test_image: Test images in various R formats

In fastpng: Read and Write PNG Files with Configurable Decoder/Encoder Options

Test images in various R formats

Description

A nested named list of test images (300 x 200 pixels).

Usage

test_image

Format

An object of class list of length 9.

Details

Possible image color spaces within each image type

$gray

Gray pixels representing intensity only

$gray_alpha

Gray pixels with an alpha channel

$rgb

RGB color image

$rgba

RGB color image with alpha channel

A description of the image data within each image type

test_image$array

Arrays of numeric values in the range [0, 1]

$gray

A 2D matrix

$gray_alpha

A 3D array with 2 planes i.e. dim(x)[3] == 2

$rgb

A 3D array with 3 planes i.e. dim(x)[3] == 2

$rgba

A 3D array with 4 planes i.e. dim(x)[3] == 2

test_image$array_16bit

Same as test_image$array data except values contain 16 bits of signficant color information.

test_image$array_int

Arrays of integer values in the range [0, 255]

$gray

A 2D matrix

$gray_alpha

A 3D array with 2 planes i.e. dim(x)[3] == 2

$rgb

A 3D array with 3 planes i.e. dim(x)[3] == 2

$rgba

A 3D array with 4 planes i.e. dim(x)[3] == 2

test_image$array_int_16bit

Same as test_image$array_int data except values are in the range [0, 65535]

test_image$raster

$rgb

Raster image of color values given as hex codes #RRGGBB

$rgba

Raster image of color values given as hex codes #RRGGBBAA

$named

Raster image of color values given as R color names e.g. 'red', 'blue'

test_image$nativeraster

Integer matrix of integer values. Each 32-bit numeric value holds a packed RGBA pixel

$rgba

test_image$indexed

$integer_index

An integer matrix. Each value is an index into a separately specified color-lookup table

$numeric_index

A numeric matrix. Each value is an index into a separately specified color-lookup table

$palette

An example color palette to use with indexed images. 256 colors.

test_image$raw

Sequences of raw bytes with attributes specifying 'width', 'height', 'depth' (i.e. number of colors) and 'bits' (number of bits for each color)

$gray

Sequence of gray pixels i.e. GGGG

$gray_alpha

Sequence of GA pixels i.e. GAGAGA...

$rgb

Sequence of RGB pixels i.e. RGBRGBRGB...

$rgba

Sequence of RGB pixels i.e. RGBARGBARGBA...

test_image$raw_16_bit

The same as test_image$raw except each color takes 2 raw bytes.

fastpng documentation built on April 3, 2025, 10:01 p.m.