Computes the gradient of an image.
Computes the gradient of the image, which indicates the direction of greatest luminance increase in UV. The map produced looks like a bump map.
The different maps produced by this operation are:
UV Gradient - Computes the UV gradient of the image, which is a 2D vector which points in the direction of greatest luminance increase. The magnitude of the vector is the increase amount. Similar to the results produced by the Bump COP.
Normal Map - Computes a normal map from the gradient. The normal and the gradient are similar: the normal is a normalized 3D vector with the Z component set to 1 and X & Y set to the U & V values of the gradient.
Gradient Magnitude - Computes the gradient magnitude, which appears as a luminance edge-detected image.
Thresholded Magnitude - Computes the gradient magnitude and only accepts values between the low and high threshold values. If normalize is on, the values are mapped from low to high to 0 to 1.
Parameters
| Gradient Type | The channel used to compute the gradient. | ||||||||
| Output | The type of output produced:
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| Low/High Threshold | The low and high thresholds for thresholded magnitude output. | ||||||||
| Normalize | If UV Gradient output is used, this normalizes the gradient’s magnitudes to 1. If Thresholded Magnitude is used, this maps the low to high range to 0 - 1. |
Mask
A mask can be chosen to limit the effect of the operator to areas defined by the mask. The mask can be taken from the mask input (side input) or from the first input itself.
| Effect Amount | If no mask is present, this blends the output with the input by a constant amount (0 = all input, 1 = all output). If a mask is present, this amount multiplies the mask. | ||||||
| Operation Mask | Selects the mask plane to use as a mask from the mask input. The mask can be selected from: A mask can be a component of a plane or an entire plane. If a vector plane is supplied as a mask, its components are multiplied by the images' components. Scalar Mask ('A', 'C.r')
C.r = I.r * M
C.g = I.g * M
C.b = I.b * M
Vector Mask ('C')
C.r = I.r * M.r
C.g = I.g * M.g
C.b = I.b * M.b
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| Resize Mask to Fit Image | If the mask image is a different resolution than the output image, turning on this parameter will scale the mask to the output image’s resolution. If this node is changing constantly, and the mask is not, it is somewhat faster to put a Scale COP down to do the resize for the mask image. Otherwise, the scale will occur every time this node cooks. | ||||||
| Invert Mask | Inverts the mask so that all fully 'masked' portions become unmasked. This saves you from inserting an Invert COP after the node with the mask. |
Scope
| Plane Scope | Specifies the scope for both the RGB components of Color, Alpha, and other planes. The (C)RGBA mask only affects Color components and Alpha. 'C' will toggle all the RGB components. For planes other than Color and Alpha, the plane name (plus component, if applicable) should be specified in the string field. The pulldown menu can be used to select planes or components present in this node. A plane is specified by its name. A component is specified by both its plane and component name. The '*' wildcard may be used to scope all extra planes. Any number of planes or components can be specified, separated by spaces. Examples:
P
N.x N.y
P N Pz
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Frame Scope
| Frame Scope | Allows scoping of specific frames in the frame range. This is in addition to the plane scope (so a plane at a certain frame must be both plane scoped and frame scoped to be modified).
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| Frame Range | For Inside/Outside range, this parameter specifies the subrange of the sequence to scope (or unscope). This can be edited in Timeline viewer mode (Ctrl+2 in viewer). | ||||||||||||
| Frame Dropoff | For Inside/Outside Range, this parameter specifies certain number of frames before and after to slowly ramp up to scoped. The operation will be blended with its input to 'ease in' or 'ease out' the scoping effect over a number of frames. This can be edited in Timeline viewer mode (Ctrl+2 in viewer). | ||||||||||||
| Non-scoped Effect | For unscoped frames, this sets the blend factor between the input and modified images. Normally this is zero (use the input image). By setting this to a non-zero value, you can make unscoped frames be 'slightly' unscoped. The value can vary between 0 (unscoped) and 1 (scoped). | ||||||||||||
| Frame List | The frame list for 'Specific Frames'. Frame numbers should be separated by spaces. | ||||||||||||
| Automatically Adjust for Length Changes | If the sequence range changes, enabling this parameter will adjust the subrange and frame dropoff lengths to fit the new range. |
Local variables
| L | Sequence length |
| S | Start of sequence |
| E | End of sequence |
| IL | Input sequence length |
| SR | Sequence frame rate |
| NP | Number of planes in sequence |
| W,H | Width and height of image |
| I | Image index (0 at start frame) |
| IT | Image time (0 at start frame) |
| AI | Current plane array index |
| PI | Current plane index |
| PC | Num of channels in current plane |
| CXRES | Composite Project X resolution |
| CYRES | Composite Project Y resolution |
| CPIXA | Composite Project pixel aspect ratio |
| CDEPTH | Composite Project raster depth |
| CBP | Composite Project black point |
| CWP | Composite Project white point |