Magnification in CS: Pre & Post Processing Terms

preprocessing

the manipulation of image date before storage in the scan converter

preprocessing alters

the image data forever and cannot be reversed or undone

postprocessing

the manipulation of image data after storage in the scan converter

postprocessing changes can be

reversed which will restore the initial numerical values of the image data

preprocessing

time gain compensation

log compression

write magnification

persistence

spatial compounding

edge enhancement

fill in interpolation

postprocessing

any change after freeze time

black/white inversion

read magnification

contrast variation

3-D rendering

magnification

improve visualization of the anatomic detail by enlarging a portion of an image to fill the entire screen

two forms of magnification

read

write

read magnificaiton

occurs after the image data is stored in the scan converter

read magnification consists of 3 steps

the ultrasound system scans the anatomy

the image is converted from analog to digits and is stored in the scan converter

the system reads and displays only the original data that pertains to the region of interest

read magnification is characterized by

the number of pixels or scan lines in the magnified image is the same as the original image

spatial resolution does not change because the number of pizels in the ROI is unchanged

read magnification can be used

on a frozen image, and is postprocessing

write magnification

applied during data acquisition before storage in the scan converter

write magnification steps

1. Ultrasound system scans and creates image.

2. Image is converted from analog to digital.

3. Sonographer identifies region of interest and system discards all other information.

4. US system rescans area of interest only.

Write magnification is characterized by

1. Image to identify ROI is discarded and new info acquired.

2. Number of pixels/scan lines in ROI image is greater than original image.

3. Increased number of pixels in ROI improves spatial resolution; pixel size unchanged

read magnification

uses old data

postprocessing

larger pixel data

sae number of pixels as in teh original ROI

unchanged spatial resolution

unchanged temporal resolution

write magnification

acquires new data

preprocessing

identical pixel size

more pixels than the original ROI

improved spatial resolution

may improve temporal resolution