Upload
stephanie-bond
View
228
Download
2
Tags:
Embed Size (px)
Citation preview
Digital Radiographic Digital Radiographic Image Processing and Image Processing and
ManipulationManipulationChapter 7
We’ve learned how images are We’ve learned how images are captured….nowcaptured….now
What happens in the reader (CR) pre processing?
How is the image constructed digitally?
LET’S FIND OUT!!!
PRE-PROCESSINGPRE-PROCESSING
THE READER IS TO BE INFORMED AS TO WHAT EXAM WILL BE PROCESSED.
So when you “flash” the cassette, or scan with a bar code reader or in DR, choose the patient and the examination and the views that are to be done
HISTOGRAMHISTOGRAMGraphical representation of optimal densities collected by exposure data recognition .
Exposure data recognition finds the collimated edges , disregards the scatter outside of these edges
Searches for anatomy
This area is the source of exposure data indicator
CR sampling, CR sampling, Carter pg 110 and Carter pg 110 and Page 492 BushongPage 492 Bushong
Notice the collimated area of the lungs in A and find the associated area in B on histogram and C on the response cure. Do the same for the black areas around the chest.
High energy=less frequency of the same density = narrower histogram
Low energy=more frequencies of the same density= wider histogram
NYQUIST THEOREMNYQUIST THEOREM
When sampling(converting from analog to digital) a signal, the sampling frequency must be greater than the bandwidth of the input signal
http://images.google.com/imgres?imgurl=http://www.cs.cf.ac.uk/Dave/Multimedia/nyquist.gif&imgrefurl=http://www.cs.cf.ac.uk/Dave/Multimedia/node149.html&h=420&w=529&sz=6&hl=en&start=10&um=1&tbnid=zyDOLJNUH6mM8M:&tbnh=105&tbnw=132&prev=/images%3Fq%3Dnyquist%
SKIPPING LUT,EXPOSURE SKIPPING LUT,EXPOSURE LATITUDE, MTF, QC workstation LATITUDE, MTF, QC workstation functions FOR NOW….NEXT functions FOR NOW….NEXT SEMESTERSEMESTER
However let’s discuss image manipulation
Window
Level
Stitching