goptimize/README.md

# Goptimizer - downscales and optimizes images

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Goptimizer is a commandline utility written in Golang. It downscales and optimizes JPEG, PNG, GIF, TIFF and BMP files.

Image downscaling/rotation is done within goptimize (`-m <width>x<height>`, see [Usage](#usage-options)), however optimization is done using the following additional tools (if they are installed):

- jpegtran (`libjpeg-turbo-progs`) or jpegoptim
- optipng
- pngquant
- gifsicle


## Notes

Both `jpegoptim` & `jpegtran` have almost identical optimization, so if both are installed then just `jpegtran` is used for JPG optimization. PNG optimization however will run through both `optipng` & `pngquant` (if installed) as this can result in better optimization.

It is highly recommended to install the necessary optimization tools, however they are not required to run goptimize.

Goptimize will remove all exif data from JPEG files, auto-rotating those that depend on it for orientation.

It will also preserve (by default) the file's original modification times (`-p=false` to disable).

Animated GIF files are not supported and automatically get skipped.


## Usage options

```
Usage: ./goptimize [options] <images>

Options:
  -q, --quality int        quality, JPEG only (default 75)
  -m, --max string         downscale to a maximum width & height in pixels (<width>x<height>)
  -o, --out string         output directory (default overwrites original)
  -p, --preserve           preserve file modification times (default true)
  -u, --update             update to latest release
  -v, --version            show version number
  -h, --help               show help
      --jpegtran string    jpegtran binary (default "jpegtran")
      --jpegoptim string   jpegoptim binary (default "jpegoptim")
      --gifsicle string    gifsicle binary (default "gifsicle")
      --pngquant string    pngquant binary (default "pngquant")
      --optipng string     optipng binary (default "optipng")
```


## Examples

- `./goptimize image.png` - optimize a PNG file
- `./goptimize -m 800x800 *` - optimize and downscale all image files to a maximum size of 800x800px
- `./goptimize -m 1200x0 image.jpg` - optimize and downscale a JPG file to a maximum size of width of 1200px
- `./goptimize -o out/ image.jpg` - optimize a JPG file and save it to `out/`


## Install

Download the appropriate binary from the [releases](https://github.com/axllent/goptimize/releases/latest), or if you have golang installed 


### Build requirements

Go >= 1.11 required.

```
go get github.com/axllent/goptimize
```

## TODO

Some ideas for the future:

- Dry run
- Option to copy exif data (how?)