a specific range of pixel
values.
a specific range of pixel
values.
Nuke’s HSVTool node lets you simultaneously adjust hue, saturation, and value components from a single properties panel. It also features a color replacement tool. The main strength of this node is the precision it offers in limiting corrections to a narrow swath of colors.
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| Adjusting color within a specific range of pixel values. |
Adjusting color within a specific range of pixel values. |
For example, suppose you wanted to add a bit more punch to the waterfront scene by diversifying the rooftop hues. To do so, you could limit the correction to the rooftop’s ochre-colored hues by sampling a few pixels, then shift their values. Because you limited the color range, the surrounding image would be generally unaffected by the shift.
| 1. | Click Color > HSVTool to insert an HSVTool node at the appropriate place in your script. |
| 2. | Connect a Viewer to the output of the HSVTool node so you can see the effect of your changes. |
| 3. | Limit, as appropriate, the range of colors you want subsequent corrections to influence: |
• In the HSVTool properties panel, click the srccolor color swatch. Ctrl/Cmd+click on the Viewer to sample a single color displayed, or Ctrl/Cmd+Shift+drag to sample a range of colors. To sample a single color from the node’s input while viewing its output, Ctrl/Cmd+Alt+click on the Viewer. To sample a region from the input, Ctrl/Cmd+Alt+Shift+drag on the Viewer.
• The Range sliders on Hue, Saturation, and Brightness clamp to the sampled range.
• For any color component, drag on the Range sliders to expand the color range as necessary.
• For any color component, drag on the Range Rolloff slider to fine tune the color range. Doing so, adjusts the amount of falloff allowed past the limits defined by the Range sliders.
| 4. | Make the necessary HSV corrections: |
• For hue corrections, drag on the Rotation slider to input color wheel value between 0 and 360.
• For saturation corrections, drag on the Saturation Adjustment slider to input values between -1 (completely desaturated to some shade of gray) and 1 (completely saturated).
• For value corrections, drag on the Brightness Adjustment slider to input values between -1 (black) and 1 (white).
You can also make color replacements using the srccolor and dstcolor parameters: First sample the color you wish to replace with the srccolor color swath, then sample the color which you wish to use as the replacement with the dstcolor color swath. The color in dstcolor replaces the color in srccolor throughout the image.
Also, keep in mind that the HSVTool node makes an excellent keyer. You can use its Hue, Saturation, and Brightness range sliders to precisely select a range of colors, then use the channel output dropdown at the bottom of the dialog to output this selection as a matte channel. This dropdown lets you specify which color components (hue, saturation, value, etc.) are added to the matte.