From CodeRabbit's review of the stack:
- Every JBIG2 image read its /JBIG2Globals afresh, within 32 MiB each but with no
bound across an export or a redaction. A globals stream of the file, not edited since
it was read and with its /DecodeParms direct, now has its filters undone once a
document and is kept for the images that share it (in every clone, which share the
file), up to 64 MiB in all. An edited one, one added in memory, or one with
/DecodeParms by reference (another object, which can change under it) is read each
time as before. This saves the filters only: the decoder reads the segments afresh for
every image, so a real symbol dictionary still costs its decoding once an image.
- view.copy-image dropped "JBIG2 inside other filters" from its missing list on the
strength of Export's test; Copy Image now has its own: a JBIG2 picture behind
ASCIIHexDecode is found under the pointer and copied as its pixels and as a PNG, and
one whose page information is in its globals is read through them.
A JBIG2 image's /Width and /Height are read as given directly; one by reference is an
error rather than an image of no rows.
A /JBIG2Globals reference to no object still reads as no globals: it is a reference
to null (ISO 32000-2 §7.3.10), which an entry may hold for being absent (§7.3.7), and
the renderer draws the page so. An image that needed those globals then mostly fails
to decode; in a probe of twelve pictures that decoded with them, eleven were refused
and one decoded to other pixels.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AmsdeUCdTaD72jkDw2pJKY
#5461 made Document::decoded_image read JBIG2, page exactly the image's size, and
kept the optimizer's monochrome step off it until it could weigh JBIG2 again. Now
one_bit reads JBIG2 last after any filters, within the raster's allowance, and mono
treats it as it does any black-and-white image:
- above the threshold it is averaged, and stored as the compression asks, the
smallest of what that may store; under Retain it is stored as JBIG2 again, its kind
of compression kept;
- not resampled, it is stored again as the compression asks when that is smaller: a
generic region becomes symbols with JBIG2 asked for, and JBIG2 behind ASCIIHex is
stored again alone (as Group 4 where that is smaller);
- a JBIG2 image stored again refers to no /JBIG2Globals; one whose page isn't its
size isn't read, and stays.
jbig2_images_are_left_as_they_are becomes jbig2_scans_are_averaged_and_stored_again:
a JBIG2 scan at 600 ppi, alone, behind ASCIIHex and with globals, averages to the
same samples as its Flate copy under each compression (Retain keeping JBIG2); at 300
ppi a generic region of rendered text stays under Group 4 (larger) and Retain and
becomes symbols under JBIG2 (under half the size); behind ASCIIHex it is stored again
alone, as Group 4 where the hex is spaced out; a taller page stays.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
#5426 left indexed images at their resolution rather than guess which sample is
dark. The palette says: dark_is_one now maps samples 0 and 1 through the decode array
to palette entries (rounded and clipped to hival, ISO 32000-2 §8.9.5.2) and compares
how light those entries are (`lightness`: the grey, or Rec. 601 luma over DeviceRGB).
Only DeviceGray and DeviceRGB bases count, the table a string or a stream (within
4 KiB), directly or by reference: there the palette's values are the colour, and
under /DefaultGray or /DefaultRGB no polarity is asked for. Other bases (CMYK,
calibrated, ICC-based, a resource name), two entries alike, an entry the table
doesn't hold or a hival past 255 still say nothing; separations and DeviceN still
aren't averaged, their tint transforms unread. #5426's tone guard applies as to any
image.
#5426's indexed thin-rule test now checks what it was for: with the palette either
way round and the decode array either way, the averaged image holds the averaged
DeviceGray one's samples (flipped where its samples are) and renders the same. A unit
test covers each base, both orders, an inverting decode array, the weights of luma,
the table by reference and in a stream, and every refusal; the older polarity test's
doc says what is known now.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Part of #283. A scan stored as JBIG2 (as the optimizer writes them) is decoded
through Document::decoded_image_within, its /JBIG2Globals included, and its covered
pixels cleared in a Flate copy that refers to no globals, as CCITT fax images are.
Before, any JBIG2 image under a mark was removed whole, blanking the page.
Still removed whole (fail-closed): a JBIG2 page of another size than the image,
which decoded_image refuses (the renderer draws the whole page into the image, so
the rows cleared wouldn't be the ones shown); globals that can't be read; damaged
data; an image claiming more than one bit or one component, even where its rows
take as many bytes; a page far past the image's raster, refused before it is
decoded.
