Easy Image Processing in R using the Magick Package

Cut and edit

Several of the transformation functions take an geometry parameter which requires a special syntax of the form AxB+C+D where each element is optional. Some examples:

• image_trim(image): Trims margin.
• image_crop(image, geometry = "100x150+50"): crop out width:100px and height:150px starting +50px from the left
• image_scale(image, geometry = "200"): resize proportionally to width: 200px
• image_scale(image, grometry = "x200"): resize proportionally to height: 200px
• image_fill(image, color = "blue", point = "+100+200"): flood fill with blue starting at the point at x:100, y:200
• image_border(frink, color = "red", geometry = "20x10"): adds a border of 20px left+right and 10px top+bottom

Change image border and background:

# Add 20px left/right and 10px top/bottom
image_border(image_background(frink, "hotpink"), "#000080", "20x10")

Trim margins:

image_trim(frink)

Crop the image. Options are here width:100px and height:150px starting +50px from the left

image_crop(frink, "100x150+50")

Resize the image:

# Width: 300px
image_scale(frink, "300") 
# Height: 300px
image_scale(frink, "x300") 

Rotate or mirror the image

image_rotate(frink, 45)
image_flip(frink)
image_flop(frink)

Modulate and paint an image:

# Change the brightness, the saturation and the Hue
image_modulate(frink, brightness = 80, saturation = 120, hue = 90)

# Paint the shirt in blue
image_fill(frink, "blue", point = "+100+200", fuzz = 20)

With image_fill we can flood fill starting at pixel point. The fuzz parameter allows for the fill to cross for adjacent pixels with similarish colors. Its value must be between 0 and 256^2 specifying the max geometric distance between colors to be considered equal. Here we give professor frink a blue shirt.

Text annotations

# Add some text
image_annotate(
  frink, text = "I like R!", size = 70, color = "green",
  gravity = "southwest"
  )

# Customize text
image_annotate(
  frink, text = "CONFIDENTIAL", size = 30, 
  color = "red", boxcolor = "pink",
  degrees = 60, location = "+50+100",
  font = "Times"
  )

Fonts that are supported on most platforms include "sans", "mono", "serif", "Times", "Helvetica", "Trebuchet", "Georgia", "Palatino"or "Comic Sans".

Stack layers on top of each other

Import and scale images:

bigdata <- image_read('https://jeroen.github.io/images/bigdata.jpg')
frink <- image_read("https://jeroen.github.io/images/frink.png")
logo <- image_read("https://jeroen.github.io/images/Rlogo.png")
img <- c(bigdata, logo, frink)
img <- image_scale(img, "300x300")
image_info(img)

##   format width height colorspace matte filesize
## 1   JPEG   300    225       sRGB FALSE        0
## 2    PNG   300    232       sRGB  TRUE        0
## 3    PNG   148    300       sRGB  TRUE        0

Print images:

# Prints images on top of one another
image_mosaic(img)

# Create a single image which has the size of the first image
image_flatten(img)

# Adding images
image_flatten(img, 'Add')

# Modulate images
image_flatten(img, 'Modulate')

# Minus
image_flatten(img, 'Minus')

Combining or appending images

Put the image frames next to each other:

image_append(image_scale(img, "x200"))

Stack images on top of each other:

image_append(image_scale(img, "100"), stack = TRUE) 

Composing allows for combining two images on a specific position:

bigdatafrink <- image_scale(image_rotate(image_background(frink, "none"), 300), "x200")
image_composite(image_scale(bigdata, "x400"), bigdatafrink, offset = "+180+100")

Create GIF animation

Animating image frames:

image_animate(image_scale(img, "200x200"), fps = 1, dispose = "previous")

Creates a sequence of n images that gradually morph one image into another.

newlogo <- image_scale(image_read("https://jeroen.github.io/images/Rlogo.png"))
oldlogo <- image_scale(image_read("https://developer.r-project.org/Logo/Rlogo-3.png"))
image_resize(c(oldlogo, newlogo), '200x150!') %>%
  image_background('white') %>%
  image_morph() %>%
  image_animate()