Tools for Working with Image Pixels

Description

This package provides tools to show and draw image pixels using 'HTML' widgets and 'Shiny' applications.

Details

This package can be used to: Visualize the 'MNIST' dataset for handwritten digit recognition, create simple test cases for image classification, or to create new datasets by building a 'Shiny' applicaiton that enables many users to capture images for supervised learning.

Author(s)

Maintainer: Javier Luraschi javier@rstudio.com

Other contributors:

• RStudio [copyright holder]

See Also

Useful links:

• https://github.com/javierluraschi/pixels

• Report bugs at https://github.com/javierluraschi/pixels/issues

Gets Pixels

Description

Creates an ShinyGadget to retrieve pixels.

Usage

get_pixels(pixels = NULL, grid = c(28, 28), size = c(250, 250),
  brush = matrix(c(0, 0.5, 0.8, 0.5, 0, 0.5, 1, 1, 1, 0.5, 0.8, 1, 1, 1, 0.8,
  0.5, 1, 1, 1, 0.5, 0, 0.5, 0.8, 0.5, 0), 5, 5), params = list(fill =
  list(color = "#555555"), grid = list(color = "#EEEEEE")))

Arguments

Shiny Widget Output

Description

Provides a Shiny Widget for Output.

Usage

shiny_pixels_output(outputId, width = "100%", height = "400px")

Arguments

Examples

library(shiny)

ui <- fluidPage(
  tags$head(
    tags$style(HTML("
      #pixels {
        height: 270px !important;
        margin-top: 10px;
      }
    "))
  ),
  titlePanel("Digit Capture Application"),
  textOutput("prompt"),
  shiny_pixels_output("pixels"),
  actionButton("captureDigit", "Capture")
)

server <- function(input, output) {
  output$pixels <- shiny_render_pixels(
    show_pixels()
  )

  digit <- reactiveVal(floor(runif(1, 1, 10)))
  output$prompt <- renderText(paste0("Please draw number ", digit(), ":"))

  observeEvent(input$captureDigit, {
    digit_path <- file.path("digits", digit())
    if (!dir.exists(digit_path)) dir.create(digit_path, recursive = TRUE)
    saveRDS(input$pixels, paste0(digit_path, "/", as.numeric(Sys.time()), ".rds"))
 
    digit(floor(runif(1, 1, 10)))
    output$pixels <- shiny_render_pixels(
      show_pixels()
    )
  })
}

if (interactive()) {
  shinyApp(ui = ui, server = server)
}

Shiny Widget Render

Description

Renders the Shiny Widget.

Usage

shiny_render_pixels(expr, env = parent.frame(), quoted = FALSE)

Arguments

See Also

[shiny_pixels_output()] for an example of using this function within a 'Shiny' application.

Show Pixels

Description

Creates an HTMLWidget to show pixels.

Usage

show_pixels(pixels = NULL, grid = c(28, 28), size = c(250, 250),
  brush = matrix(c(0, 0.5, 0.8, 0.5, 0, 0.5, 1, 1, 1, 0.5, 0.8, 1, 1, 1, 0.8,
  0.5, 1, 1, 1, 0.5, 0, 0.5, 0.8, 0.5, 0), 5, 5), params = list(fill =
  list(color = "#555555"), grid = list(color = "#EEEEEE")))

Arguments

Examples

library(pixels)
show_pixels(
  round(runif(400, 0, 1)),
  grid = c(40, 10),
  size = c(800, 200),
  params = list(fill = list(color = "#FF3388"))
)