5.3 Histogram
This menu groups operations for finding and transforming
image histograms. nip2 represents histograms and lookup
tables as images with Type set to Histogram. Histograms may
have pixels in any format and any number of bands. You
can only find histograms of unsigned 8- and 16-bit
images.
-
New
- This makes a new ramp histogram. A set of sliders
let you adjust the shape. Use Map Histogram to apply
your ramp to an image.
Build LUT from Scatter makes a histogram from a
matrix of (x,y) values.
Tag Image as Histogram marks an image as actually
being a histogram after all.
Tone Curve builds a tone curve which you can later
apply to an image.
-
Find
- A one dimensional histogram treats each band
as an independent variable. An n-dimensional
histogram treats each pixel as a vector of n
elements, where n is the number of bands in the
image.
-
Map
- Looks up each pixel in the input in the histogram
and sends the found value to the output.
-
Equalise
- Find the global or locally histogram equalised
image.
-
Cumulative
- Use
this and friends to calculate a cumulative histogram
(integrate), normalise a histogram and match two
histograms.
-
Find Profile
- Searches from the edges of an image for the
first non-zero pixel and returns a profile histogram.
-
Find Projections
- Sum columns and rows in an image.
-
Plot Slice
- Mark a guide on an image (drag from the
image rulers, or click File / New / Guide) and click
Plot Slice to make a histogram which is a horizontal
or vertical slice through an image. Use Extract Arrow
to extract the area around an arrow or guide. Use
Plot Object to make a plot of any object.