Optimize and Compress Image Files with 'reSmush.it'.

resmush

resmush is a R package that allows users to optimize and compress images using reSmush.it. reSmush.it is a free AP/u that provides image optimization and has been implemented in WordPress and many other tools.

Some of the features of reSmush.it include:

• Free optimization services with no API key required.
• Support for both local and online images.
• Supported image formats: png, jpg/jpeg, gif, bmp, tiff.
• Maximum image size: 5 MB.
• Compression using several algorithms:
  • PNGQuant: Removes unnecessary chunks from png files while preserving a full alpha transparency.
  • JPEGOptim: Lossless optimization based on Huffman table optimization.
  • OptiPNG: A png optimizer used by several online compression tools.

Installation

install.packages("resmush")

# install.packages("pak")
pak::pak("dieghernan/resmush")

# Install resmush in R:
install.packages(
  "resmush",
  repos = c(
    "https://dieghernan.r-universe.dev",
    "https://cloud.r-project.org"
  )
)

Example

Compressing an online jpg image:

library(resmush)

url <- "https://dieghernan.github.io/resmush/img/jpg_example_original.jpg"

resmush_url(
  url,
  outfile = "man/figures/jpg_example_compress.jpg",
  overwrite = TRUE
)
#> ══ resmush summary ═════════════════════════════════════════════════════════════
#> ℹ Input: 1 url with size 178.7 Kb
#> ✔ Success for 1 url: Size now is 45 Kb (was 178.7 Kb). Saved 133.7 Kb (74.82%).
#> See result in directory 'man/figures'.

The compression quality for jpg files can be adjusted using the qlty argument. However, it is recommended to keep this value above 90 to maintain good image quality.

# Extreme case
resmush_url(
  url,
  outfile = "man/figures/jpg_example_compress_low.jpg",
  overwrite = TRUE,
  qlty = 3
)
#> ══ resmush summary ═════════════════════════════════════════════════════════════
#> ℹ Input: 1 url with size 178.7 Kb
#> ✔ Success for 1 url: Size now is 2.2 Kb (was 178.7 Kb). Saved 176.4 Kb (98.74%).
#> See result in directory 'man/figures'.

All the functions return (invisibly) a dataset summarizing the process. The following example shows how this works when compressing a local file:

png_file <- system.file("extimg/example.png", package = "resmush")

# For the example, copy to a temporary file
tmp_png <- tempfile(fileext = ".png")
file.copy(png_file, tmp_png, overwrite = TRUE)
#> [1] TRUE

summary <- resmush_file(tmp_png, overwrite = TRUE)

tibble::as_tibble(summary[, -c(1, 2)])
#> # A tibble: 1 × 6
#>   src_size dest_size compress_ratio notes src_bytes dest_bytes
#>   <chr>    <chr>     <chr>          <chr>     <dbl>      <dbl>
#> 1 239.9 Kb 70.7 Kb   70.54%         OK       245618      72356

Other alternatives

Several other R packages also provide image optimization tools:

• xfun (Xie 2024), which includes:
  • xfun::tinify(): Similar to resmush_file() but uses TinyPNG and requires an API key.
  • xfun::optipng(): Compresses local files using OptiPNG, which must be installed locally.
• tinieR by jmablog: An R interface to TinyPNG.
• optout by @coolbutuseless: Similar to xfun::optipng() but with more options. Requires additional local software.

Table 1: R packages: Comparison of alternatives for optimizing images.

Table 2: R packages: Supported formats.

Citation

Hernangómez D (2026). resmush: Optimize and Compress Image Files with reSmush.it. doi:10.32614/CRAN.package.resmush, https://dieghernan.github.io/resmush/.

A BibTeX entry for LaTeX users is

@Manual{R-resmush,
  title = {{resmush}: Optimize and Compress Image Files with {reSmush.it}},
  doi = {10.32614/CRAN.package.resmush},
  author = {Diego Hernangómez},
  year = {2026},
  version = {1.0.0},
  url = {https://dieghernan.github.io/resmush/},
  abstract = {Compress local and online images using the reSmush.it API service <https://resmush.it/>.},
}

References