2.0 KiB
generate_derivatives
rake generate_derivatives, automates the creation of optimized, small and thumbnail images from all images and PDFs contained in the "objects/" directory in this repository. (Note: Optimization is not supported for Windows users.)
It outputs the derivatives to "objects/small" and "objects/thumbs".
Please ensure you have the requirements installed and available on the commandline before running!
Requirements:
- ImageMagick, download
- Ghostscript, download AGPL version
The following configuration options are available:
| option | description | default value |
|---|---|---|
| thumbs_size | the dimensions of the generated thumbnail images | 450x |
| small_size | the dimensions of the generated small images | 800x800 |
| density | the pixel density used to generate PDF thumbnails | 300 |
| missing | whether to only generate derivatives that don't already exist | true |
| compress_originals | Optimize the original image files | false |
| input_dir | Input directory | objects |
You can configure any or all of these options by specifying them in the rake command like so:
rake generate_derivatives[<thumb_size>,<small_size>,<density>,<missing>,<compress_originals>,<input_dir>]
Here's an example of overriding all of the option values:
rake generate_derivatives[100x100,300x300,70,false,false,'images']
It's also possible to specify individual options that you want to override, leaving the others at their defaults.
For example, if you only wanted to set density to 70, you can do:
rake generate_derivatives[,,70]
The mini_magick Gem is used to interface with ImageMagick so it supports both current version 7 and legacy versions (which are common on Linux). The image_optim Gem is used to optimize images using the optimization libraries provided by the image_optim_pack Gem. image_optim_pack does not provide binaries for Windows, so optimization is skipped when using the rake task on Windows.