image-coloring
change-hue
tint-image
7.4

image-coloring

thoughtstem

 (require image-coloring) package: image-coloring

This is for doing basic color shifting transformations on image? values. It does this by converting them into bitmaps and operating on the pixels. What is returned is a bitmap. So keep that in mind if you are intending to do operations like scale downstream of, say, a change-hue. If you scale up after the hue shift, you’ll see a blury image. If you scale up before, the color shift will have to operate on more pixels.

procedure

(change-hue amount img)  image?

  amount : from-0-to-360?
  img : image?
Shifts the image’s hue by the given amount.

#lang racket
(require image-coloring)
 
(change-hue 50 (circle 40 'solid 'red))

Gives us:

image

Or:

#lang racket
(require image-coloring)
 
(change-hue 50 chicken-sheet)

Gives us:

image

Whereas the original was:

image

procedure

(tint-image color img)  image?

  color : color?
  img : image?
Overlays the given color onto non-transparent pixels of img.

#lang racket
(require image-coloring)
 
(tint-image "red" chicken-sheet)

Gives us:

image

Whereas the original was:

image

TODO: Test and document the other functions in main.rkt