Package 'countcolors'

Change all specified pixels to a new color

Description

Changes pixels in an image to a different color and displays and/or returns the re-colored image.

Usage

changePixelColor(pixel.array, pixel.idx, target.color = "green",
  return.img = FALSE, plotting = TRUE, main = "")

Arguments

pixel.array	An image represented as a 3D array (as read in by readJPEG, readPNG, or loadImage) in which to change pixel colors.
pixel.idx	An n x 2 matrix of index coordinates specifying which pixels to change, where rows are pixels and columns are X and Y coordinates in the image.
target.color	Color with which to replace specified pixels. Can be either a an RGB triplet or one of the colors listed by colors.
return.img	Logical. Should RGB array with swapped colors be returned?
plotting	Logical. Should output be plotted in the plot window?
main	Optional title to display for image.

Value

Raster array with indicated pixels changed to target color, if return.img = TRUE.

Examples

# Change a rectangle in the center to black
flowers <- jpeg::readJPEG(system.file("extdata", "flowers.jpg", package =
"countcolors"))

sinister.object <- expand.grid(c(114:314), c(170:470))

countcolors::changePixelColor(flowers, sinister.object, target.color = "black")

## Not run: 
# Change all the white flowers to magenta
indicator.img <- countcolors::sphericalRange(flowers, center = c(1, 1, 1),
radius = 0.1, color.pixels = TRUE, plotting = FALSE)

countcolors::changePixelColor(flowers, indicator.img$pixel.idx,
target.color="magenta")

## End(Not run)

---

Count the number of pixels within a color range or ranges

Description

Counts the pixels within a color range; ranges can be spherical (see sphericalRange) or rectangular (rectangularRange). If multiple ranges are specified, each one is colored using a different indicator color. Uses standard RGB (sRGB) color profile for display.

Usage

countColors(path, color.range = "spherical", center, radius, lower,
  upper, bg.lower = rep(0.8, 3), bg.upper = rep(1, 3),
  target.color = c("magenta", "cyan", "yellow"), plotting = FALSE,
  save.indicator = FALSE, dpi = 72, return.indicator = FALSE)

Arguments

path	Path to the image (JPEG or PNG).
color.range	Type of range being specified. Must be either "spherical" or "rectangular".
center	A vector or n x 3 matrix of color centers (RGB triplets) around which to search using spherical color range. RGB range 0-1 (not 0-255). See details.
radius	Values between 0 and 1 specifying the size of the area around center to search. The same number of centers and radii must be specified.
lower, upper	RGB triplet(s) specifying the bounds of color space to search. RGB range 0-1 (not 0-255). Must be the same length. See details.
bg.lower, bg.upper	RGB triplets specifying the bounds of color space to ignore as background, or NULL to use the entire image. RGB range 0-1 (not 0-255).
target.color	If an indicator image is created, the color with which to replace specified pixels. Can be either an RGB triplet or one of the colors listed by colors.
plotting	Logical. Should output be plotted in the plot window?
save.indicator	Logical. If TRUE, saves image to the same directory as the original image as 'originalimagename_masked.png'; if a path is provided, saves it to that directory/name instead, also as a PNG.
dpi	Resolution (dots per image) for saving indicator image.
return.indicator	Logical. Should an indicator image (RGB array with targeted pixels changed to indicator color) be returned?

Details

More than one set of ranges can be specified for the color search space, but the same number of arguments must be provided in each case (so the number of pixels and centers must be the same if using a spherical range, and the number of upper and lower bounds must be the same if using a rectangular one).

For center, upper, and lower, which call for RGB triplets, provide either a vector of RGB triplets in RGB order, i.e. c(R1, G1, B1, R2, G2, B2, etc) or a 3-column matrix with one row per RGB triplet. If a vector is provided, it is coerced to a 3-column matrix, and must therefore be a multiple of 3. All RGB values are interpreted to be in sRGB color space (not Adobe).

