Houdini 20.5 Nodes Copernicus nodes

Illegal Pixel Copernicus node

Detects illegal pixels, like NAN and INF, in images.

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Shaders and renderers can generate illegal floating point values every once in a while. This operation detects bad pixels, specifically NAN and INF, and either highlights them or fixes them.

Because the data is missing from that pixel, it can be zeroed out or replaced by blending together surrounding pixels. When zeroing pixels, the entire pixel is zeroed even if only one component is bad (to avoid color shifting).

If pixels are replaced, and only a part of the pixel’s components is bad, only that component will be replaced. If a large block of bad pixels is present, it will attempt to iterate up to 16 times to break down the block. Large blocks will look like blurry spots in the image, so you may want to limit the number of bad pixels to replace.

Note

Bad pixels are only detectable in floating point formats (16 and 32 bit floating point). Integer formats will have already been quantized to a valid (but possibly random) color in the renderer, making them impossible to detect.

Parameters

Illegal Pixel

Illegal Pixels

Illegal pixels can be flagged or fixed. Often, flagging is used to debug the shader, while fixing is used to attempt to continue with the image as-is.

“Fix by Blending Surrounding Pixels”

For small numbers or isolated pixels, this method will work well to fix the image.

“Fix by Zeroing”

This method clears the NANs so that downstream compositing operations behave, but doesn’t do much in the way of visually correcting the image.

“Show by Highlighting”

Shows bad pixels by highlighting them super-red (20,0,0).

“Show by Isolating”

Shows bad pixels by highlighting them and clearing all correct pixels.

Detect

Which type of illegal pixels to find.

“NaN Values”

NaN values only.

“Infinite Values”

Infinite values only.

“NaN and Infinite Values”

Both NaNs and infinite values.

“Custom”

Values according to a custom rule.

Rule

The custom rule to use.

“Less Than”

Flag pixels less than the comparison value.

“Less Than or Equal”

Flag pixels less than or equal to the comparison value.

“Great Than”

Flag pixels greater than the comparison value.

“Greater Than or Equal”

Flag pixels greater than the comparison value.

“Equal”

Flag pixels equal to the comparison value.

Comparison Value

The value to compare pixels to when in Custom detection mode.

Locals

Copernicus nodes