width (w)

This parameter sets width of output image. w is an alias for this parameter.

If this parameter is omitted, and the height parameter is set, the output width is set automatically such that aspect ratio is preserved. If both height and width parameters are set, the output image dimensions are set as per mode parameter.

If none of the height and width parameters are set, original aspect ratio is preserved and output dimensions depend on parameters like scale if provided.

Maximum value for this is 8192 and any output which has more than this width will be scaled down to this value.

width=250	Original

height (h)

This parameter sets height of output image. h is an alias for this parameter.

If this parameter is omitted, and the width parameter is set, the output height is set automatically such that aspect ratio is preserved. If both height and width parameters are set, the output image dimensions are set as per mode setting.

If none of the height and width parameters are set, original aspect ratio is preserved and output dimensions depend on parameters like scale if provided.

Maximum value for this is 8192 and any output which has more than this height will be scaled down to this value.

height=250	Original

dpr

Specifies device pixel ratio. Valid values are between 1.0 and 3.0 and floating point numbers are valid parameters. This acts as multiplier to both width and height. width=200&height=300&dpr=2 is equivalent to width=400&height=600.

This makes it easy to specify image with correct resolution when using srcset attribute of <img> tag.

enlarge

This boolean parameter specifies whether the output image should be enlarged if input image dimensions are smaller than required dimensions.

For example, if input image width is 800px wide and width=1000 is specified, the output image will still remain 800px. If enlarge=true is set then only the output image will have 1000px width.

Default value of this parameter is false if mode is crop or stretch and true otherwise. You can't override the default false if mode is set to crop or stretch

mode

Specifies the resize behavior when width or height parameters are provided.

fit: Resize to fit within boundaries specified by width and height parameters. If ratio given differs from original aspect ratio, only one dimension will be set as per given value and other dimension will be smaller such that original aspect ratio is maintained.
crop: Entire area defined is filled maintaining aspect ratio but might crop part of image. The type of cropping is determined by crop parameter.
stretch: Resize to fill area defined by height and width. It might not preserve aspect ratio and image might be distorted.
min: Preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to the width and height specified.
max: Preserving aspect ratio, resize the image to be as large as possible while ensuring its dimensions are less than or equal to the width and height specified.
fill: Preserving aspect ratio, resize the image to the maximum width or height specified then embed on a background of the exact width and height as original image. You can fill excess space with fill parameter.
fillmax: Resize the image by preserving the aspect ratio and without stretching the original image. If the requested width or height exceeds the original, it will fill the space with a solid color or blurred version of the image, based on fill parameter value.

Default mode is fit.

mode=fit	mode=crop	mode=stretch

fill

This parameter specifies how to fill the extra space created by mode=fill.

solid Fills excess space with solid color specified by parameter fill-color. If fill-color is not specified then access space will be filled with white.
blur Fills excess space with the blurred original image.
background Fills excess space with top-left corner colour.

Default value of this parameter is solid.

mode=fill&fill=background	mode=fill&fill=solid&fill-color=c0c0c0	mode=fill&fill=blur

fill=blur options

With fill=blur, you can pass the intensity of the blur. The value ranges from 1 to 100.

mode=fill&fill=blur&fill-blur=10	mode=fill&fill=blur&fill-blur=100

crop

Allows you to define crop position when using crop as mode parameter.

Valid values are entropy, smart, top, topleft, left, bottomleft, bottom, bottomright, right, topright , faces, center and focalpoint.

While other modes are self explanatory, let us describe first some special crop modes.

faces: detects all faces in an image and tries to keep them in center in cropped image.

mode=crop&crop=faces	original

entropy: focus on region with highest Shanon Entropy.
smart: focus on region with highest luminance frequency and skin tones. Gumlet automatically finds person or other objects in image and keeps them in center while cropping.
focalpoint: focus on point given by you. It allows you to define the point of focus by fp-x and fp-y. You can also define zoom using fp-z. fp-x and fp-y must be float value between 0.0 to 1.0 and default value will be 0.5. fp-z can be in the range of 1 to 10 and default value is 1.

Default mode if no parameter is provided is center.

mode=crop	mode=crop&crop=smart	mode=crop&crop=focalpoint

mask

It mask the image as per the given input. current supported mask shapes are ellipse and corners.

ellipse Mask image into ellipse shape. When masked image is output as a PNG, masked area will be transparent otherwise it will be the default background. To get the circle shape with mask, the output image must have the same width and height otherwise it will be oval.
cornersMask the corner of the image rounded. One can control it using therpixelsparameter by providing a pixel value that needs to be rounded.

mask=ellipse	mask=corners	original

extract (rect)

Extract a region from image. rect is an alias for this parameter. This operation is always applied before resize operation. Please give the parameters according to original image.

The value should be provided as comma separated list left,top,width,height.

left is zero-indexed offset from left edge
top is zero-indexed offset from top edge
width of extracted image
height of extracted image

extract=0,0,300,300	extract=300,300,200,200	original

aspect ratio (ar)

Resize and crop the image to given aspect ratio. This parameter will work only with mode=crop. ar is proportional representation between width and height.

E.g. ar=3:4&mode=crop will crop image in aspect ratio of 3:4. You can add one dimension (height or width) along with ar and other dimension will be automatically calculated based on aspect ratio. height=400&ar=3:4&mode=crop here width 300 will be automatically calculated.

height=400&ar=3:4&mode=crop	ar=1:1&mode=crop&crop=smart	original

pad

Pads/Extends the edges of the image with the color provided by the background parameter. The value should either be integer which adds padding of same number of pixel to all edges or it should be comma separated list of 4 integers as top,right,bottom,left.

E.g. pad=40,20,40,30 will add 40px padding on top, 20px on right, 40px on bottom and 30px on left. If you want to add same padding to all sides, you can provide just one number like pad=40 and it will add 40px on all sides.

Please note this operation will add additional pixels and hence increase height and width of image. This operation is applied after resize. Please provide padding parameters accordingly.

pad=30,30,30,30&bg=b03e5c	original

trim

Trim "boring" pixels from all edges that contain values within a percentage similarity of the top-left pixel. The value of this parameter is number between 1 to 99 representing the percentage similarity.

This operation is applied after resize.

If you want to match a custom color and not use the top-left pixel, you can pass a hex color code by using trim-color parameter. For example trim=10&trim-color=fafafa.

trim=50	original

dpi

Dots per inch (DPI) specifies how should we convert SVG or PDF files which are vector images to raster images like JPEG. Higher the parameter, bigger the default output sizes will be.

Default value is 72.