Histograms and look-up tables are 1xn or nx1 images, where n is less than 256 or less than 65536, corresponding to 8- and 16-bit unsigned int images. They are tagged with a VipsInterpretation of VIPS_INTERPRETATION_HISTOGRAM and usually displayed by user-interfaces such as nip2 as plots rather than images.

These functions can be broadly grouped as things to find or build histograms (vips_hist_find(), vips_hist_find_indexed(), vips_hist_find_ndim(), vips_buildlut(), vips_identity()), operations that manipulate histograms in some way (vips_hist_cum(), vips_hist_norm()), operations to apply histograms (vips_maplut()), and a variety of utility operations.

A final group of operations build tone curves. These are useful in pre-press work for adjusting the appearance of images. They are designed for CIELAB images, but might be useful elsewhere.

Functions

• vips_maplut()
• vips_percent()
• vips_stdif()
• vips_hist_cum()
• vips_hist_norm()
• vips_hist_equal()
• vips_hist_plot()
• vips_hist_match()
• vips_hist_local()
• vips_hist_ismonotonic()
• vips_hist_entropy()
• vips_case()