FilterJS

An image filtering library built on top of Jimp incorporating much of the image manipulation functionality of CamanJS including the preset filters implemented therein.

As with Jimp, supports: jpeg, png, bmp, tiff, gif.

Installation

npm install --save @harikulendran/filterjs

Basic Usage

``javascript
var FJS = new FilterJS();
var filteredBase64 = await FJS.apply(inputBase64, {name:'filterName'});
var filteredBase64 = await FJS.apply(inputPath, {name:'filterName'}, "path");
`
Apply a filter 'filterName' to an image, either from a path or from a base 64 representation and return a promise for the base 64 representation of the filtered image.

Custom Filters

Custom filters can be passed to the apply method like so:

`javascript
var filter = {
name: 'customFilterName', //Name must not clash with existing filters
instructions: [
...
]
};
`

$3

Instructions are made up of layers and functions, layers allow you to composite multiple lists of functions onto each other, and functions modify image data. For example a basic filter that increases brightness would be defined as:

`javascript
var brightenFilter = {
name: 'brightenFilter',
instructions:
{ layer:'base', idx:0, blend:'', instructions: [
{ apply:'brightness', params:[0.5] } //Parameters must be enclosed in an array
]}
]
};
`

$3

A layer is comprised of a type, an index, and blend mode and a set of instructions, the types are defined as such:

`javascript
layer: 'base' <- the base image, onto which all layers are composited
'clone' <- a layer created by cloning another layer (specified in the cl param)
'blank' <- a blank layer
`
The index, idx is used to define the order of the layers. An additional cl parameter is given when creating a clone layer, this is to let FilterJS know which layer to clone from.

The supported blend modes are from Jimp and can be found here.

$3


The instructions argument takes a list of functions to apply to the layer, all of the Jimp operations are support (listed here), and are converted into the correct syntax as such:

`javascript
image.posterize( n ); => { apply:'posterize', params:[n] }

image.color([ { apply:'color', params: [
{ apply: 'red', params:[10] } => { apply: 'red', params:[10] }
]); ]}
`

On top of these functions, FilterJS also supports/overrides the following:

`javascript
//Adjust the gamma
{apply:'gamma', params:[amt]}

//Apply curves, clipped at max and min, and applied to the selected channels
{apply:'curves', params:[start, c1, c2, end, min, max, ch]}

//Adjust the exposure
{apply:'exposure', params:[amt]}

//Add noise with the given strength
{apply:'noise', params:[amt]}

//Adjust the vibrance
{apply:'vibrance', params:[amt]}

//Sharpen the image
{apply:'sharpen', params:[amt]}

//Apply a vignette to the given percentage of the given strength
{apply:'vignette', params:[p, str]}

//Apply sepia
{apply:'sepia', params:[amt]}

//Colorise the image
{apply:'colorise', params:[amt]}

//Fill the image with a given colour
{apply:'fill', params:[rgb]}

//Clip the image on both extremes by the given amount
{apply:'clip', params:[amt]}
``

Preset Filters

FilterJS supports all the preset filters implemented in CamanJS:

* Vintage
* Lomo
* Clarity
* Sin City
* Sunrise
* Cross Process
* Orange Peel
* Love
* Grungy
* Jarques
* Pinhole
* Old Boot
* Glowing Sun
* Hazy Days
* Her Majesty
* Nostalgia
* Hemingway
* Concentrate