Globals no other image uses leave the file with the original on the full rewrite
(tested); globals another image still uses stay, and the README and parity note say
they may hold the shapes of marks from under the area, not where they were.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
decode_jbig2 sits next to decode_ccitt, through hayro-jbig2 as Export ▸ Images
used it, and shares CCITT's row sink. The JBIG2 page has to be the image's size:
PdfCraft's renderer draws the whole page into the image (black box: a 4-row page
behind /Height 2 fills the image box with all four rows), so the rows of a taller
page aren't the image's. The decoder decodes a page whole, so the page is checked
before it is decoded: that size, within the caller's bound as rows of one bit, and
at most 2^28 pixels (MAX_JBIG2_PIXELS; the decoder keeps a bit a pixel, about 34 MB
there).
Document::decoded_image_within decodes a JBIG2 image as it does a fax image: the
filters before it undone first, then the decoder with the /JBIG2Globals of the
image's own /DecodeParms entry (/Crypt counts in the position; fax_params and the
globals now share last_filter_parms). Globals have a limit of their own,
MAX_JBIG2_GLOBALS (32 MiB, moved from Export), and globals that can't be read are an
error rather than ignored.
Export ▸ Images reads JBIG2 through it, so its own decoder, row sink and DecodeParms
reader go, and hayro-jbig2 leaves pdfcraft-create. JBIG2 behind another filter now
exports, and so copies (Copy Image uses the same function); a page taller than the
image, which Export cut to the image's rows, now skips the image, as one of another
width did. doc_export_all_images' description no longer lists JBIG2 inside other
filters as skipped.
The optimizer's monochrome step read images through decoded_image_within and
relied on JBIG2 failing there: it now leaves JBIG2 images alone explicitly, as
before (a resampled one would come out Flate under Retain), and the README and
parity note list them as not yet handled.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The integration in #5426 made downsampling conservative: dark_is_one answers only for
DeviceGray and image masks (a decode array of two different numbers or none), and not
under /DefaultGray or /DefaultRGB, and a square of four new pixels that each cover both
samples keeps the image at its resolution. The README, the crate docs, mono()'s comment
and the optimize.downsample-images parity note still said separations and indexed
images were averaged, a tie going to full ink or entry 0.
Measured on main: a 600 ppi page of the ragged-text fixture is no longer averaged
(it is with the square guard switched off), so the docs say so.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Includes #4325#1952#4180#2529#4320#4805, preserving their original histories.
Keep paragraph alignment and hard/soft wrap metadata together; retain CCITT/downsampling/RGB ownership guards with bounded JBIG2 export and exact-copy symbol encoding.
Combined interaction regressions added. Validation pending.
Preserve main's continuous text selection, page tools and module split. Carry only this branch's sidebar-focus feature and regression onto main, without resurrecting old common files from criss-cross merge bases. Hosted CI remains required.
Use the unified Format Text panel and current page-input context instead of restoring old monolithic UI code. Preserve main's pointer routing, editor accessibility and preferences; retain colour, save and input regressions. Hosted CI must validate this refreshed head.
Packing makes an RGB image grey for every use at once, but /DefaultGray and
/DefaultRGB were checked only where the walk reads: page content and forms.
An annotation's appearance, a pattern, a Type3 glyph or a soft mask's group
drawing the same image can have other default colour spaces, so its colours
could change there.
The walk now records, by object number, every reference in the resources it
reads (each /XObject entry, drawn or not, an /XObject dictionary under its
resources, resources under a page, page-tree node or form), reading the
resources of every page and of every node above one, each page and node a
root. An image the walk reached stays covered unless an object reachable
from the trailer refers to it, or to an object on its way from a page, other
than through those references, or it is held by one that isn't covered; an
eight-bit DeviceRGB image that isn't covered stays RGB. So resources, an
/XObject dictionary or a form a page shares with an appearance keep it RGB,
as does a reference with another generation, while LibreOffice's layout (one
resources object for a page, its /Pages node, and a form inside it that
names it again) still packs. The scan runs only when packing is on and there
is such an image.
The images drawn or listed where the defaults are in force are kept by
object number too, so one named with another generation there stays RGB.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The optimizer now writes JBIG2 images as a symbol dictionary and text
regions, and Export ▸ Images has to read them back. A page of three
repeated letters, symbol coded (smaller than the generic coding),
exports as its picture. The test is added to create.export-all-images'
parity evidence. Asked for in pre-push review.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
A review found that a dense page came out as a stream PdfCraft's own
renderer refuses, so the page drew blank after optimizing: hayro-jbig2
decodes a text region of at most 10,000 symbol instances, and refuses
32,768 symbols or more. The stream was valid (Poppler decoded it), but
every mark went into one text region and up to 65,536 symbols were kept.
