Geometry Helpers

ImageMagick uses a handy geometry syntax to specify coordinates and shapes for use in image transformations. You can either specify these manually as strings or use the helper functions below.

Usage

geometry_point(x, y)

geometry_area(width = NULL, height = NULL, x_off = 0, y_off = 0)

geometry_size_pixels(width = NULL, height = NULL, preserve_aspect = TRUE)

geometry_size_percent(width = 100, height = NULL)

Arguments

x

left offset in pixels

y

top offset in pixels

width

in pixels

height

in pixels

x_off

offset in pixels on x axis

y_off

offset in pixels on y axis

preserve_aspect

if FALSE, resize to width and height exactly, loosing original aspect ratio. Only one of percent and preserve_aspect may be TRUE.

Details

See ImageMagick Manual for details about the syntax specification. Examples of geometry strings:

• "500x300" – Resize image keeping aspect ratio, such that width does not exceed 500 and the height does not exceed 300.

• "500x300!" – Resize image to 500 by 300, ignoring aspect ratio

• "500x" – Resize width to 500 keep aspect ratio

• "x300" – Resize height to 300 keep aspect ratio

• "50%x20%" – Resize width to 50 percent and height to 20 percent of original

• "500x300+10+20" – Crop image to 500 by 300 at position 10,20

See also

Other image: _index_, analysis, animation, attributes(), color, composite, defines, device, edges, editing, effects(), fx, morphology, ocr, options(), painting, segmentation, transform(), video

Examples

# Specify a point
logo <- image_read("logo:")
image_annotate(logo, "Some text", location = geometry_point(100, 200), size = 24)
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      640    480 sRGB       TRUE         0 72x72  

# Specify image area
image_crop(logo, geometry_area(300, 300), repage = FALSE)
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      300    300 sRGB       FALSE        0 72x72  
image_crop(logo, geometry_area(300, 300, 100, 100), repage = FALSE)
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      300    300 sRGB       FALSE        0 72x72  

# Specify image size
image_resize(logo, geometry_size_pixels(300))
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      300    225 sRGB       FALSE        0 72x72  
image_resize(logo, geometry_size_pixels(height = 300))
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      400    300 sRGB       FALSE        0 72x72  
image_resize(logo, geometry_size_pixels(300, 300, preserve_aspect = FALSE))
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      300    300 sRGB       FALSE        0 72x72  

# resize relative to current size
image_resize(logo, geometry_size_percent(50))
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      320    240 sRGB       FALSE        0 72x72  
image_resize(logo, geometry_size_percent(50, 20))
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      320     96 sRGB       FALSE        0 72x72