Main, Value and Alpha content
Shape brightness and transparency with independent sources and HDR blends.
Work with three content channels#
Value Blend and Alpha Multiply editing is available in Professional and Advance. Existing channels continue to render when you switch to Basic.
Select a light and open Content channels in Light Properties. Main content is the light's existing image or procedural source. The additional channels start disabled, so existing projects keep their appearance.
| Stage | Purpose |
|---|---|
| Main content | Produces the source color and radiance |
| Value Blend | Changes luminance using an independent source and operation |
| Alpha Multiply | Multiplies coverage using an independent mask |
| Light blend | Combines the result with layers beneath |
Shape brightness independently#
- Expand Value Blend and enable it.
- Choose a procedural source, or choose HDRi File and Import channel image.
- Choose Multiply, Replace, Add, Subtract or Low Pass.
- Adjust brightness, amount, offset, scale and rotation. Procedural sources expose their own content controls.
Value Blend works on luminance and preserves Main content's color ratios where luminance is nonzero. Black content takes on neutral brightness when an operation introduces light. Channel image files are embedded in saved projects, even when their channel is disabled.
Build an image or procedural mask#
- Expand Alpha Multiply and enable it.
- Choose the mask source.
- Choose Luminance × source alpha or Source alpha only.
- For luminance masks, adjust Mask black point and Mask white point. Values below black become transparent; values above white become fully covered. A white point at or below black creates a threshold.
- Adjust mapping independently of Main content. Invert channel reverses source RGB around 1; with Source alpha only, it reverses alpha.
Alpha Multiply combines with the light's existing opacity and Alpha Mask. A disabled channel is neutral. Areas outside the channel's mapped bounds have zero coverage. Value Blend leaves Main content unchanged there; Alpha Multiply masks it out at 100% amount.
Blend modes#
| Blend | Defined behavior |
|---|---|
| Normal | Alpha-over composition of linear radiance |
| Low Pass | Caps destination luminance at source luminance while preserving destination color ratios |
| Amplify | Multiplies destination RGB by 1 + source RGB; black is neutral |
| Color | Transfers source color while preserving destination luminance |
| Hue | Transfers HSV hue while preserving destination saturation and luminance |
| Saturation | Transfers HSV saturation while preserving destination hue and luminance |
Invert blend changes Low Pass into a minimum-luminance operation and Amplify into division by 1 + source. Add, Lighten, Multiply, Darken, Subtract and Difference remain available. The new modes have explicit HDR definitions; no exact competitor-rendering equivalence is claimed.
Use Composites for a reusable local stack, or Export HDRi for alpha and precision choices.
Use the troubleshooting guide to check the common causes and prepare a useful issue report.
Troubleshooting