Glow

The Glow lets you generate subtle gradations of light in your composition.

The Glow tool has the following parameters:

• Threshold Lets you determine which parts of the image (usually the brightest) you want to apply the glow to. You can base the threshold either on a channel; Red, Green, Blue or Alpha, or Luma, or on a color component of the image (R,G,B or overall luminance). Values that fall above the set threshold will have a glow applied and values that fall below the threshold will be set to black.
• Gain Colors the glow you apply to an image.
• X Radius and Y Radius Applies a blurred edge to the glow. Using the Master slider will apply a blurred edge to both the X and Y radii uniformly. You can also select a single color component or select just the X or Y parameter to apply the blur to by deselecting the Lock button located at the right of the button.
• Output Mode Choose between working with either the composite of the image you are working with or just the glow applied to it. If you select Composite, it applies the blend mode selected.
• Blend Select the blend mode you want to apply to the glow. Select Blend to display available blend modes.

To set the threshold:

1. Do one of the following:
   • Drag the trackball towards the color you want to set as the threshold.
   • Drag any of the red (R), green (G), or blue (B) channel fields to the right to increase, or to the left to decrease the threshold uniformly on all three channels. Alternatively, you can also drag the luminance (L) field to achieve the same result. Select the Reset button to return all values to 0.
   • Select a single channel that you want to modify by deselecting the Lock button to the right of the channel, then increase or decrease the threshold. The other channels are not affected. However, the overall luminance field updates to reflect the change. Select the Reset button to return all values to 0.
   • Type values into the channel fields and press Enter. In the case of modifying all channels uniformly, when values are typed into any field, the other fields update. The luminance field will update regardless of which method is used to modify the values. Select the Reset button to return all values to 0.

To set the gain on a glowed portion of an image:

1. Do one of the following:
   • Drag the trackball towards the color you want to add or decrease gain to.
   • Drag any of the red (R), green (G), or blue (B) channel fields to the right to increase, or to the left to decrease the gain uniformly on all three channels. Alternatively, you can also drag the luminance (L) field to achieve the same result. Select Reset to return all values to 0.
   • Select a single channel that you want to modify by deselecting the Lock button to the right of the channel, then increase or decrease the gain. The other channels are not affected. However, the overall luminance field updates to reflect the change. Select the Reset button to return all values to 0.
   • Type values into the channel fields and press Enter. In the case of modifying all channels uniformly, when values are typed into any field, the other fields update. The luminance field will update regardless of which method is used to modify the values. Select the Reset button to return all values to 0.

To set the X or Y Radius to the edge of a glow:

1. Do one of the following:
   • Drag any of the red (R factor), green (G Factor), or blue (B Factor) channel fields to the right to increase, or to the left to decrease the radius uniformly both the X and Y radii. Alternatively, you can also drag the Master field to achieve the same result on all color factors.
   • Type values into the channel fields and press Enter. To deselect the lock on any parameter, click the Lock button.

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