Ultrasound Physics

Preprocessing and Post Processing

Preprocessing: Preprocessing is before the image has been formed. All signal conditioning processes belong to preprocessing category. Before convert echo lines to a gray scale image, the echo line needs go through amplification, filtering, time gain control, automatic gain control, envelope detection, noise floor rejection, dynamic range compression.
Post Processing: Post Processing is after the image formation. Following processes may apply:

Freeze frame: real time image usually go through a pipe line memory before display, once user press ‘Freeze’ button, the previous image can be browsed through a trackball or a cursor. Frame freeze function is almost available in all the ultrasound imaging system.
Black/white inversion: Press this button the gray scale will inverse, it is good to generate negatives.
Contrast variation: Image should be able to change contrast, sharper or smoother.
Frame averaging: Several frames may be averaged before display to remove spatial noise.
Edge enhancement: Use edge enhancement, object profile will become more distinct.