the filter by the model’s silhouette. When at its maximum value, the filter will be applied only within the parts of the canvas that are covered by your model. With a value of -1 the filter will only apply to the background. This information is always available and doesn’t need to be enabled in the Render settings to be applied to the image.
Color Swatch
The color chosen with this selector will be used as a modulator for a filter. In this way, the filter can be applied only to that color in the render, based upon the Intensity, Hue and Saturation sliders located next to the swatch. If you click and drag from the Color swatch, the cursor will become a Picker with which you can select any color in your render.
Intensity (Int)
Modulates a filter based on the intensity of the color that is selected in the associated Color Swatch. The Int Exp slider will control the size of the intensity roll off being applied to the model. Higher settings will result in less of the render being affected by the filter.
Hue
Modulates a filter based on the hue of the color that is selected in the associated Color Swatch. The Hue Exp slider will control the size of the hue roll off being applied to the model. Higher settings will result in less of the render being affected by the filter.
Saturation (Sat)
Modulates a filter based on the saturation of the color that is selected in the associated Color Swatch. The Sat Exp slider will control the size of the saturation roll off being applied to the model. Higher settings will result in less of the render being affected by the filter.
