geometry function

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.

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

Examples

# Specify a point
logo <- image_read("logo:")
image_annotate(logo, "Some text", location = geometry_point(100, 200), size = 24)

# Specify image area
image_crop(logo, geometry_area(300, 300), repage = FALSE)
image_crop(logo, geometry_area(300, 300, 100, 100), repage = FALSE)

# Specify image size
image_resize(logo, geometry_size_pixels(300))
image_resize(logo, geometry_size_pixels(height = 300))
image_resize(logo, geometry_size_pixels(300, 300, preserve_aspect = FALSE))

# resize relative to current size
image_resize(logo, geometry_size_percent(50))
image_resize(logo, geometry_size_percent(50, 20))

See Also

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