ZConvolve Convolves areas of the source clip using a kernel which is made larger or smaller using depth values from a ZBuffer input. Separates the input into a number of layers and applies different sized convolution blurs depending on the distance from the focal depth, and depth of field. This is similar to ZDefocus but with an iris shape (or Kernel) that comes from a clip. Inputs: Source:  The clip to be processed. Kernel:  The filter kernel or shape for the convolution. This should normally be all black around the edges (outside the specified Kernel Crop region), with a non-black central part. A larger shape normally produces blurrier results. Only the part of the kernel within the two Kernel Crop params is considered; the part outside that boundary is ignored. ZBuffer:  The input clip containing depth values for each Source pixel. These values should be in the range of black to white, and it is best if not anti-aliased. Normally black corresponds to the farthest objects and white to the nearest, though this can be adjusted using Z Buffer parameter.

Parameters:

Focal Depth:   Default: 0,  Range: any.
The depth of the focus plane; 0 is near and 1 is far. Areas with this Z value will be in focus. Objects near this depth may be in focus depending on the Depth of Field parameter. You can use Show: In Focus Zone to show the Focal Depth when adjusting. If the effect of this parameter seems backwards, you can invert the depth values using the Z Buffer parameter.

Depth Of Field:   Default: 0.1,  Range: 0 to 1.
Specifies how wide a range of depths near the Focal Depth will be in focus. If the Focal Depth is 0.5 and Depth of Field is 0.2, all objects with Z values from 0.4 to 0.6 will be in focus. Set to zero to have only objects exactly at the Focal Depth in focus. You can use Show: In Focus Zone to show this when adjusting.

Size:   Default: 1,  Range: 0 or greater.
The maximum amount to resize the kernel larger or smaller. 1.0 is the original size. This parameter can be adjusted using the Size Widget.

Layers:   Integer,  Default: 5,  Range: 2 to 50.
The number of depth layers to separate the source into. More layers require more processing but give smoother results in Z. More layers are sometimes needed to avoid visible seams between the layers.

Mode:   Popup menu,  Default: Interp Layers.
Determines how the differently blurred layers are combined.

Comp Layers:  the closer layers are composited over the farther layers. This method often gives better results if you have objects at different depths overlapping each other with discontinuous values in your depth image. However, this option can be slower, and sometimes artifacts between layers are visible.

Interp Layers:  the layers are interpolated using depth image values. This method gives smoother transitions between layers, and is usually better if there are no sharp changes in your depth image.

Z Buffer:   Popup menu,  Default: White is Near.
How to interpret the values in the Z buffer.

Black is Near:  Black pixels in the Z buffer indicate that the object at that point is near (close to you), and white means far away.

White is Near:  White pixels in the Z buffer indicate that the object at that point is near (close to you), and black means far away.

Show:   Popup menu,  Default: Result.
Selects the type of output.

Result:  Show the final output.

Kernel:  Show the convolve kernel over the final output. Use this to adjust the kernel cropping and threshold parameters.

In Focus Zone:  Show the in-focus zone highlighted over the original image. Use this to adjust the focal depth and depth of field.

Size Rel X:   Default: 1,  Range: 0 or greater.
Increase to make the kernel fatter or wider without changing its height. Decrease to shrink it horizontally, making it thinner.

Size Rel Y:   Default: 1,  Range: 0 or greater.
Increase to make the kernel taller without changing its wieght. Decrease to shrink it vertically, making it flatter.

Autoscale:   Popup menu,  Default: Luma.
In convolution, either a larger or brighter kernel will make the result image brighter. The kernel must be auto-scaled or normalized so the result is, on average, as bright as the input. The autoscaling can be done in several ways, each of which is best in certain circumstances. With a monochrome kernel or with Color Kernel turned off, Max Channel, Luma, and Indep Channels all give the same result.

Luma:  Autoscales the kernel by summing the luminances of each kernel pixel. This method preserves changes in the kernel's hue, but normalizes the luma, so a brighter or darker kernel will have no effect. Use the Scale parameter to adjust the result brightness.

Count Nonzero:  Count how many kernel pixels are nonzero (brighter than black), but otherwise ignore how bright they are. This method is best if you want variations in kernel hue and luma to show up in the result. But blurring the kernel will give a dimmer result, since there will be more nonzero pixels.

