Auto Gamma

Feature Auto Gamma
Feature

Auto Gamma

August 16, 2026

✨ A Complete Guide to the Auto Gamma Tool

PhenoCapture’s Auto Gamma tool provides an intelligent solution for images that suffer from over-exposed or under-exposed midtones. By analyzing the overall average brightness of your image, the algorithm automatically calculates a customized, non-linear gamma curve to gently push the midtones toward a perfect, balanced exposure (0.5 luminance). Just like our other auto-adjustment tools, it scales the RGB channels proportionally to ensure your original color balance remains completely intact.

💡 Key Features

  • Non-Linear Midtone Correction: Instead of simply stretching the black and white points, Auto Gamma calculates the average brightness of your pixels and generates a customized mathematical curve (Math.Pow). This non-linear adjustment smoothly brightens dark shadows or darkens washed-out highlights without clipping the extreme blacks and whites.
  • Color-Preserving Scaling: To prevent unnatural color shifting, the tool maps the new gamma-corrected grayscale value and calculates a proportional ratio. This exact ratio is applied to the original Red, Green, and Blue values—restoring the perfect midtone exposure while perfectly preserving the true colors of your sample!
  • Smart Regional Masking: Need to correct the exposure on just one specific shadowy object? Draw a selection boundary! If a mask is active, the Auto Gamma algorithm will exclusively analyze the average brightness of that specific region and correct it, while leaving the rest of your image completely untouched.
  • Multi-Core Parallel Processing: Built for maximum efficiency. The tool leverages advanced parallel processing (TPL) to divide the heavy pixel-by-pixel mathematical scaling across your computer’s CPU cores, ensuring blazing-fast execution even on high-resolution images.
  • Smooth Progress Tracking: For larger files, the engine intelligently reports its progress in ~10% intervals. This prevents UI freezing and keeps your workspace responsive while the algorithm crunches the data in the background.
  • Seamless Undo Integration: Connected directly to PhenoCapture’s built-in undo engine. You can safely experiment with the Auto Gamma adjustment and instantly revert to the original state if needed!

🛠️ How to Use the Auto Gamma Tool

Step 1: Prepare Your Image and Mask (Optional)

Ensure your image is loaded into the main workspace. If you want to restrict the midtone optimization to a specific under- or over-exposed area, use the advanced selection tools to draw your mask boundary. Otherwise, the tool will process the entire image.

Step 2: Apply Auto Gamma

Navigate to the menu and click on Auto Gamma.

Step 3: Let the Engine Work

The software will instantly analyze the average grayscale luminance of your image (or masked area), calculate the optimal non-linear gamma curve, and proportionally scale the RGB values. You can monitor the progress bar for larger files. Once complete, your beautifully balanced image will appear in the workspace immediately. If you wish to compare it with the original, just use your standard Undo shortcut!