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https://github.com/storytold/pdfcraft.git
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Guillem Hermida
359a3f2f09
Optimize decoded DCT images with the generic JPEG decoder, which converts three components from YCbCr to RGB whenever the JPEG itself doesn't say otherwise, and then dropped /DecodeParms. An RGB JPEG stored untransformed (/ColorTransform 0 and no Adobe marker) therefore came out in other colours when recompressed, resampled or merged from strips. The samples are now read with the colour transform ISO 32000-2 §7.4.8 gives them: an Adobe APP14 marker's flag, else /ColorTransform (default 1). Untransformed samples are taken as stored, and the result is written as a plain YCbCr JPEG (or Flate), which needs no /DecodeParms. When the marker and /ColorTransform disagree, a value is out of range, the parameters are not paired with the filter as §7.4 pairs them, or the decoder reads the components otherwise (named R, G and B), the image is left as it is. The tests draw each image with PdfCraft's renderer before and after Optimize: RGB JPEGs with and without an Adobe marker under each /ColorTransform, CMYK JPEGs (still left alone) and JPEG strips merged into one picture. Part of #1201.
26 lines
823 B
TOML
26 lines
823 B
TOML
[package]
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name = "pdfcraft-optimize"
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description = "The PDF Optimizer: image downsampling and recompression, discarding objects, clean-up"
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version.workspace = true
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edition.workspace = true
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license.workspace = true
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rust-version.workspace = true
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repository.workspace = true
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[lints]
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workspace = true
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[dependencies]
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pdfcraft-cos = { workspace = true }
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pdfcraft-content = { workspace = true }
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pdfcraft-model = { workspace = true }
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pdfcraft-annot = { workspace = true }
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thiserror.workspace = true
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# JPEG decoding (zune-jpeg) and encoding, and bicubic resampling; already in the tree.
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image = { version = "0.25", default-features = false, features = ["jpeg"] }
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# The same JPEG decoder, used directly to read samples untransformed (/ColorTransform 0).
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zune-jpeg = "0.5"
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[dev-dependencies]
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pdfcraft-render = { workspace = true }
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