Auto Levels

Overview

When noise or a height map is clustered around mid-gray, this correction makes the whole image crisp with a single node. To set the range manually, use Levels.

Technical details

• Fully transparent pixels are excluded from both range calculation and correction.
• If every pixel has the same value (a zero-width range), the image passes through.
• clip_percent guards against outliers so a few blown highlights or crushed shadows do not determine the range.

Usage tips

• When noise or a height map looks flat, insert this node before spending time on parameters. It provides a more stable input for gradient_map or threshold.
• Use strength to blend the effect (0.5 expands the range halfway). Reduce it if the full effect looks unnatural.
• clip_percent (1% by default) is insurance against a few extreme pixels. It prevents a single highlight from keeping the rest of the range compressed.

Common pitfalls

• Brightness varies between variants: automatic correction depends on the input distribution, so every seed can use a different reference when batch-producing. For batch work, fixed values in manual levels produce more consistent results.
• Nothing changes: the image already uses the full range, or every pixel has the same value and passes through. Use a manual adjustment such as tone_curve if you still need a change.

Examples

1. Normalize noise: Noise → Auto Levels expands mid-heavy noise to the full range before sending it to Gradient Map.
2. Adjust a height map: normalize the output from Height From Image to strengthen the shading from Quick Shade.

Related nodes

• levels — the manual-range version, which is more stable for batch production
• histogram_scan — when you want to inspect the distribution itself
• gradient_map / threshold — the go-to destinations after normalization