Metrics for Evaluating Image Denoising and SAR Image Despeckling Performance

When evaluating image denoising and SAR image despeckling performance, several quantitative metrics can be employed to assess effectiveness. Key indicators include Peak Signal-to-Noise Ratio (PSNR), Signal-to-Noise Ratio (SNR), and Equivalent Number of Looks (ENL). These metrics provide objective measurements to understand the performance of image processing algorithms and evaluate their capability in reducing noise and speckle artifacts.

PSNR is commonly calculated using the mean squared error between original and processed images, typically implemented with logarithmic scaling to handle wide dynamic ranges. SNR measures the ratio between signal power and noise power, requiring proper separation of signal and noise components. ENL is particularly important for SAR images, computed by analyzing homogeneous regions to estimate speckle reduction effectiveness through statistical variance calculations.

In code implementations, these metrics often involve matrix operations for difference calculations, statistical functions for mean and variance computations, and logarithmic transformations for decibel-scale results. Proper normalization and region selection are crucial for accurate metric calculations, especially for ENL which requires identifying homogeneous areas in SAR imagery.