gatsby-plugin-sharp
Exposes several image processing functions built on the Sharp image processing library. This is a low-level helper plugin generally used by other Gatsby plugins. You generally shouldn’t be using this directly but might find it helpful if doing very custom image processing.
It aims to provide excellent out-of-the box settings for processing common web image formats.
For JPEGs it generates progressive images with a default quality level of 50.
For PNGs it uses pngquant to compress
images. By default it uses a quality setting of [50-75]. The pngCompressionSpeed
value is a speed/quality trade-off from 1 (brute-force) to 10 (fastest). Speed
10 has 5% lower quality, but is 8 times faster than the default (4). In most
cases you should stick with the default, but if you have very large numbers
of PNGs then it can significantly reduce build times.
Install
npm install gatsby-plugin-sharp
How to use
// In your gatsby-config.js
plugins: [
{
resolve: `gatsby-plugin-sharp`,
options: {
// Defaults used for gatsbyImageData and StaticImage
defaults: {},
// Set to none to allow builds to continue on image errors
failOn: `none`,
// deprecated options and their defaults:
base64Width: 20,
forceBase64Format: ``, // valid formats: png,jpg,webp
useMozJpeg: process.env.GATSBY_JPEG_ENCODER === `MOZJPEG`,
stripMetadata: true,
defaultQuality: 50,
},
},
]
Options
defaults
: default values used forgatsbyImageData
andStaticImage
from gatsby-plugin-image. Available options are:formats
,placeholder
,quality
,breakpoints
,backgroundColor
,tracedSVGOptions
,blurredOptions
,jpgOptions
,pngOptions
,webpOptions
,avifOptions
. For details of these, see the reference guide.failOn
: default =warning
. By default builds will fail if there is a corrupted image. Set tonone
to continue the build on error. The image will returnundefined
. You can customize this option, seeoptions.failOn
.
Other options are deprecated, and should only be used for the legacy fixed
and fluid
functions.
Methods
resize
Parameters
width
(int, default: 400)height
(int)quality
(int, default: 50)jpegQuality
(int)pngQuality
(int)webpQuality
(int)jpegProgressive
(bool, default: true)pngCompressionLevel
(int, default: 9)base64
(bool, default: false)
Returns
src
(string)width
(int)height
(int)aspectRatio
(float)
fixed
Automatically create sizes for different resolutions — we do 1x, 1.5x, and 2x.
Parameters
width
(int, default: 400)height
(int)quality
(int, default: 50)jpegQuality
(int)pngQuality
(int)webpQuality
(int)
Returns
base64
(string)aspectRatio
(float)width
(float)height
(float)src
(string)srcSet
(string)
fluid
Create fluid sizes (in width) for the image. If the max width of the container for the rendered markdown file is 800px, the sizes would then be: 200px, 400px, 800px, 1200px, 1600px – enough to provide close to the optimal image size for every device size / screen resolution.
If you want more control over which sizes are output you can use the srcSetBreakpoints
parameter. For example, if you want images that are 200, 340, 520, and 890 wide you
can add srcSetBreakpoints: [ 200, 340, 520, 890 ]
as a parameter. You will also get
maxWidth
as a breakpoint (which is 800 by default), so you will actually get
[ 200, 340, 520, 800, 890 ]
as breakpoints.
On top of that, fluid
returns everything else (namely aspectRatio and
a base64 image to use as a placeholder) you need to implement the “blur up”
technique popularized by Medium and Facebook (and also available as a Gatsby
plugin for Markdown content as gatsby-remark-images).
When both a maxWidth
and maxHeight
are provided, sharp will resize the image using
COVER
as a fit strategy by default. You can choose between COVER
, CONTAIN
, FILL
,
INSIDE
, and OUTSIDE
as a fit strategy. See the fit parameter below
for more details.
