See figure 2.11.
VIPS represents histograms and look-up tables in the same way -- as images.
They should have either Xsize
or Ysize
set to 1, and the
other dimension set to the number of elements in the table. The table can be
of any size, have any band format, and have any number of bands.
Use im_histgr()
to find the histogram of an image. Use
im_histnD()
to find the n-dimensional histogram of an n-band
image. Perform operations on histograms with im_histcum()
,
im_histnorm()
, im_histspec()
, im_invertlut()
. Visualise
histograms with im_histplot()
. Use a histogram (or LUT) to transform
an image with im_maplut()
. Build a histogram from scratch with
im_identity()
or im_identity_ushort()
.
Use im_lhist*()
for local histogram equalisation, and
im_stdif*()
for statisticaol differencing. The im_tone_*()
functions are for operations on the L channel of a LAB image. Other
functions are useful combinations of these basic operations.