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.