TB4 Flashcards
What determines pixel resolution?
Number of pixels
Define: voxel
a unit of graphic information that defines a point in 3D space
(hint: pixel is defines a point in 2D space)
Define: metadata
provides information about other data, but not the content of the data
What does a higher bit allow for?
Smoother transition between ‘levels’
Define: dead pixel
when all three RGB sub-pixels are turned off, creating a black spot on the display
Define: segmentation threshold
You need to identify the boundaries of the object by applying the segmentation threshold, whereby you define an intensity limit. Anything with an intensity lower than the limit is classed as background.
What do intensity histograms show? What can they be used for?
It shows the number of pixels in an image at each different intensity value found in that image.
They can be used to decide threshold values.
Define: image dilation
enlarge ‘blobs’
Define: image erosion
shrink ‘blobs’
Define: watershed
Splits blobs when there is a slight peak of intensities, suggesting they’re individual objects
Define: colocalization
In fluorescence microscopy, colocalization refers to observation of the spatial overlap between two or more different fluorescent labels, each having a separate emission wavelength. It’s shown via the mix of red and green (shown as yellow) and used to determine if biochemical reactions are occurring between molecules.
Define: Pearson’s correlation test
A measure of the strength of a linear association between two variables, denoted by r. It can be used on any two images as long as they are the same spatial size and don’t have too many black pixels to show if colocalization has occurred or not.
What is the Pearson test insensitive to?
linear changes in intensity
What is the Pearson test sensitive to?
spectral bleed through (increases the coefficient); noise (decreases the coefficient)