A 300 dpi letter page of the optimizer test's own text crossed it.
A page with more than 10,000 marks is now placed by several text
regions, each over a band of rows and all referring to the one symbol
dictionary, which each region but the last keeps retained (7.2.4). Past
32,767 distinct symbols the image is coded generically.
New tests: 25,000 copies placed by three regions, which decode; the
symbol caps decoded, not just reached; and in the optimizer, a whole
letter page of rendered text that looks the same as JBIG2 symbols (it
drew blank before). The READMEs say "still looked at" for the caps, and
that the scans figure is the six pages' total (20% on one page).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
A second review found two rules tested one way only: a mark 257 tall
(not just wide) is left to the generic region, which also bounds the
bitmap allocated for each mark, and runs joined at the lower-left corner
are one mark. The test now has a 1 x 257 column and an anti-diagonal.
The caps on distinct symbols (65,536) and their pixels (2^24) are tested
at and past them, as the run and row caps are.
The scans figure now names its noise: with 2% or more of the letters'
edge pixels flipped, symbols save at most 8% over the generic region.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
Review found behaviour the tests let break unnoticed (each was a
surviving mutant, and each new test fails on it):
- black padding bits: a run reaching past the row would stop symbol
coding on many scans;
- Annex A's 32-bit range and PREV at exactly 256, where a decision would
go uncoded: coordinates past 4,435 on a 12,000-pixel-wide and a
10,050-row page, and the contexts of 4436's coding;
- marks joined at a corner are one mark; 256 pixels a side is a symbol,
257 is left to the generic region;
- the run and row caps, at and past them.
The roadmap's status line for this change now comes first, and the
"about a third smaller than Group 4 on scans" figure is replaced by what
was measured: 27-33% on the same pages with scan-like noise added.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
pdfcraft_filters::encode_jbig2 stores each distinct mark of a 1-bit
image (8-connected black pixels, at most 256 a side) once, as a symbol
in a symbol dictionary, and places its exact copies with an immediate
lossless text region that refers to it. Larger marks, and in a second
plan marks that occur once, go to a generic region over their box. It
keeps whichever of that and the generic coding (encode_jbig2_generic,
unchanged) is smaller. Only exact copies share a symbol, so the stream
decodes to the same bits.
Written from the JBIG committee's ISO/IEC 14492 Final Committee Draft:
6.4 and 6.5 (text region and symbol dictionary decoding), 7.2, 7.4.2
and 7.4.3 (segment headers and syntax) and Annex A (the integer coders,
checked against its worked example and Table A.1).
On six pages of rendered 300 dpi text the output is 28% of the generic
coding's size and 17% of Group 4's, at about 100 ms a page; hayro-jbig2
and Poppler (pdfimages) both decode it to the original bits. Scans,
whose copies of a letter are seldom identical, gain little: that needs
refinement coding. A dictionary shared between pages (/JBIG2Globals)
is a further step.
The optimizer's Monochrome Images > JBIG2 (lossless) and doc_optimize
mono jbig2 use it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
An image's /JBIG2Globals were decoded with the 1 GiB any stream may decode
to, before the JBIG2 page's size is known, so the page's pixel limit didn't
bound them: a few kilobytes of Flate could make export allocate up to 1 GiB.
They now decode within MAX_GLOBALS (32 MiB); globals past it skip the image,
with the limit in the reason. The test covers one byte over and exactly the
limit, and the image's /DecodeParms direct, by reference and in an array.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
found accepted price.0 (up to the field's last widget), but links,
recalculate and the scripts' getField all take a name as the field or
the fields under it, so a formula reading price.0 got no value and no
order check while the page said nothing was wrong. found now looks
names up the same way; a widget name is flagged as missing until all of
them resolve it (from CodeRabbit's review).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The row gets a red step and a "Missing field" caption, as a loop does; a
red card names the formulas and links to the first, in place of the
all-clear; a script that builds names gets a grey "Unchecked reads"
caption and a note; the summary above the page lists a missing field
among the reads and says so, and says when a script names fields as it
runs. The name and formula lines of a row are sized by their own
right-hand text, so a wide caption no longer cuts the name.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
calculation_order flags MissingField (a field deleted from under a sum, a
typo in notation, a script's getField; a group's name and a widget's
number count as there) and BuiltNames (a getField or AFSimple_Calculate
list built at run time, found as af::Site::Built in the same pass as the
literal names). form_calculation_order gives each field's formula and the
two new issues; form_fields shows a custom Calculate script; the
Calculation order page explains both in its row tooltips.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
docs/architecture.md said every image codec decodes through the
bootstrap renderer; Export ▸ Images decodes CCITT (hayro-ccitt) and JPEG
itself. The progress logs' "(a dithered scan)" sat after "soft mask
counted", as if it described the mask, and so did the
optimize.mono-compression note's "(a dithered scan downsampled to JPEG)".
