Images

Transform and optimize images with the Cloudflare Images binding.

The Images binding optimizes and manipulates images directly in a Worker — resize, transform, overlay, and re-encode raw image bytes from any source, including a request body, R2, or a fetch response. The exp/cloudflare/images package wraps it.

Declare the binding

[images]
binding = "IMAGES"

Resolve the binding

images.NewImagesBinding resolves the binding by name and returns an error when no binding with that name exists.

import "github.com/syumai/workers-go/exp/cloudflare/images"

img, err := images.NewImagesBinding("IMAGES")
if err != nil {
	// no binding named IMAGES
}

Transform an image

Input takes the image bytes as an io.Reader and returns an *ImageTransformer. Chain Transform calls, then Output picks the output format and returns an *ImageTransformationResult.

transformer, err := img.Input(req.Body, images.ImageInputOptions{})
if err != nil {
	return nil, err
}
transformer, err = transformer.Transform(images.ImageTransform{
	Width:  300,
	Height: 300,
	Fit:    "cover",
})
if err != nil {
	return nil, err
}
result, err := transformer.Output(images.ImageOutputOptions{Format: "image/avif"})
if err != nil {
	return nil, err
}

ImageTransform also supports Blur, Brightness, Contrast, Gamma, Rotate, Saturation, Sharpen, Flip, Gravity, Border, and more.

Draw overlays a second image — e.g. a watermark read from R2 — at a given position. Composite selects the compositing mode (images.ImageCompositeModeOver and friends).

transformer, err = transformer.Draw(watermark, images.ImageDrawOptions{
	Top:     10,
	Left:    10,
	Opacity: 0.8,
})

Return the result

HTTPResponse converts the result into an *http.Response, ready to return from a workers.Serve handler.

return result.HTTPResponse()

Alternatively, Image streams the output bytes as an io.ReadCloser, ContentType returns the result’s media type, and Response returns the raw JS Response — pass ImageTransformationResponseOptions to attach extra headers.

Info reads an image’s metadata without transforming it:

info, err := img.Info(imageBytes, images.ImageInputOptions{})
fmt.Println(info.Format, info.Width, info.Height)