Image pre-processing I & II Flashcards
Image processing is also called
Image restoration
Image pre-processing is ….
a preparatory phase to improve image quality as a basis for further analysis
Unprocessed images can be very
noisy, incomplete and inconsistent
Errors in image classification can be divided into two. What are they?
System and non-system errors
Internal errors due to the sensor itself is
System errors
External errors are ?
non-system errors
A system error caused by failure of one of the detectors is
line drop-outs
A system error caused by incorrect calibration of one of the n detectors is
N-line striping
An error caused by variations of neighboring forward and backward scans of the landsat thematic mapper is ….
Banding
Failure of one or more detectors to start collecting data along a line is
line-start
An error that is created due to atmospheric haze which scatters short wavelengths bands is called
Uniformly elevated values
An error due to unpredictable or unsystematic performance of the sensor is
random noise
When does striping occur?
when a detector goes out of adjustment
Banding is most evident in ?
water bodies or areas with low variability
Line drop out can be removed by …
Principal component analysis (PCA)
A common device error caused by either a failed detector or a completely saturated is called
Line drop out
If an image is already geo referenced, will destriping work?
No
What are the two sources of u systematic errors?
Topography and atmosphere attenuation
Error when the ground swath is skewed is called
Scan skew
Error due to change in speed of the platform is called
platform velocity
Error due to rotation of the earth during scan period is
earth’s rotation
Error when the rate of scanning is not constant is
mirror scan velocity
Error when sensors produce images whose pixels are not square is
aspect ratio
Pixel values in commercially available satellite 📡 imagery represent radiance in the form of ….
Digital numbers (DN)
Assigning coordinates to known locations is
rectification
Resetting the pixels to match the ground control point is
Resampling
The process of making an image conform to another image is
Registration
A specific pixel on an image or location on a map whose geographic coordinates are known is called
ground control point
……are needed for geo referencing.
GCP’s
…… are used to correct image distortions by matching image coordinates to the map.
GCP’s
The process of transforming the data from one grid system into another an nth order polynomial is called
rectification
The two types of transformation available for rectification are
linear and non-linear transformation
Raw remote sensing data contain distortions, preventing overlay with map layers, comparison between image scenes, and with new geographic coordinates. Which geometric correction can be used?
Rectification
Since pixels of new grid systems do not align with old grid systems, the former must be ?
resampled
Resampling is also known as
pixel value or intensity interpolation
Example of radiometric correction is ?
Mosaicking, FLAASH, Quac
Geo referencing is an example of what type of pre processing?
Geometric correction
……. helps convert data to real world coordinates
geometric correction
The resampling method that assigns output pixel values by interpolating brightness values into two orthogonal directions in the input image is called
Bilinear interpolation
What resampling method is the slowest ?
Cubic convolution
The most computationally intensive resampling method is ?
cubic convolution
Which geometric correction method is known to cause the problem of duplicating pixel values and loss of some pixel values ?
nearest neighbor
…… is done to remove effects of atmosphere from the data.
atmosphere correction or modeling
What is used to create output images by combining the DN’s of different bands mathematically?
Indices
……. is used as a method of data compression.
principal component analysis
……uses a more complicated mathematical combination of many bands to define vegetation.
Tasseled Cap Transformation (T-Cap)