Value

A list with the following attributes:

• pixel.idx: Unique coordinates of pixels within color range(s).

• pixel.fraction: Proportion of the non-background image within color range(s), found by dividing the number of pixels in pixel.idx by the number of non-background pixels in the image.

• indicator.img: If return.indicator = TRUE, RGB array with color-swapped pixels.

See Also

countColorsInDirectory

Examples

# Try out a few different radii for white pelicans
pelicans <- system.file("extdata", "pelicans.jpg", package = "countcolors")

white.ctr <- rep(0.9, 9)
white.radii <- c(0.5, 0.3, 0.1)

# Magenta = 50% threshold, cyan = 30% threshold, yellow = 10% threshold
pelican.example <- countcolors::countColors(pelicans, center = white.ctr,
radius = white.radii, bg.lower = NULL, plotting = TRUE)

---

Count colors within range(s) in every image in a directory

Description

A wrapper for countColors that finds every image (JPEG or PNG) in a #' folder and counts colors in each image.

Usage

countColorsInDirectory(folder, color.range = "spherical", center, radius,
  lower, upper, bg.lower = rep(0.8, 3), bg.upper = rep(1, 3),
  target.color = c("magenta", "cyan", "yellow"), plotting = FALSE,
  save.indicator = FALSE, dpi = 72, return.indicator = FALSE)

Arguments

folder	Path to a folder containing images.
color.range	Type of range being specified. Must be either "spherical" or "rectangular".
center	A vector or n x 3 matrix of color centers (RGB triplets) around which to search using spherical color range. RGB range 0-1 (not 0-255). See details.
radius	Values between 0 and 1 specifying the size of the area around center to search. The same number of centers and radii must be specified.
lower	RGB triplet(s) specifying the bounds of color space to search. RGB range 0-1 (not 0-255). Must be the same length. See details.
upper	RGB triplet(s) specifying the bounds of color space to search. RGB range 0-1 (not 0-255). Must be the same length. See details.
bg.lower	RGB triplets specifying the bounds of color space to ignore as background, or NULL to use the entire image. RGB range 0-1 (not 0-255).
bg.upper	RGB triplets specifying the bounds of color space to ignore as background, or NULL to use the entire image. RGB range 0-1 (not 0-255).
target.color	If an indicator image is created, the color with which to replace specified pixels. Can be either an RGB triplet or one of the colors listed by colors.
plotting	Logical. Should output be plotted in the plot window?
save.indicator	Logical. If TRUE, saves image to the same directory as the original image as 'originalimagename_masked.png'; if a path is provided, saves it to that directory/name instead, also as a PNG.
dpi	Resolution (dots per image) for saving indicator image.
return.indicator	Logical. Should an indicator image (RGB array with targeted pixels changed to indicator color) be returned?

Value

A list of countColors lists, one for each image.

See Also

countColors

Examples

## Not run: 
folder <- system.file("extdata", package = "countcolors")

# Screen out white in both the flower image and the pelican image
upper <- c(1, 1, 1)
lower <- c(0.8, 0.8, 0.8)

white.screen <- countcolors::countColorsInDirectory(folder, color.range =
"rectangular", upper = upper, lower = lower, bg.lower = NULL, plotting =
TRUE, target.color = "turquoise")

## End(Not run)

---

Plot a 3D array as an RGB image

Description

Plots a 3D array as an sRGB image in the plot window.

Usage

plotArrayAsImage(rgb.array, main = "")

Arguments

rgb.array	3D RGB array with R, G, and B channels (pixel rows x pixel columns x color channels) to be plotted in the plot window as an actual image.
main	Optional title to display for image.

Examples

# Read in image
flowers <- jpeg::readJPEG(system.file("extdata", "flowers.jpg", package =
"countcolors"))

# Plot
plotArrayAsImage(flowers, main = "flowers!")

---

Find pixels within a target color range defined by boundaries in each channel

Description

Searches for pixels within a set of upper and lower limits for each color channel. Essentially draws a 'box' around a region of color space in which to search for pixels.

