Thumb Cutter

Thumb Cutter slices your images with blazing speed (with the help of sharp library)! It comes as express.js middleware, so you can just plug it in and start using by adding query parameters onto a standard image url. It's ideal for web developers who would like to easily experiment with different thumbnail sizes generated on the go.

You can throw at it JPEG, PNG and WebP images. Colour spaces, embedded ICC profiles and alpha transparency channels are all handled correctly.

Since Thumb Cutter is using libvips image processing library we're in for some benefits straight from Birkbeck College!

Quoting from sharp's README:

Only small regions of uncompressed image data are held in memory and processed at a time, taking full advantage of multiple CPU cores and L1/L2/L3 cache. Resizing an image is typically 4x faster than using the quickest ImageMagick and GraphicsMagick settings.

Huffman tables are optimised when generating JPEG output images without having to use separate command line tools like jpegoptim and jpegtran. PNG filtering can be disabled, which for diagrams and line art often produces the same result as pngcrush.

Everything remains non-blocking thanks to libuv, no child processes are spawned and Promises/A+ are supported.

Usage

var express = require('express'),
    app = express(),
    thumbCutter = require('thumb-cutter');

app.use('/pictures', thumbCutter.static(__dirname + '/../pictures'));

<img src="/pictures/bw/photo.jpg?dim=200x100&amp;rotate=true" alt="" />

Install

npm install thumb-cutter

libvips is required for this module, so make sure it is installed.

Debian

apt-get install libvips libvips-dev libgsf-1-dev

Mac OS X

brew install vips

Documentation

thumbCutter.static(path, [options])

Middleware to replace express.static() or connect.static().

path is the base directory where images are located.

options is an object to specify customizations. It currently has the following options:

• cacheDir The directory where generated images will be created. (default: [path]/.cache/)
• quality The output quality to use for lossy JPEG, WebP and TIFF output formats. (default: 80)
• rotate Rotate the output image by either an explicit angle or auto-orient based on the EXIF Orientation tag. (default: false)
• progressive Use progressive (interlace) scan for JPEG and PNG output. (default: true)
• withMetadata Include all metadata (EXIF, XMP, IPTC) from the input image in the output image. This will also convert to and add the latest web-friendly v2 sRGB ICC profile. (default: false)
• setHeaders Callback with signature function(res, filepath), called before res.sendFile(filepath)

Resizing of images is directed by the query parameter dim. This is in the format [width]x[height]. E.g. red.gif?dim=200x100

Resized images will be created on an as needed basis, and stored in cacheDir.

If there is no parameters present, the original image will be served.

thumbCutter.convert(options, callback)

The first argument is an options object. callback argument is required.

• src (required) Path to source image
• dst (required) Path to destination image
• width Width of resized image
• height Height of resized image
• quality The output quality to use for lossy JPEG, WebP and TIFF output formats.
• rotate Rotate the output image by either an explicit angle or auto-orient based on the EXIF Orientation tag.
• progressive Use progressive (interlace) scan for JPEG and PNG output.
• withMetadata Include all metadata (EXIF, XMP, IPTC) from the input image in the output image. This will also convert to and add the latest web-friendly v2 sRGB ICC profile.

The callback argument gets 2 arguments. The first is an error object, most likely from sharp. The second argument is the path to the created image.