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Clojure image processing library

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README.md

RinzeLight

RinzeLight is an image processing library inspired and based on RMagick4J.

Usage

1.- Read an image. It can be read from a lot of sources.

(def img (read-image "path-to-an-image"))

2.- Display it.

(display-image img)

3.- Save it.

(write-image img "another-path")

Modifying an image

Currently, there are only three methods to modify an image: map-image, map-pixel-location and apply-lookup-table.

map-image

map-image accepts two parameters: a function and an image. The function receives a pixel structure and must return a pixel.

For example, for inverting an image img you can use the following code:

(use 'rinzelight.effects.basic-effects)
(use 'rinzelight.pixel)

(map-image invert-pixel img)

map-pixel-location

map-pixel-location receives either two or four parameters. If final image has the same width and height as the original, only img and function is needed. Otherwise, new width and height are needed. The function receives a two-length vector representing current pixel location and must return a two-length vector representing new location for current pixel.

You can use functions in rinzelight.effects.helper-functions for some basic effects, like rotating left and right. See examples dir for more of these functions.

(def img (read-image "samples/northern-lights.clj"))

(def new-size (vertical-flip-new-size img))

(map-pixel-location (vertical-flip img) img
                    (new-size 0)
                    (new-size 1))

apply-lookup-table

apply-lookup-table accepts two parameters: an image and a lookup table. Then, it applies the lookup table to the image and return a new one.

There are a few one-dimensional lookup tables:

  • zero: Returns zero for any value.
  • straight: Returns the same value it receives.
  • invert: Returns quantum-range - x, being x the received value.
  • brighten: It is used to brighten the image.
  • better-brighten: It produces a better brightened image.
  • posterize: Used for posterizing an image.

For creating a multidimensional lookup-table, see:

(doc multisample-lookup-table)

It is really easy.

You can create a lookup table from a pixel function, but take into account that result may differ from what you expected.

For applying a lookup-table, just use apply-lookup-table like this:

(def img (read-image "samples-northern-lights")    

(def only-green (multisample-lookup-table zero
                                          zero
                                          straight))

(apply-lookup-table img only-green)

If a pixel function can be expressed as a lookup table, use this method since it is way faster than map-image.

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