Everything you need to know about Histogram Stretch
Histogram Stretch analyzes your image to find its actual darkest and brightest pixels, then stretches that range to span the full 0–255 spectrum. This automatically maximizes contrast and tonal range, especially useful for flat or low-contrast images.
Parameters
- Stretch Amount
Controls how aggressively the histogram is stretched. At 0%, no change is applied. At 100%, the full suggested range is mapped to span the complete black-to-white spectrum. Intermediate values apply partial stretching for more subtle corrections.
How It Works
The filter automatically detects the minimum and maximum brightness values in your image (shown as "Suggested range"). It then remaps these values so the darkest pixels become pure black (0) and the brightest become pure white (255), stretching everything in between proportionally.
Suggested Range Display
The dialog shows the detected input range (e.g., "Suggested range: 23 – 241"). If this range is close to 0–255, your image already uses the full tonal spectrum and stretching will have minimal effect. A narrow range (e.g., 45–180) indicates a low-contrast image that will benefit significantly from stretching.
Tips
- Start at 100% and reduce if the result looks too harsh
- Works best on images that don't use the full brightness range
- Use 50–70% for a more subtle, natural-looking enhancement
- Compare with Auto Levels and Auto Contrast for similar but slightly different results