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IDistort

IDistort warps the input image based on the values in the image’s UV channels. The U and V values are offsets for where a pixel will come from. For example, if pixel 51, 23 has a U and V value of -1, 5, the pixel's value will come from 50, 28 of the input channels.

You can use the Copy node to merge the two distortion channels in with your image channels, and then select the two channels from the UV channels dropdown menu.

Inputs and Controls

Connection Type

Connection Name

Function

Input

unnamed

This input needs to include both the channels to distort and the two channels to use to calculate the distortion.

mask

An optional image to use as a mask. By default, the distortion is limited to the non-black areas of the mask.

At first, the mask input appears as triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Control (UI)

Knob (Scripting)

Default Value

Function

IDistort Tab

channels

channels

all

The distortion is only applied to these channels.

If you set this to something other than all or none, you can use the checkboxes on the right to select individual channels.

UV channels

uv

none

The two channels that are used to calculate the distortion for the input image. The U and V values are offsets for where a pixel will come from. For example, if pixel 51, 23 in the above input channels has a U and V value of -1, 5, the pixel's new value will come from 50, 28 of the input channels.

UV offset

uv_offset

0

This is subtracted from the UV channels to set a non-zero center point for renderers that cannot output negative numbers.

UV scale

uv_scale

1

Multiply the UV channels by this value.

blur channel

N/A

disabled

Enable the associated blur channel to the right. Disabling this checkbox is the same as setting the channel to none.

blur

none

Values in this channel are added to the size of the sample area to add extra blur or diffusion to the distortion.

blur scale

blur_scale

1

Adjusts the amount of blur.

mask channel

N/A

disabled

Enable the associated mask channel to the right. Disabling this checkbox is the same as setting the channel to none.

maskChannel

none

The channel to use as a mask. By default, the distortion is limited to the non-black areas of this channel.

invert

invert_mask

disabled

Inverts the mask so that the distortion is limited to the non-white areas of the mask.

premultiplied

premultiplied

disabled

Check this if the UV and blurchannels have been premultiplied by the alpha channel, such as when output by a renderer.

filter

filter

Cubic

Select the filtering algorithm to use when remapping pixels from their original positions to new positions. This allows you to avoid problems with image quality, particularly in high contrast areas of the frame (where highly aliased, or jaggy, edges may appear if pixels are not filtered and retain their original values).

Impulse - remapped pixels carry their original values.

Cubic - remapped pixels receive some smoothing.

Keys - remapped pixels receive some smoothing, plus minor sharpening (as shown by the negative -y portions of the curve).

Simon - remapped pixels receive some smoothing, plus medium sharpening (as shown by the negative -y portions of the curve).

Rifman - remapped pixels receive some smoothing, plus significant sharpening (as shown by the negative -y portions of the curve).

Mitchell - remapped pixels receive some smoothing, plus blurring to hide pixelation.

Parzen - remapped pixels receive the greatest smoothing of all filters.

Notch - remapped pixels receive flat smoothing (which tends to hide moire patterns).

Lanczos4, Lanczos6, and Sinc4 - remapped pixels receive sharpening which can be useful for scaling down. Lanczos4 provides the least sharpening and Sinc4 the most.