Parameters
maxWidth
(int, default: 800)maxHeight
(int)quality
(int, default: 50)jpegQuality
(int)pngQuality
(int)webpQuality
(int)srcSetBreakpoints
(array of int, default: [])background
(string, default: ‘rgba(0,0,0,1)‘)
Returns
base64
(string)aspectRatio
(float)src
(string)srcSet
(string)srcSetType
(string)sizes
(string)originalImg
(string)
Shared Options
In addition to their individual parameters, all methods above share the following:
grayscale
(bool, default: false)duotone
(bool|obj, default: false)toFormat
(string, default: ”)toFormatBase64
(string, default: ”)base64Width
(int, default: 20)cropFocus
(string, default: ‘ATTENTION’)fit
(string, default: ‘COVER’)pngCompressionSpeed
(int, default: 4)rotate
(int, default: 0)
toFormat
Convert the source image to one of the following available options: NO_CHANGE
,
JPG
, PNG
, WEBP
.
toFormatBase64
base64 image uses the image format from the source, or the value of toFormat
. This setting allows a different image format instead, available options are: JPG
, PNG
, WEBP
.
WEBP
allows for a smaller data size, allowing you to reduce your HTML size when transferring over the network, or to use a larger base64 placeholder width default for improved image placeholder quality.
Not all browsers support WEBP
. It would be wasteful to include a fallback image format in this case. Consider also adding a backgroundColor
placeholder as a fallback instead.
The plugin config option forceBase64Format
performs the equivalent functionality by default to all your base64 placeholders. toFormatBase64
has a higher priority for base64 images that need to selectively use a different format.
base64Width
The width in pixels for your base64 placeholder to use. The height will also be adjusted based on the aspect ratio of the image. Use this to increase the image quality by allowing more pixels to be used at the expense of increasing the file size of the data to be transferred.
The default for Gatsby is 20
px. This keeps the data size low enough to embed into the HTML document for immediate display on DOM loaded and avoids an additional network request.
Facebook and Medium are both known to use 42
px width for their image placeholders. However Medium presently uses a solid background color placeholder to load the page as fast as possible, followed by an image placeholder requested over the network instead of embedding it with base64.
The plugin config has an equivalent option, allowing you to change the default for all base64 placeholders. This parameter option has a higher priority over the plugin config option.
cropFocus
Change the cropping focus. Available options: CENTER
, NORTH
, NORTHEAST
,
EAST
, SOUTHEAST
, SOUTH
, SOUTHWEST
, WEST
, NORTHWEST
, ENTROPY
,
ATTENTION
. See Sharp’s resize.
fit
Select the fit strategy for sharp to use when resizing images. Available options
are: COVER
, CONTAIN
, FILL
, INSIDE
, OUTSIDE
. See Sharp’s resize.
Note: The fit strategies CONTAIN
and FILL
will not work when cropFocus
is
set to ENTROPY
or ATTENTION
.
The following image shows the effects of each fit option. You can see that the
INSIDE
option results in one dimension being smaller than requested, while
the OUTSIDE
option results in one dimension being larger than requested.
pngCompressionSpeed
Change the speed/quality tradeoff for PNG compression from 1 (brute-force) to 10 (fastest). See pngquant’s options.
rotate
Rotate the image (after cropping). See Sharp’s rotate.
grayscale
Uses Sharp’s greyscale to convert the source image to 8-bit greyscale, 256 shades of grey, e.g.
allImageSharp {
edges {
node {
... on ImageSharp {
resize(width: 150, height: 150, grayscale: true) {
src
}
}
}
}
}
duotone
Applys a “duotone” effect (see I, II, III) to the source image if
given two hex colors shadow
and highlight
defining start and end color of
the duotone gradient, e.g.
fixed(
width: 800,
duotone: {
highlight: "#f00e2e",
shadow: "#192550"
}
) {
src
srcSet
base64
}
the source image colors will be converted to match a gradient color chosen based
on each pixel’s relative luminance.
Logic is borrowed from react-duotone.
You can pass a third optional parameter, opacity
:
fluid(
width: 800,
duotone: {
highlight: "#f00e2e",
shadow: "#192550",
opacity: 50
}
) {
src
srcSet
base64
}
If set, a semi-transparent version of duotone’d image will be composited over the original image, allowing the original image and its colors to partially “shine through”. Heads up: If the original image contains an alpha channel it will be flattened before creating the composite.
