sharp/docs/api-utility.md

format

An Object containing nested boolean values representing the available input and output formats/methods.

Examples

console.log(sharp.format);

Returns Object

interpolators

An Object containing the available interpolators and their proper values

Type: string

nearest

Nearest neighbour interpolation. Suitable for image enlargement only.

bilinear

Bilinear interpolation. Faster than bicubic but with less smooth results.

bicubic

Bicubic interpolation (the default).

locallyBoundedBicubic

LBB interpolation. Prevents some "acutance" but typically reduces performance by a factor of 2.

nohalo

Nohalo interpolation. Prevents acutance but typically reduces performance by a factor of 3.

vertexSplitQuadraticBasisSpline

VSQBS interpolation. Prevents "staircasing" when enlarging.

versions

An Object containing the version numbers of libvips and its dependencies.

Examples

console.log(sharp.versions);

cache

Gets or, when options are provided, sets the limits of libvips' operation cache. Existing entries in the cache will be trimmed after any change in limits. This method always returns cache statistics, useful for determining how much working memory is required for a particular task.

Parameters

• options (Object | boolean) Object with the following attributes, or boolean where true uses default cache settings and false removes all caching (optional, default true)
  • options.memory number is the maximum memory in MB to use for this cache (optional, default 50)
  • options.files number is the maximum number of files to hold open (optional, default 20)
  • options.items number is the maximum number of operations to cache (optional, default 100)

Examples

const stats = sharp.cache();

sharp.cache( { items: 200 } );
sharp.cache( { files: 0 } );
sharp.cache(false);

Returns Object

concurrency

Gets or, when a concurrency is provided, sets the number of threads libvips' should create to process each image.

The default value is the number of CPU cores, except when using glibc-based Linux without jemalloc, where the default is 1 to help reduce memory fragmentation.

A value of 0 will reset this to the number of CPU cores.

The maximum number of images that can be processed in parallel is limited by libuv's UV_THREADPOOL_SIZE environment variable.

This method always returns the current concurrency.

Parameters

• concurrency number?

Examples

const threads = sharp.concurrency(); // 4
sharp.concurrency(2); // 2
sharp.concurrency(0); // 4

Returns number concurrency

queue

An EventEmitter that emits a change event when a task is either:

• queued, waiting for libuv to provide a worker thread
• complete

Examples

sharp.queue.on('change', function(queueLength) {
  console.log('Queue contains ' + queueLength + ' task(s)');
});

counters

Provides access to internal task counters.

• queue is the number of tasks this module has queued waiting for libuv to provide a worker thread from its pool.
• process is the number of resize tasks currently being processed.

Examples

const counters = sharp.counters(); // { queue: 2, process: 4 }

Returns Object

simd

Get and set use of SIMD vector unit instructions. Requires libvips to have been compiled with liborc support.

Improves the performance of resize, blur and sharpen operations by taking advantage of the SIMD vector unit of the CPU, e.g. Intel SSE and ARM NEON.

Parameters

• simd boolean (optional, default true)

Examples

const simd = sharp.simd();
// simd is `true` if the runtime use of liborc is currently enabled

const simd = sharp.simd(false);
// prevent libvips from using liborc at runtime

Returns boolean