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Histogram

Other Guile-CV histogram procedures and methods.

Procedures

im-histogram

Procedure: im-histogram image [#:subtitle “Untitled”] ¶

Returns two values: (1) an image; (2) a list (or a list of list) of significant values for image: one list if image is GRAY, a list of list of values per channel if image is RGB.

The returned image is composed of a header (title, #:subtitle), either the GRAY or the RGB channel histogram(s) for image and a footer, which is a table containg, for each channel, the following values: mean, standard deviation, minimum, maximum, the mode¹¹ followed by its value.

Here below, the call sequence and the histogram for the GRAY image sinter.png given along with Guile-CV documentation and examples:

scheme@(guile-user)> (im-load "sinter.png")
$32 = (212 128 1 (#f32(25.0 39.0 50.0 52.0 51.0 45.0 # …)))
scheme@(guile-user)> (im-histogram $32 #:subtitle "sinter.png")
$34 = (282 271 1 (#f32(255.0 255.0 255.0 255.0 255.0 # …)))
$35 = (27136 163.346 75.081 0 243 215 727)

Note that histogram images returned by im-histogram have no borders, the above histogram has been padded - using (im-padd $34 1 1 1 1 #:color '(96 96 96)) - for better readability, otherwise the title above and the table below would look as if they were not centered.