This works by adding an alpha channel to the duotone’d image - then we let Sharp
do its magic via
overlayWith
;
quoting the Sharp documentation:
If the overlay image contains an alpha channel then composition with premultiplication will occur.
tracedSVG
Generates a traced SVG of the image (see the original GitHub issue) and
returns the SVG as ”optimized URL-encoded” data:
URI. It used in
gatsby-image to provide an
alternative to the default inline base64 placeholder image.
Uses node-potrace and SVGO under the hood. Default settings for node-potrace:
{
color: `lightgray`,
optTolerance: 0.4,
turdSize: 100,
turnPolicy: TURNPOLICY_MAJORITY,
}
All node-potrace Potrace
parameters are exposed and can be set via the
traceSVG
argument:
fixed(
traceSVG: {
color: "#f00e2e"
turnPolicy: TURNPOLICY_MINORITY
blackOnWhite: false
}
) {
src
srcSet
tracedSVG
}
Setting a default quality
You can pass a default image quality to sharp
by setting the defaultQuality
option.
Using MozJPEG
You can opt-in to use MozJPEG for jpeg-encoding. MozJPEG provides even
better image compression than the default encoder used in gatsby-plugin-sharp
.
However, when using MozJPEG the build time of your Gatsby project will increase
significantly.
To enable MozJPEG, you can set the useMozJpeg
plugin option to true
in
gatsby-config.js
.
For backwards compatible reasons, if useMozJpeg
is not defined in the plugin
options, the environment variable
GATSBY_JPEG_ENCODER
acts as a fallback if set to MOZJPEG
:
GATSBY_JPEG_ENCODER=MOZJPEG
Allow build to continue on image processing error
By default, the build will fail when it encounters an error while processing an image. You can change this so that
it continues the build process by setting the plugin option failOn
to none
. Sharp will still throw an error and
display it in the console as a GraphQL error, but it will not exit the process. It is important to note that any images that would have otherwise failed will not be accessible via childImageSharp
until the underlying issue with the image is addressed.
EXIF and ICC metadata
By default, gatsby-plugin-sharp
strips all EXIF, ICC and other metadata
present in your source file. This is the recommended default as it leads to
smaller file sizes.
However, in situations where you wish to preserve EXIF metadata or ICC profiles
(example: you are building a photography portfolio and wish to conserve
the color profile or the copyright information of the photos you’ve exported
from Adobe Lightroom or Phase One’s Capture One), you can set the stripMetadata
plugin option to false
in gatsby-config.js
.
It is important to note that if stripMetadata
is set to false
, all
metadata information will be preserved from the source image, including but not
limited to the latitude/longitude information of where the picture was taken
(if present). If you wish to strip this information from the source file, you
can either leave stripMetadata
to its default of true
, or manually
pre-process your images with a tool such as ExifTool.
Troubleshooting
Incompatible library version: sharp.node requires version X or later, but Z provides version Y
This means that there are multiple incompatible versions of the sharp
package installed in node_modules
. The complete error typically looks like this:
Something went wrong installing the "sharp" module
dlopen(/Users/misiek/dev/gatsby-starter-blog/node_modules/sharp/build/Release/sharp.node, 1): Library not loaded: @rpath/libglib-2.0.dylib
Referenced from: /Users/misiek/dev/gatsby-starter-blog/node_modules/sharp/build/Release/sharp.node
Reason: Incompatible library version: sharp.node requires version 6001.0.0 or later, but libglib-2.0.dylib provides version 5801.0.0
To fix this, you’ll need to update all Gatsby plugins in the current project that depend on the sharp
package. Here’s a list of official plugins that you might need to update in case your projects uses them:
gatsby-plugin-sharp
gatsby-plugin-manifest
gatsby-remark-images-contentful
gatsby-source-contentful
gatsby-transformer-sharp
gatsby-transformer-sqip
To update these packages, run:
npm install gatsby-plugin-sharp gatsby-plugin-manifest gatsby-remark-images-contentful gatsby-source-contentful gatsby-transformer-sharp gatsby-transformer-sqip
If updating these doesn’t fix the issue, your project probably uses other plugins from the community that depend on a different version of sharp
. Try running npm list sharp
or yarn why sharp
to see all packages in the current project that use sharp
and try updating them as well.