Ultimatte PFG ( Processed Foreground) Node

The Ultimatte PFG (Processed Foreground) node enables you to create and output a clean, processed foreground image: that is, an image of the foreground subject with all flare removed, the backing area suppressed to black, and the Ultimatte matte attached as the alpha channel. You will then be able to composite this image using one of the Chalice composite nodes.

Tip:
Before you use the Ultimatte PFG node, you should first use the Ultimatte CSC node to correct any flaws in the backing, or screen area. Screen correction is a critical step in the process of producing high-quality mattes.
Also, if you plan to use the Ultimatte GK node, you should do so prior to processing the image with the Ultimatte PFG node.

Matte density values can be adjusted automatically or manually in the Ultimatte PFG node to correct any holes in foreground areas of the matte caused by spill or flare that would result in print-through in the final composite. See "Adjusting Matte Density " for a description of how Ultimatte performs this adjustment. The Ultimatte PFG node also provides flare controls that you can use to remove discoloration caused by spill from foreground objects.

The Ultimatte PFG node accepts two inputs: the three-channel (RGB) foreground image and an optional one-channel garbage matte. The garbage matte can be used to extend the backing in cases where the bluescreen was not large enough to fill the frame or to hide lighting equipment and other unwanted elements in the shot.

You can specify whether the node will output only the matte channel, only the processed foreground, or all four (RGBA) channels.

Using Ultimatte PFG

Step 1: Pick a Backing Color

Start by opening the PFG work monitor and clicking on a pixel in the backing area. Ultimatte Intelligence will use the backing color values as a reference for setting color logic and generating matte data. See "How Ultimatte Generates Matte Data " for more information.

If the backing is a homogenous field of color (blue, green, or red), you can select any pixel in the backing that is totally unobstructed by shadows. If it is not, use an Ultimatte CSC node to correct the backing areas before using PFG. Refer to the introduction, "The Ultimatte Nodes ," for more information about when and in what order to use each Ultimatte node.

Step 2: Examine the Matte

Next switch from RGB to Alpha channel display in the work monitor to view the matte channel. Unlike the Ultimatte CSC and GK nodes, which display an inverted matte, the Ultimatte PFG node displays a matte channel where transparent (backing) areas appear black and opaque (foreground) areas appear white. This display represents the alpha channel that the node will output. Any holes in the matte will appear as gray or black areas within white foreground objects.

Step 3: Adjust Matte Density

Fix any matte density problems caused by spill to prevent print-through. Click on one of the gray or black pixels in the foreground and then click the Intelligence: Fix White Matte button. Ultimatte will adjust certain Matte Control parameters for you. Alternatively, you can adjust matte values manually by resetting the parameters on the Matte Controls tab.

The Intelligence: Fix Black Matte button is used the same way when you need to correction imperfections in the backing areas.

Step 4: Correct Discoloration

After you are satisfied with the matte density values, you can use the Flare Controls to correct discoloration, especially of magentas, yellows, and browns, that can be caused by spills and flares. Using an A/B wipe, compare the composited image with the original foreground image to identify these problem areas.

Note:
For the best result, be sure to refer to the Matte Controls and Flare Controls tab descriptions in the Parameters section. Adjusting any of these parameters too dramatically can adversely affect the realism of your composite.

PFG Parameter Tab

Work Monitor / At Resolution

First, select a display resolution for the work monitor from the At Resolution popup menu. Then click the plus icon to display the work monitor for this node. In RGB display mode, you can select a pixel for the Backing Color parameter by clicking on it. In Alpha display mode, you can click on areas that represent holes in the matte that you want Ultimatte Intelligence to fix for you.

Output

The Output popup menu enables you to specify which channels the node will output:

  • All Channels (RGBA) -- the default
  • Matte Channel only (Alpha)
  • Processed Foreground only (RGB)

Color Logic

The Color Logic popup menu displays the processing logic selected by Ultimatte PFG, based on the Backing Color parameter value: Blue Logic (for an image shot against a bluescreen); Green Logic (for a green screen shot), or Red Logic (for red screen).

Backing Color

The Backing Color parameter displays the RGB values of the backing color that you have selected by clicking on an appropriate pixel in the PFG work monitor. You can also key in RGB values for this parameter.

Invert Matte (Checkbox)

Click this checkbox to invert matte values, so that transparent (black) areas become opaque (white) and vice versa.

Reset Parameters to Default Values

Click this button to reset all of the parameters on the Matte Controls tab and Flare Controls tab to their default values, whether these parameters have been adjusted manually or by clicking the "Intelligence: Fix" buttons on the Matte Controls tab.

This will not affect the Backing Color parameter values. (To reset all node parameter values to their default settings, select the "Defaults" option from the node's Presets menu.)

Matte Controls Parameter Tab

The Matte Controls parameter tab enables you to apply programmed intelligence to adjust matte levels (by using the "Intelligence: Fix" buttons) and to manually assign parameter values. Be sure to display the Alpha channel in the work monitor before using the Matte Controls.

