Eyeon:Manual/Fusion 6/Blur
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The Blur tool does exactly what its name implies - it blurs the input image. This is one of the most commonly used image processing operations.
Controls
The Filter Type button array allows for the selection of the filter to be applied to the image.
Box Blur This option applies a Box Blur effect to the whole image. This method is faster than the Gaussian blur but produces a lower quality result.
Soften Soften applies a general softening filter effect. This filter method is slower than the Gaussian filter, and produces a lower quality result. It is included for compatibility with older flows only.
Bartlett Bartlett applies a more subtle, anti-aliased blur filter.
Multi-Box Multi-Box uses a box filter layered in multiple passes to approximate a Gaussian shape. With a moderate number of passes (e.g. 4), a high quality blur can be obtained, often faster than the Gaussian filter, and without any ringing.
Gaussian Gaussian applies a smooth, symmetrical blur filter, using a sophisticated constant-time Gaussian approximation algorithm. In extreme cases, this algorithm may exhibit ringing see below for a discussion of this. This mode is the default filter method.
The filter defaults to operating on R, G, B and A channels. Selective channel filtering is possible by clicking the check boxes beside each channel to make them active or inactive
Note that this is not the same as the RGBA checkboxes found under the common controls. The Blur tool takes these selections into account before it processes the image, so deselecting a channel will cause the tool to skip that channel when processing, speeding up the rendering of the effect.
In contrast the channel controls under the Common controls tab are applied after the tool has processed.
Locks the X and Y blur sliders together for symmetrical blurring. This is checked by default.
Sets the amount of blur applied to the image. When the Lock X and Y control is deselected, independent control over each axis is provided.
This option sets the mode used to handle the edges of the image when performing domain of definition rendering. This is profoundly important for tools like Blur which may require samples from portions of the image outside the current domain.
The default option is Frame, which automatically sets the tools domain of definition to use the full frame of the image, effectively ignoring the current domain of definition. This is identical to the way Fusion worked in versions prior to 6.0.
If the upstream DOD is smaller than the frame, the remaining area in the frame will be treated as black/transparent.
Setting this option to Domain will respect the upstream domain of definition when applying the tools effect. This can have adverse clipping effects in situations where the tool employs a large filter.
Setting this option to None will not perform any source image clipping at all. This means that any data required to process the tools effect which would normally be outside the upstream DOD will be treated as black/transparent.
This is a cloned instance of the blend slider in the common controls tab. Changes made to this control are simultaneously made to the one in the common controls.
The blend slider mixes the result of the tool with its input, blending back the effect at any value less than 1.0.
Tips for Blur (edit)
This is a comparison of blur filters visualized as "cross-sections" of a filtered edge. As you can see, box will create a linear ramp, while Bartlett creates a somewhat smoother ramp. Multibox and Gaussian result in even smoother ramps that are virtually indistinguishable unless you zoom in really close on the slopes. As mentioned above, Gaussian will overshoot slightly and may result in negative values if used on floating point images.
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