Using resmush • resmush

resmush is a R package that allows users to optimize and compress images using reSmush.it. reSmush.it is a free API 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.

Example

Compressing an online jpg image:

library(resmush)

url <- paste0(
  "https://raw.githubusercontent.com/dieghernan/",
  "resmush/main/img/jpg_example_original.jpg"
)

resmush_url(url, outfile = "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 '.'.

Original picture (top): 178.7 Kb; Optimized picture (bottom): 45 Kb (Compression: 74.8%). Click to enlarge.

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 = tempfile(fileext = ".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 'tempdir()'.

Low quality image due to a high compression rate.

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.
tool	CRAN	Additional software?	Online?	API Key?	Limits?
`xfun::tinify()`	Yes	No	Yes	Yes	500 files/month (free tier)
`xfun::optipng()`	Yes	Yes	No	No	No
tinieR	No	No	Yes	Yes	500 files/month (free tier)
optout	No	Yes	No	No	No
resmush	Yes	No	Yes	No	Max size 5 MB

Table 2: R packages: Supported formats.
tool	png	jpg	gif	bmp	tiff	webp	pdf
`xfun::tinify()`	✅	✅	❌	❌	❌	✅	❌
`xfun::optipng()`	✅	❌	❌	❌	❌	❌	❌
tinieR	✅	✅	❌	❌	❌	✅	❌
optout	✅	✅	❌	❌	❌	❌	✅
resmush	✅	✅	✅	✅	✅	❌	❌

References

Xie, Yihui. 2024. xfun: Supporting Functions for Packages Maintained by Yihui Xie. https://github.com/yihui/xfun.