Kernel Threshold:   Default: 0.001,  Range: 0 or greater.
Any kernel value below this will be treated as black. It's important for the edges of the kernel image to be completely black, or the result will have a grayish cast to it. If your kernel image may have a little noise in the black areas, turn up threshold a little to remove that background noise.

Clamp Below Threshold:   Check-box,  Default: on.
When turned on, values below the threshold are clamped to zero. This usually gives the best result. For certain special cases with partially-negative kernels, turning this off gives you additional flexibility in designing your kernel.

Edge Mode:   X & Y,  Popup menu,  Default: [BLACK BLACK].
Determines the behavior when accessing areas outside the source image.

BLACK:  Areas outside the source image are treated as black, which can produce dark areas around the edges of the image. Select this for fastest rendering.

REPEAT:  Repeats the last pixel outside the border of the image.

REFLECT:  Reflects the image outside the border.

Kernel Center:   X & Y,   Default: [0 0],  Range: any.
The center point of the kernel; if you think of convolution as repeated stamping of the kernel at each point of the source, the center is where the stamp aligns with the source pixels it's stamped over. If you move the center to the right in the kernel, the whole result image will move to the left, and similarly up and down. This parameter is ignored if AutoCenter is on. It may be helpful to turn on Show Kernel while adjusting this parameter. Note that if Autocenter is off, the center point is always included in the kernel no matter what this param is set to. This parameter can be adjusted using the Kernel Center Widget.

Combine:   Popup menu,  Default: Convolve Only.
Determines how the convolved image is combined with the original source.

Convolve Only:  Only show the convolved image. Use this option for a blur or defocus-like effect

Screen:  Screen the convolved image with the original source. Use this option for a glow or glare-like effect.

Add:  Add the convolved image to the original source.

Difference:  Show the difference between the convolved image and the source.

Autocenter:   Check-box,  Default: on.
Automatically finds the center of the kernel image. Turning this on makes the effect ignore the Kernel Center parameter.

Size Rel Near:   Default: 1,  Range: 0 or greater.
Scales the kernel size for parts of the image that are nearer than the focal plane.

Size Rel Far:   Default: 1,  Range: 0 or greater.
Scales the kernel size for parts of the image that are farther away than the focal plane.

Use Gamma:   Default: 1,  Range: 0.1 or greater.
Values above 1 cause highlights in the source clip to keep their brightness after the convolution filter is applied.

Brightness:   Default: 1,  Range: 0 or greater.
Scales the brightness of the result.

Mix With Source:   Default: 0,  Range: 0 to 1.
Interpolates between the convolved result (0) and the original source (1). 0.1 can give a nice misty effect since it mixes only a little of the source in.

Params2:

Threshold:   Default: 0,  Range: 0 or greater.
Any source value below this will be treated as black. When combining the convolved result with the original, you can increase this value to only convolve bright areas of the source. Typically when using this parameter, you will also set Combine to Screen or Add to get a glare-like effect.

Kernel Crop1 X:   Default: 0,  Range: any,  Shared.
With Kernel Crop1 Y, forms upper left corner of the kernel area. Parts of the kernel image outside the rectangle defined by Kernel Crop1 and Kernel Crop2 are assumed to be black. Making this area smaller to avoid processing the kernel's black edges can speed up the convolution somewhat. It may be helpful to turn on Show Kernel while adjusting this parameter. Note that if Autocenter is off, the center point is always included in the kernel no matter what this param is set to.

Kernel Crop1 Y:   Default: 0,  Range: any,  Shared.
Upper left Y coord of kernel crop rect.

Kernel Crop2 X:   Default: 1e+04,  Range: any,  Shared.
The lower right X corner of the kernel area; see Kernel Crop1.

Kernel Crop2 Y:   Default: 1e+04,  Range: any,  Shared.
The lower right Y corner of the kernel area; see Kernel Crop1.

Boost Highlights:   Default: 0,  Range: 0 or greater.
The amount to increase the luma of the highlights in the source clip. Increase this parameter to blow out the highlights without affecting the darks or mid-tones.

Threshold Add Color:   Default rgb: [0 0 0].
This can be used to raise the threshold on a specific color and thereby reduce the convolved result generated on areas of the source clip containing that color.

Hilite Threshold:   Default: 0.9,  Range: 0 or greater.
The minimum luma value for highlights. Pixels brighter than this will be brightened according to the Boost Highlights parameter.

See Also:

ZDefocus ZBlur ZGlow ZFogLinear

Convolve RackDefocus Glare

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