On-Orbit Modulation Transfer Function Estimation Based on the Refined Image Kernel

Area of Science:

• Remote Sensing
• Optical Imaging
• Image Quality Assessment

Background:

• Traditional on-orbit modulation transfer function (MTF) measurement methods rely on external targets, limiting their applicability.
• Accurate on-orbit MTF measurement is crucial for assessing satellite optical imaging quality and stability.

Purpose of the Study:

• To develop a novel, efficient, and accurate on-orbit MTF measurement method for remote sensing imagers.
• To overcome the limitations of traditional MTF measurement techniques dependent on external features.

Main Methods:

• A refined image kernel (RIK) is estimated from remote sensing sub-images using iterative support detection (ISD) and central pixel energy concentration (EC).
• Modulation transfer function (MTF) curves are calculated by interpolating the RIK and applying Fourier transform.
• The final MTF is determined by averaging MTFs at Nyquist frequency from each RIK.

Main Results:

• The proposed method demonstrated a maximum error of less than 7% compared to the ISO12233 edge method.
• Relative error did not exceed 5% for image signal-to-noise ratio (SNR) above 20dB.
• On-orbit measurements using Jilin-1 satellite data showed a maximum error of less than 2% compared to the ISO12233 edge method.

Conclusions:

• The refined image kernel (RIK) method provides highly accurate and robust on-orbit MTF measurements.
• This technique significantly increases the efficiency of on-orbit MTF assessment for remote sensing imagers.
• The method serves as a valuable reference for high-frequency monitoring of satellite on-orbit stability and optical imaging quality.