Image version 0.70.0

Added

• Adds Image.Lqip.Css to encode an image as a packed LQIP CSS placeholder value, with a new guide including the copy-and-paste stylesheet. Thanks to @hlindset for the PR.

• Adds Image.BackgroundColor to resolve background color specifications (including :average) into concrete pixels; used by Image.rotate/3, affine and warp operations. Thanks to @hlindset for the PRs.

• Adds :background color resolution to Image.write/3 so alpha images flatten onto a resolved background when writing to formats without alpha. Thanks to @hlindset for the PR.

• Adds Image.YUV.valid_encodings/0 and Image.YUV.valid_colorspaces/0.

Changed

• Image.average/1 now weights the average by the alpha band so transparent pixels do not contribute; fully transparent images fall back to the unweighted color-band average, and float-format images return unrounded averages.

• All validation and libvips errors are now returned as {:error, %Image.Error{}} as t:Image.error/0 documents; previously many paths returned bare strings.

• Image.to_nx/2 with shape: :whc now performs a true transpose; Image.from_nx/1 interprets unnamed tensors as {height, width, bands} and narrows 64-bit integer tensors to 32 bits.

• Image.circle/2 center-crops non-square images and merges an existing alpha band instead of adding a second one.

• Image.embed/4 honors :mirror/:repeat/:copy extend modes and explicit background colors on images with an alpha band.

• Image.compose/3 with a composition list applies top-level options as per-entry defaults instead of ignoring them.

• Image.join/2 accepts the documented :top and :center alignment values.

Fixed

• Fix the alpha scale for :lab, :lch and :labs interpretations in Image.Pixel.to_pixel/3 — opaque alpha is 255, matching libvips. Thanks to @hlindset for the PR.

• Fix Image.Math.divide/2 for two numbers (it previously subtracted) and Image.dominant_color/2 black-bin correction for alpha images.

• Fix Image.Draw functions on greyscale and CMYK images, Image.Shape.line/5 end coordinate, and Image.Shape.star/2 accepting 3 points as documented.

• Fix crashes on malformed EXIF payloads, non-base83 blurhash input, GIF writes with :effort, extensionless write paths, and Image.stream!/2 with small :buffer_size values.

• Fix Image.YUV round trips for odd image dimensions and Image.trim/2 with an explicit :background on alpha images.

• Fix Image.thumbnail!/3 and Image.straighten_perspective/3 error contracts, Image.from_req_stream/2 timeout handling, and Image.equalize/2 on constant-color bands.

• Fix Image.write/3 to a t:File.Stream.t/0 to infer the image type from the stream path's file extension when no :suffix option is given.