Normalization (division) versus subtraction of digitized images.

Area of Science:

• Medical Imaging
• Digital Image Processing

Background:

• Noise propagation in digital images can affect diagnostic accuracy.
• Algebraic manipulations are common techniques in image processing.

Purpose of the Study:

• To investigate noise propagation in digitized images created by algebraic manipulation.
• To compare the signal-to-noise ratio (SNR) enhancement of different algebraic methods.

Main Methods:

• Evaluated logarithmic subtraction, linear subtraction, and division of two images.
• Considered two extreme video-fluoroscope system behaviors.
• Calculated SNR and established a figure of merit for each method.

Main Results:

• The figure of merit for the division process was consistently greater than unity compared to subtraction methods.
• Specific figures of merit were provided for varying iodine concentrations (5, 20, 300 mg/cm³).

Conclusions:

• Image division is an advantageous signal-to-noise enhancer.
• This method is suitable for applications where a direct quantitative relationship between image contrast and photon flux is not critical.