You set each parameter by keying a value in the range of 0-100 into the associated data entry field or by using the mouse to set the tuner, if available, to the desired value.

Matte Density & Black Gloss

The Matte Density and Black Gloss parameters enable you to adjust matte density values to eliminate print-through, which occurs when pixels in a foreground object are interpreted as being part of the backing.

Both parameters function by minimizing patches of gray or black within the white foreground objects of the matte. If you set either parameter too high, however, the result may include hard, dark edges around foreground objects and darkening of shadows and backing areas.

Start by using Ultimatte Intelligence (the "Fix White Matte" button). If further adjustment is needed, adjust Matte Density and Black Gloss interactively: increasing Black Gloss may allow Matte Density to be set lower. Readjust both parameters to be as low as possible while still ameliorating the problem.

Tip:
The Black Gloss 2 and RGB Density parameters, which operate on the RGB channels rather than the matte, may help to minimize edge problems caused by Matte Density and Black Gloss.

Matte Density

To control print-through in bright foreground objects, use Matte Density. This situation may be caused by flare or spill, or when a foreground color is too close to the backing color (a blue-eyed actor against a bluescreen, e.g.).

Note:
Matte Density will eliminate print-through problems caused by spill. However, to correct the discoloration spill causes, use the Flare Controls. (The Matte Controls should be adjusted before the Flare Controls.)

The Matte Density default value is 50.

Black Gloss

To control print-through in black glossy or dark foreground objects, use Black Gloss. This situation can be caused when a black glossy object is reflecting color from the backing and is interpreted as being a dark area of the backing. The Black Gloss default value is 0.

Black Gloss 2

The Black Gloss 2 parameter enables you to stop print-through on foreground objects that suffer from excessive spillage from the backing. Unlike Black Gloss, this parameter adjusts RGB values instead of the matte.

The default value is 0. Setting this parameter too high may alter the color of objects in the foreground.

RGB Density

The RGB Density parameter enables you to adjust RGB values to reduce hard, dark edges from objects with strong red (skin tones), green (flora), or blue components. Unlike Matte Density, this parameter adjusts RGB values instead of the matte.

If you set one of the RGB Density values too low, the result may be print-through in foreground objects of the respective color. (For example, a low blue value may result in print-through in blue foreground objects.) In that case, the Matte Density control may need to be readjusted. The default value is 100 for all three component colors.

Clean Up

The Clean Up parameter enables you to eliminate fine imperfections in the backing. However, it can also eliminate subtle details of the foreground such as strands of hair, smoke, shadows, reflections, etc. and ruin the realism of the composite.

Start by using Ultimatte Intelligence (the "Fix Black Matte" button) to set the values for this parameter and Clean Up Balance. If necessary, you can make further adjustments manually. Use Clean Up and Clean Up Balance interactively, and set Clean Up as low as possible; a compromise setting can usually be found. The Clean Up default value is 0.

Clean Up Balance

The Clean Up Balance parameter enables you to assign the degree of influence that the Clean Up parameter has on the foreground relative to the backing area of the image.

The Clean Up Balance default value is 50, which specifies that the Clean Up parameter will affect the foreground and backing equally. Try adjusting this parameter when the Clean Up parameter darkens edges or makes them glow.

Level Balance

The Level Balance parameter will help you even out imperfections or textures in the backing that are noticeable in the composite.

Increasing this parameter will not brighten the background, but it will increase the level in the shadows and transparent areas of the composited image. On occasion, lowering this parameter will result in an enhancement to the fine edge detail in foreground objects.

The default value is 50.

Shadow Noise

The Shadow Noise parameter enables you to reduce noise in shadows and glare areas.

The default value is 50.

RGB Veil

If there are slight variations in color in the backing area, when Ultimatte suppresses the backing color to black a residue of the backing color may remain in some areas. This veil of color can discolor the background image in the composite.

The RGB Veil parameter enables you to adjust the RGB color components in the backing area to suppress this residue. Decreasing these values will remove veiling from the backing area, but may cause dark edges around foreground objects. Increasing the values will add a colorized tint or haze over the background.

The default value is 50 for all three component colors.

Note:
If possible, you should use the Ultimatte CSC node to even the backing area before the image is input to the PFG node.

" Intelligence: Fix" Buttons

When you click one of the Intelligence: Fix buttons, Ultimatte Intelligence will automatically adjust the appropriate Matte Controls parameters.

This adjustment is based on the sample pixel value that you select by clicking on an imperfection displayed in the Alpha channel of the work monitor.

Fix White Matte (Fix Subject)

Intelligence: Fix White Matte is used to eliminate print-through in foreground objects. Click on a gray or black pixel in a foreground object and then click the Fix White Matte button. Ultimatte will adjust the Matte Density and/or Black Gloss parameter values based on the value of the pixel you selected.

Fix Black Matte (Fix Backing)

Intelligence: Fix Black Matte is used to eliminate imperfections in the backing area. Click on a gray or white pixel in a backing area and then click the Fix Black Matte button. Ultimatte will adjust the Clean Up parameter values based on the value of the pixel you selected.

