Digital Image Preprocessing & Processing

Pre-processing #2?

Re-mapping of input data from image to present pixel values to produce brightness & gray scale in the displayed output i

The Q values come from a permanent ____ _____.

Histogram analysis failure is less common w/ CR then DR.

The distinction between pre-processing & post-processing is their timing rather than their purpose.

What's caused by failure of individual dexels can be filled in data.

Smin is located on the right and Smax on the left.

"_____" of data from the acquired image to be used for rescaling are designated as S values.

Rescaling can align image brightness partially.

What's a sub-matrix that is passed over the larger image matrix executing some mathematical function?

What is used for the dynamic range?

DR ______ the detector before each exposure, CR uses partitioned _______ _______

What is the Qmax?

The pixel value/pixel count is termed: Histogram.

What corrects the brightness, & partially corrects the gray scale for each image?

What type of histogram has no tail, & has no background density?

White on a histogram is located on which side?

Rescaling is simply a process of algebraically "_______" incoming data.

When the body portion of the curve is shallow, it indicates a _____ gray scale output image.

The "spike" portion represents the background density of the image, this is referred to as the _______ of the graph.

A histogram for a body part covering the entire IR, so that there is no background density, what does it not seek for?

DR systems typically under go more pre-processing than CR systems.

Dead detector elements can result from failure of what?

What needs to be eliminated and excluded from histogram calculations?

Electronic Response & Gain Offsets are only used in DR.

Rescaling is the step that "automatically" corrects brightness for each image.

What shows up as black on a histogram after Smax?

We always match the Q range to the S range.

The computer scans the data ______ from both the left & right ends of the histogram.

You can say bin/computer files can be classified as "color values"

Black on a histogram is located on which side?

Current flowing through the system, when no exposure has taken place

Light guide variations is only used in DR.

The full range of acquired image data is used, ranging from Smin to Smax

All adjustments made after acquisition corrections have been made, targeted at refinement of the image.

Saverage is the organs/grays.

Accumilated background exposure, when no exposure has physically taken place is called?

What is the dynamic range that is far beyond the discernment of the human eye?

Q2 will always output at a gray level or pixel value of 512.

Individual detector elements are manufactured w/ slight variations in their sensitivity to xrays or light.

What shows up as white on a histogram before Smin?

What has a 5 quad pixel value?

Based on a simple scale of brightness (or density), usually from black to white.

Another word for Saverage

What is due to electronic & optical flaws in the image receptor & reader?

Rescaling can align image gray scale perfectly.

Histogram for body parts that do not cover entire IR, leaving some areas of raw radiation background called?

We use _ values when referring to processed data that has already been rescaled.

The computer can align the average brightness of the image.

What is the "ideal" histogram?

You recognize change in the image through landmarks, & recognize landmarks with the histogram.

What means that regardless of input values, the output values are always the same?

What can affect segmentation?

Averaging data from the previous 50 procedures performed for the specific anatomy, is called a ______ histogram.

What can compensate for moderate cases of pixel drop-out by interpolating & filling these pixels?

Computer algorithm first selects a particular range of densities from the image to operate on, called the ___ ____ ____.

What scans across the receptor plate row by row, to determine the # & orientation of views taken?

_ values are the finalized "for presentation" pixel values after all post-processing operations are complete.

What plots output densities in the final processed image against the input detector values that they were generated from

The most common type of histograms are for

What test uses low exposure w/ no object, comparing 4 corners & center of field.

Pre-processing makes _______

To make corrections to the raw image, to make it perfect. Conventional radiograph, everything is prepared.

To rescale an image, a computer algorithm does what to the incoming S values to permanent Q values?

What software recognizes each collimated border of an exposed field by the sudden dramatic change in density?

The 4 variations in field uniformity is dexel dropouts, dark noise, dark current, & dead pixels.

We use _ value when referring to data that has not yet been rescaled (incoming data)

To identify landmarks in the data, use ____ ____ that only begin storing values when a certain # of pixels is reached.

Post-processing makes _________

Bright & densities must be eliminated before histogram makes calculations.

A _____ digital image directly from the image receptor appears as "washed-out," w/ low contrast.

Pre-processing #3?

Average density within the anatomy, used to calculate the exposure indicator.

Mammography/Barium: must have _____ & _____ points.

Each type of histogram analysis expects a particular shape & _____ of lobes for the acquired histogram.

Histogram Analysis is an averaged gray scale curve that's usually included in the displayed histogram for the image.

What type of histograms present a distinct left lobe representing the large # of pixels holding light densities?

By aligning the high/low points of the S & Q ranges, the computer can rescale the gray scale, or contrast of the image.

When the body portion of the curve is steep, it represents a _____ contrast image.

The histogram is really a bar graph, indicating the # of _____ counted for each _____ (gray level).

3 Flat field uniformity corrections

For a gray scale of 1535, 1535 individual computer files are needed.

Modern digital processing is becoming more robust & resistant to errors.

The computer can force the specific shape of the histograms to match by altering pixel count in each bin.

Steps for image analysis is segmentation, exposure field recognition, construction of histogram, histogram analysis.

An artifact will show up on the right side of a histogram.

Phosphor layers w/ slight variations in thickness cause variations in absorption efficiency.

Connecting the tops of bars (B) is a "best-fit line."

What analyzed between dark structures within the anatomy from the black background density, which must be eliminated?

The most common way to correct the dexel dropout is using a software ________.

Variable scintillator thickness is used both in DR & CR.

Rescaling, has to do with algebraically applying the same labels of _____ data regardless of what that data actually is.

At control console, selecting the ___ ____ assigns the type of histogram to be used.

Which type of histogram consists of a bell-shaped curve and is followed by a distinct "spike" in the graph.

What can have variable length, quality/flaws causing fluctuations in the light transmitted to the photomultiplier tube?

Pre-processing #1 is?

Dexel drop out steps include

What is the Qmin?

What results in a limited # of gray levels (pixel values) assigned to "bins" or computer files?

Gray of a histogram is located where?