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
PdfCraft's bootstrap renderer draws byte-aligned Group 3 whose fill ends
each end-of-line code on a byte (as TIFF writes it) as other rows than
decode_ccitt reads (black box, at every /K, with /EndOfLine or not:
mostly the first row, then blank). Redaction cleared pixels in the
picture decode_ccitt reads, so a mark over what PdfCraft showed needn't
cover what was cleared, and content shown blank stayed in the copy. Such
an image (/K 0 or more, /EncodedByteAlign) is now removed whole, as
every CCITT image was before this PR; Group 3 off bytes and Group 4 are
still cleared.
The image's parameters come from Document::fax_params, the reading of a
fax image's /DecodeParms entry that decoded_image already did, now on
its own (it was to come with #4404, which uses it too). The redaction
README, the module doc, the redaction and core.image-filters notes and
the spec parity table's status line and revision row say so, and the
core.image-filters note now records the renderer's misdrawing.
group_3_on_bytes_is_removed_whole_and_other_fax_images_cleared: a white
16 × 2 picture, checked to decode as such, is removed whole on bytes (no
codes; codes at /K 0; at /K 1 with /EncodedByteAlign by reference) and
cleared off bytes and as Group 4 on bytes. It fails without the guard;
cargo-mutants catches every viable mutant of it.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
decode_ccitt reads byte-aligned Group 3 whose data has end-of-line codes
but none before the first row (not as T.4 sends them) on bytes. At /K 0
with the fill ending each code on a byte, about one small picture in
five is then read as other rows; at fax width almost none are, as such
pages come out short and are refused. Export already said so. The
optimizer, when it resamples such an image or stores it again as Group 4
from behind another filter, and redaction, when it clears pixels in one,
write those rows back, and nothing said that.
Black-box, PdfCraft's renderer draws such an image exactly as
decode_ccitt reads it (all 42 misread of 200 seeded pictures, behind
ASCII85Decode too), so the written image is what PdfCraft showed before.
Refusing such data instead (a code after nearly every row but none
first) would also refuse some ordinary Modified Huffman images, whose
rows can meet 11 zeros by chance (0.5 to 5% of small ones in a
black-box probe), so the limit is stated rather than guarded: in
decode_ccitt's doc, the filters, optimize and redact READMEs, and the
core.image-filters and mono-compression notes. The optimize README's and
the mono-compression note's "not yet: Group 3 to Group 4 without
resampling" now say a lone Group 3 image: one behind another filter is
stored again as Group 4.
Also from the review: docs/roadmap.md keeps #4335's status line under
this PR's, rather than replacing it; the filters README's tests and the
core.image-filters evidence name the Group 3 layout test; the filters
crate's description names Group 3 and 4 decoding.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
The optimize crate doc and MonoSettings named only 1-bit, CCITT and
eight-bit grey images; doc_optimize's mono said Group 4 only; the M11
milestone row stopped at Group 4 compression. They now include
downsampling (halftones aside), Group 3 to Group 4, 1-bit Flate, and
black-and-white RGB and indexed images that use only palette entries 0
and 1, packed to one bit. That last isn't "two-entry", as the roadmap and
the downsampling parity note had it: an indexed image packs whatever its
palette's size, when its samples are 0 and 1. The mono-compression note
says byte-aligned Group 3 with end-of-line codes but none before the
first row is stored again as PdfCraft draws it, which at /K 0 may be
other rows than were coded.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
With end-of-line codes, the CCITT decoder picks a bad row up again at
the next code and reports no damage (an invalid code, a row of too many
pixels: probed as a black box), so such an image is stored again as
Group 4 the way it decodes. Without them, damage stops the decoding,
too few rows come out, and the image is left alone. Telling damage
apart would take a Group 3 parser of our own; the optimize README and
the mono-compression parity note say so instead.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
- The optimize README, the crate doc and both parity notes say a
halftone or dither, and an image wider than a fax row, isn't averaged
down.