Flare Controls Parameter Tab

The Flare Controls parameter tab enables you to correct the discoloration of foreground objects caused by spills and flares.

During shooting, light reflecting from the backing may "spill" onto the foreground subject, causing discoloration and print-through. This color contamination of the foreground can also occur from reflections within the camera lens, or lens "flare."

Note:
To correct the matte density problems (print-through) caused by spills and flares, use the Matte Controls first. Then use the Flare Controls to correct the discoloration.

How Flare Suppression Works

Ultimatte spill/flare suppression works by analyzing the color components of each foreground pixel. Using blue backing as an example (this suppression works similarly for green and red backings), for most colors in nature, if the blue component exceeds green, it does so by less than green exceeds red. This is true even for many natural pastel shades of blue. The exceptions are deep blues, which have already been suppressed as part of the backing, and magentas.

Ultimatte assumes, therefore, that any time the blue component in a color exceeds green by more than green exceeds red, it is because of blue spill contaminating the color. Ultimatte adjusts the values so that blue only exceeds green by the amount green exceeds red (or by holding blue to the level of green if green is equal to or less than red), any unnatural bluish tints will be removed while natural blues will be unaffected.

As mentioned before, Ultimatte may interpret foreground objects with a magenta tint as being contaminated by blue spill and change shades of magenta to shades of red. In this case, you will need to adjust the Gate controls to compensate.

Another problem may arise with some shades of yellow and brown that are contaminated by blue spill. The blue component should be less than green, but Ultimatte suppression will allow blue to equal green, slightly desaturating these colors. In this case, you will need to adjust the Black or Gray Balance controls.

Each of the Flare Control parameters can be set by keying in a numerical value in the range of 0-100 or by using the mouse to set the tuner to the desired value.

Balance Parameters

The Balance parameters enable you to make foreground colors warmer or cooler by overriding the spill/flare suppression logic which ensures that whites in the foreground have equal amounts of red, green, and blue:

  • Use the White Balance parameter for light colors.
  • Use the Gray Balance parameter for midrange colors.
  • Use the Black Balance parameter for dark colors.

The default value is 50 for all three parameters. Set the parameter by eye while viewing the composited image.

White Balance

Use the White Balance parameter to adjust light foreground colors with minimal effect on darker colors. It can make foreground whites match the cool/warm tint of background whites.

For example, flare suppression logic can cause blond hair, shot against blue backing, to look white around the edges. Adjusting White Balance can restore a warmer, more natural color to the hair without significantly affecting other colors.

Black Balance

Use the Black Balance parameter to adjust dark foreground colors with minimal effect on lighter colors. It can make foreground blacks match the cool/warm tint of background blacks.

For example, adjusting Black Balance can eliminate flare from black and brown hair (and some blond hair) with minimal effect on light colors. You can also compensate for the slight desaturation of some colors that the suppression logic can cause.

Gray Balance

Use the Gray Balance parameter to adjust midrange foreground colors with minimal effect on lighter and darker colors. It can make foreground grays match the cool/warm tint of background grays.

For example, used in conjunction with Black Balance, Gray Balance can help compensate for the desaturation of some colors.

Gate Parameters

The Gate parameters, Gate 1 & 3 and Gate 2, enable you to adjust specific color ranges, depending on the type of logic (blue, green, or red) assigned to the Color Logic parameter on the PFG parameter tab. The default value for Gate 1 & 3 is 100; the default value for Gate 2 is 0.

Gate 1 & 3

The following table illustrates the spill suppression effect of the Gate 1&3 parameter on various color families:

Blue Logic Green Logic Red Logic
Blue-Cyan-Green Green-Cyan-Blue Red-Yellow-Green
100 Blue unaffected Green unaffected Red unaffected
50 Blue turns Cyan Green turns Cyan Red turns Yellow
0 Cyan turns Green Cyan turns Blue Yellow turns Green

For example, if Blue Logic is specified for the Color Logic parameter, compare the original foreground and the composite. Look to see if any cyan objects have turned blue, or green objects cyan. If so, you can probably use the Gate 1&3 parameter to remove the excess blue.

Gate 2

The following table illustrates the spill suppression effect of the Gate 2 parameter on various color families:

Blue Logic Green Logic Red Logic
Magenta-Red Yellow-Red Magenta-Blue
0 Magenta turns Red Yellow turns Red Magenta turns Blue
100 Magenta unaffected Yellow unaffected Magenta unaffected

For example, if Blue Logic is specified for the Color Logic parameter, compare the original foreground and the composite. Look to see if any magenta or pink objects have turned red. If so, you can probably use the Gate 2 parameter to restore the true blue component.

Note:
The default value for Gate 2 depends on the color logic. For Green Logic, the Gate 2 parameter will be automatically be set to a value of 50. This will prevent hair and skin tones from losing their green component and taking on a purple or red cast.



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