M2 L1 Histograms and automatic rescaling

what is a histogram

graph of values that shows a radiograph

what is LUT stand for

look up table

what is LUt

the ideal histogram for a projection

what does the x axis represent in LUT

amount of exposure

what does the y axis represent in LUT

number o fpixels for each grey value

what is Smin

the brightest value

what is Savg

average between Smin and Smax, used to calculate EI

what is Smax

the darkest value

what is a type 1 histogram

spike in the far right, there is anatomy but aswell as spots that are not covered.

what type of histogram is this

type 1

what type of histogram is this

type 2

what type of histogram is this

type 3

what is a type 2 histogram

the radiograph is full of anatomy

what is type 3 histogram

there is a radiopaque object in the radiograph

explain how a LUT works

1. select image on control panel

2. take image

3. image is compared to LUT

4. LUT changes Smin and Smax to have ideal contrast

segmentation

determining anatomy

what does CR system use fro data recognition

segmentation

exposure field recogniton

defining borders

what is exposure field recognition determined by in CR

segmentation

what is automatic rescaling

computer tries to fix exposure errors to match LUT

how does automatic rescaling work for contrast

computer will widen or narrow the histogram to increase or decrease contrast

high or low contrast

high contrast

does widening or narrowing the histogram change the number of pixels in each value

no