Bloom

Applies bloom in three stages: threshold extraction, separable Gaussian blur, additive compositing. The extraction is a simple threshold with no soft knee, max(color - Threshold, 0), and is built on the assumption of HDR input (such as the output of Render), but it also works with LDR images. The blur is done at half resolution.

• Threshold — default 1. Negative values are treated as 0 (Threshold input / thresholdInput)
• Intensity — the amount added. Default 0.8. Negative values are treated as 0 (Intensity input / intensityInput)
• Iterations — the number of blur round trips. Clamped to 1-6, and floats are rounded to an integer. Default 3 (Iterations input / radiusInput)

Iterations does not just increase the number of passes, it also increases the spread of the blur. On the i-th round trip the sample spacing becomes 1 + i texels, so the higher the count, the farther the light reaches.

Threshold (default 1) is a value that assumes HDR. If you apply it at its default to LDR material (maximum 1.0), the extraction result can come out at nearly 0 and nothing glows. In that case, lower Threshold.

The output alpha is always fixed at 1. If the input is removed, the output is cleared to black.

The output supports HDR, and the resolution is the same as the input.