- The README's "Left alone" list is the colour and grey settings'; image
masks, decode arrays and CCITT go to Monochrome Images now. Its
monochrome "Not yet" names an image's own /SMask or /Mask image again
(only images drawn on a page are visited), as the parity note does;
the parity note's row limit is Group 4's.
- docs/architecture.md says CCITT decodes through pdfcraft-filters for
export, redaction and the optimizer, not only the renderer.
- docs/target-app-parity.md no longer lists monochrome downsampling as
missing.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
- Packed to one bit, black-and-white DeviceRGB became DeviceGray. Where
/DefaultGray or /DefaultRGB is in force (ISO 32000-2 §8.6.5.6), that
drew it otherwise: through DefaultGray as grey, or no longer through
DefaultRGB. The page walk now notes the images drawn, on any use, where
a page's or form's resources (an enclosing one's included) name
either, and those stay RGB. When a use couldn't be followed, every
image counts as such.
- One whose soft mask has a /Matte stays RGB too: the matte has one
number for each of the parent's components, three, and grey has one.
- The optimize README, the mono-compression parity note and doc_reduce's
description said Group 3 to Group 4 wasn't done yet, that only images
packed from eight bits could become Flate, and that the colour space
and decode array always stay. They now match the code.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
Monochrome Images only took eight-bit grey of only black and white
besides 1-bit images, so the same scan written as RGB, or as an indexed
image of two palette entries, stayed at eight bits (and RGB went to the
colour settings, as JPEG). Now these are packed to one bit first:
- eight-bit DeviceRGB whose every pixel is black or white becomes
DeviceGray; a decode array the same for each component becomes that
pair, another stops it. Calibrated RGB and RGB with a profile stay.
- an indexed image of 2, 4 or 8 bits that uses only palette entries 0
and 1 keeps its palette, whatever the two colours; a decode array
other than the default stops it.
Colour-key masks still stop all of them, and Retain leaves them to the
grey and colour settings. They are decoded through /DecodeParms given
by reference too (Document::with_direct_parms), and when downsampled a
tie goes to the dark sample of the image as packed: packed RGB is grey,
with grey's decode pair.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
A CCITT fax image that wasn't resampled was left as it was, so Group 3
images (the 1-D and 2-D codings fax software writes) stayed Group 3.
Group 4 codes each row against the one above and is usually much
smaller. Now only Group 4 alone skips decoding; Group 3 is stored again
as Group 4 when that is smaller as stored, and Retain still keeps it.
It reads an image's CCITT parameters (its /DecodeParms entry with Table
11's defaults) through pdfcraft_cos::Document::fax_params, from #4384.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
doc_reduce, the engine's reduced_bytes doc, the optimize README's
presets and the optimize.reduce parity note still said every image
above 225 ppi goes to 150 ppi; black-and-white images go to 300 ppi
above 450 ppi, as CCITT Group 4 when smaller.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Create PDF and the optimizer now store black-and-white scans as Group 4,
and redaction couldn't decode CCITT, so redacting one word on such a
scan removed the whole page image. A CCITT image (the last filter,
after any others) now decodes through Document::decoded_image and is
cleared in a Flate copy like any other image; one that can't be decoded
in full is still removed whole.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The README said an indexed image's palette decides which entry is the
dark one on a tie, but dark_is_one never reads the palette: entry 0
wins whatever its colour. The README, the function's comment and the
parity note now say so (from FredApps' review).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A 2 × 2 tie always gave sample 0, black in grey and the painted part of
an image mask with the default decode array. With an inverting one,
[1 0], 0 is white or unpainted, and in a separation 0 is no ink, so a
line half a new pixel wide could vanish. dark_is_one says which sample
is dark from the colour space and decode array: 0 in grey and of a
mask, 1 in a separation or a DeviceN of one colourant, each the other
way round when the decode array inverts; an indexed image keeps entry
0, as its palette, not the decode array, says which is darker.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
The PDF Optimizer and Reduce File Size downsampled colour and grey images
but not black-and-white ones. Settings::mono is now MonoSettings {
downsample, target_ppi, above_ppi, compression }, 300 ppi above 450 ppi
and CCITT Group 4 by default (Monochrome Images ▸ Downsample to;
doc_optimize mono: { downsample, ppi, above_ppi, compression }).
A 1-bit image or image mask (no filter, general-purpose filters, or CCITT
fax after any of them) and eight-bit grey of only black and white are averaged by
area: each new pixel takes the sample covering more of it, a tie 0, so a
dark line half a new pixel wide stays. They are stored as Group 4, or as
1-bit Flate when that is smaller; with Retain a resampled image keeps its
kind of compression. Images with a soft mask keep their size.
