SNR If the SNR is for frame averages

SNR • If the SNR is ____ for ____ frame averages, what will be the SNR for _____ frame averages if N is independent for each frame. • S= Signal • N= Noise • SNR = Signal to Noise Ratio

Brightness and Contrast • Given the following histogram ---, how would you adjust the brightness and contrast to ‘improve’ the image, where improvement consists of ____

Gamma • Given the following distortion of the image levels, what gamma would you use to correct to a realistic image view? Assume that the equipment is properly calibrated except for the distortion shown.

Brightness/Contrast • How does a change in brightness/contrast monitor controls affect the monitor display of image levels? • How does a change in image brightness/contrast affect the histogram and the monitor display of image levels?

Image Generation • What is the basic concept behind – ultrsound imaging – x-ray tomography – magnetic resonance imaging – nuclear imaging • PET and radioisotopes

Image Generation continued • What is the purpose of a phantom? • Define: – image modulation transfer function – Poisson noise – surround induced visual stress – HSL and RGB and CMYK

Definitions • What is meant by – pincushion defect – barrel defect – vignetting – spectral response • for eye • for camera

Image filtering • An accurate mathematical description for a imaging convolution filter is: • _________________ • Define variables used in the description

Histogram adjustment • Given a histogram, what happens to the displayed image levels as the brightness, contrast and gamma are changed

Pseudo Colors • How is a lookup table used to produce an image with pseudocolors? • What would be a best choice of size for an adjustable lookup table and why?

Color planes • What is the difference (in words) between RGB and HSL?

Stereo • What is the difference between the conventional usage of the terms stereology and stereoscopy?

Grids • What types of information can be obtained from stereology by superimposing a grid on an image?

Reconstruction • What is the numerical result in the example at the top of p 116 when the multiplicative ART in eqn 7. 23 is applied. • What is the (clear) definition in words for each of the variables in Figure 7. 8 • If f(x, y)=f(x)f(y), show that eqn 7. 28 reduces to F(u)F(v).

JPEG • JPEG uses the FFT as part of the algorithm to compress an image. • What specifically is the saving in stored bytes with the FFT is used? • Under what conditions will the result of the FFT be the poorest image quality.

Median Filter • What does a median filter do, and what are its relative advantages?

Perceived levels • How many gray scale levels can a person typically perceive? • How many color shades can a person typically perceive?

Rolling Ball/Top Hat • When would you use a rolling ball or top hat filter? Pick one as an example, describe its properties and what it can do, and explain when you would use it. Bear in mind that the filter can be used on either an image or on its negative.

Definitions • • • Affine Transformation Bilinear interpolation Morphing Laplacian operator as a convolution filter FFT masking. Why? Boolean image operations. What are they?

Definitions • • Erode dilate open close skeletonize euclidean distance map blob in IP sense

Definitions • What is accuracy? • What is precision? • What is an example when operator error affects the clinical interpretation of an image. Explain in terms of accuracy and precision.

Definitions • What is image classification? • How does image classification help stereology?

Reconstruction • What are the mathematical properties of a delta function when used in an integral. Show graphically by example. • If an image is rotated 25 o, then what is the rotation of the 2 -D transform of the image.

FFT Reconstruction • What are the underlying principles for the four methods discussed for CT image reconstruction? • What are the underlying principles for mri image reconstruction?