Usage

rectangularRange(pixel.array, upper, lower, target.color = "green",
  main = "", color.pixels = TRUE, plotting = TRUE)

Arguments

pixel.array	An image represented as a 3D array (as read in by readJPEG, readPNG, or loadImage) in which to change pixel colors.
upper, lower	RGB triplet specifying the bounds of color space search. See details.
target.color	Color with which to replace specified pixels. Can be either an RGB triplet or one of the colors listed by colors.
main	Optional title to display for image.
color.pixels	Logical. Should a diagnostic image with pixels changed to target.color be returned?
plotting	Logical. Should output be plotted in the plot window?

Details

lower and upper should be vectors of length 3 in a 0-1 range, in the order R-G-B. For example, the upper bounds for white would be c(1, 1, 1), and the lower bounds might be c(0.8, 0.8, 0.8). This would search for all pixels where the red value, blue value, AND green value are all between 0.8 and 1. All RGB values are interpreted to be in sRGB color space (not Adobe).

Value

A list with the following elements:

• pixel.idx: Coordinates of pixels within color range.

• img.fraction: Proportion of the image within color range.

• original.img: The original RGB array.

• indicator.img: If color.pixels = TRUE, RGB array with color-swapped pixels.

Examples

flowers <- jpeg::readJPEG(system.file("extdata", "flowers.jpg", package =
"countcolors"))

# Define upper and lower bounds for white
lower <- rep(0.8, 3)
upper <- rep(1, 3)

white.flowers <- countcolors::rectangularRange(flowers, rep(1, 3), rep(0.85,
3), target.color = "turquoise")

---

Find pixels within a target color range defined by a center and search radius

Description

Searches for pixels within a radius of a single color. Draws a sphere around a region of color space in which to search for pixels.

Usage

sphericalRange(pixel.array, center, radius, target.color = "green",
  main = "", color.pixels = TRUE, plotting = TRUE)

Arguments

pixel.array	An image represented as a 3D array (as read in by readJPEG, readPNG, or loadImage) in which to change pixel colors.
center	A single color (RGB triplet) around which to search. RGB range 0-1 (not 0-255).
radius	A value between 0 and 1 specifying the size of the area around center to search.
target.color	Color with which to replace specified pixels. Can be either a an RGB triplet or one of the colors listed by colors.
main	Optional title to display for image.
color.pixels	Logical. Should a diagnostic image with pixels changed to target.color be returned?
plotting	Logical. Should output be plotted in the plot window?

Details

lower and upper should be vectors of length 3 in a 0-1 range, in the order R-G-B. For example, the upper bounds for white would be c(1, 1, 1), and the lower bounds might be c(0.8, 0.8, 0.8). This would search for all pixels where the red value, blue value, AND green value are all between 0.8 and 1. All RGB values are interpreted to be in sRGB color space (not Adobe).

Value

A list with the following elements:

• pixel.idx: Coordinates of pixels within color range.

• img.fraction: Proportion of the image within color range.

• original.img: The original RGB array.

• indicator.img: If color.pixels = TRUE, RGB array with color-swapped pixels.

Examples

# Target color: change all of the red flowers to turquoise
flowers <- jpeg::readJPEG(system.file("extdata", "flowers.jpg", package =
"countcolors"))

# Red:
center <- c(255, 75, 75) / 255

# Setting the radius too low:
red.flowers <- countcolors::sphericalRange(flowers, center = center, radius =
0.05, target.color = "turquoise")

# Setting the radius too high:
red.flowers <- countcolors::sphericalRange(flowers, center = center, radius =
0.4, target.color = "turquoise")

# Setting the radius just right:
red.flowers <- countcolors::sphericalRange(flowers, center = center, radius =
0.2, target.color = "turquoise")

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