ee-image-worker

ee-image

smart, smooth & fast image resizing and cropping

the library is currently rewritten and under development

installation

npm install ee-image-worker

#Usage U can either create an image or a transformation. An image is basically a transformation bound to data (the original buffer). Instantiate the two using the factory methods:

    var eeImage = require('ee-image-worker');
    var trans = eeImage.createTransformation();
    var image = eeImage.createImage(buffer);

Future versions will allow you to inject a processing engine to the factory.

#Basic interface Both enitities support the following interface (fluent):

##pad(color, left, [ upper ]) Adds padding around the image. The color will be converted to the color format of the image.

• color an array consisting of byte values e.g. [0x00, 0x00, 0x00] for rgb black
• left if left is specified as a number it is applied to the left and the right side of the image, left can also be an object of the form {left, right, top, bottom} (then the upper value is ignored)
• upper if upper is specified as a number it is applied to the top and bottom of the image

##crop(width, height, [ offsets ]) Crops the image to width and height. - width number - height number - offsets {top, left, bottom, right} (all are optional, left and top have higher priority)

##resize(width, height, [ filter ]) Resizes the image to the specified dimensions. - width number - height number - filter string ('lanczos', 'catmulrom', 'cubic' ... see picha)

##scale(dimensions, [ mode ]) Represents specific resizing and cropping actions - dimensions an object {width: number, height: number} for the default mode (resize) you can omit one of them and it is resized proportionally - mode string, the specific mode - crop covers the passed dimensions and crops off overlapping data - fit fits the image into the bounds proportionally without removing data - resize resizing (proportionally if with or height is omitted)

#Transformations

• toJpeg(buffer, [options], callback), toPng, toWebp, toTiff (adds a temporary encoding)
• encode(format, options) this is permanent
• applyTo(buffer, callback)

#Image

• toBuffer(format, options, callback)
• toJpeg([options], callback), toPng, toWebp, toTiff (adds a temporary encoding)

#Appendix The library will be rewritten to support new features.

Focus by default is at the center of the image and will be adjusted according to the chosen strategy.

##Supported image formats Support depends on the installed libraries

• jpeg
• png
• tiff
• webp

No .gif support!

##Error handling To have a consistent error handling we'll wrap picha's errors.

###Unsupported image file Can be because of an unexpected Buffer format, or a missing library (such as libwebp). We'll probably have to check this upfront. Introduce error codes to distinguish properly.

##Strategies We differentiate two image resizing types:

• resize(width, height, filter) applies a change of dimension without taking the image dimensions into account any precomputations
• scale(width, height, strategy, options) applies a change of dimension following a specific strategy. Strategies can be one of the following
  • resize is an ordinary resizing
  • fit scales the image to fit into a bounding box
  • fill scales and crops an image to fill a bounding box
  • carve applies seam carving

##Face detection To detect faces is not as easy as we thought. So i propose a combination of multiple detections (faces and eyes): First group all faces that somehow intersect (drop all faces that have no intersection, this might kills some good results).