CCITT decoding moves from Export ▸ Images into pdfcraft-filters
(decode_ccitt, CcittParams, through hayro-ccitt), and
pdfcraft_cos::Document::decoded_image reads a fax image's /DecodeParms
for it (undoing filters before CCITT, such as ASCII85Decode, with any
/DecodeParms given by reference made direct first), so export
and the optimizer share one reader, and Group 4 scans can be
downsampled. A 600 ppi text page went from 79 KB to 40 KB.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
"Export ▸ Images reads byte-aligned Group 3 whichever way its fill
falls" read byte-aligned rows unaligned whenever /EndOfLine was set.
That broke byte-aligned Group 4 with /EndOfLine (refused); read Group 3
that says /EndOfLine but has no codes unaligned, and wrongly; and read
codes with the fill before them, but no /EndOfLine, on bytes: every row,
the wrong picture, nothing said. Now:
- Group 4, and rows not on bytes, read as the parameters say;
- Group 3 rows on bytes are read by the data: T.4 sends an end-of-line
code before the first row when it sends them at all, and no other code
starts with more than eight zeros. Data that starts with 11 zeros or
more (fill included) and a 1 has codes, and is read unaligned, where
the codes mark the rows whether the fill starts each code on a byte or
ends it on one; other data is read on bytes, whatever /EndOfLine says.
A reading that comes up short is reported rather than tried the other
way, where data cut short would read as other rows.
The Group 3 test exports nine pictures, stripes and eight of random
text-like runs (how a misreading comes out depends on the picture),
coded with T.4's terminating codes at /K 0 and 1: no codes, with
/EndOfLine and without; codes each starting on a byte or ending on one,
with /EndOfLine and without. Each exports as its picture, and each a
byte short is reported; at /K 1, codes with none before the first row
(not as T.4 sends them) export as their picture or are reported.
Byte-aligned Group 4 still reads with and without /EndOfLine. The
create.export-all-images parity note says what is still limited: such
codes may export wrong at /K 0, as the create README says. A rule tried
first, reading both ways and refusing an image that gave every row both
ways differently, failed on the stripes without codes (TIFF's Modified
Huffman layout): its unaligned reading gives every row too, wrongly. So
did one that read the other way when the first reading came up short: it
drew data cut short as other rows. cargo-mutants leaves no mutant of the
new lines alive.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
- A noisy 640 × 800 soft mask under 1200 × 1500 text: resampled to the
image's new size it shrinks only a little, by less than the grey
settings' JPEG adds over the packed image, so packing wins; not
counting the new mask passed every test before.
- The hex-text half of the bomb test also stores eight-bit
black-and-white, which must pack, as its comment says.
- The optimize README, the mono-compression parity note and both
progress logs say the soft mask counts.
- The Copy Image parity note no longer lists CCITT as missing: it
copies through Export's decoder, which reads CCITT now.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
Redaction doesn't decode CCITT yet, so a mark over part of a picture
Create PDF stored as Group 4 removes the whole picture (nothing leaks);
before this PR such pictures were eight-bit Flate and had only the
covered pixels cleared. The create README and the image-to-PDF parity
note say so; #4384 adds CCITT to redaction. The workspace's comment on
hayro-ccitt says Export uses it, not only tests.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
An eight-bit grey image of only black and white was packed to one bit
and stored, and the grey settings never saw it. For a dithered scan that
is bigger than what Reduce File Size made of it before, downsampled to
JPEG: 1-bit Flate can't shrink the dots (a 1200 × 1500 dither at 300 ppi
was 157 KB packed, 67 KB as before). Both are made now, and the smaller
as stored wins, counting a soft mask resampled with the image. Clean
text still packs to one bit. The packing also decodes no further than
its samples can need, as the other image steps do now.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
A fax image with /Filter [/ASCII85Decode /CCITTFaxDecode], say, was
skipped: only a lone CCITT filter went to the CCITT decoder. Now the
filters before it are undone first, and its parameters are the
/DecodeParms entry at its own place in the array (ISO 32000-2 §7.4.1),
not the first.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
Group 4 images (now written by Create PDF and the optimizer) would
otherwise stop exporting: they were reported as "can't be exported
yet". A CCITT fax image (its only filter) is decoded through
hayro-ccitt with its /DecodeParms (K, Columns, Rows, EndOfBlock,
EndOfLine, EncodedByteAlign, BlackIs1), masks included; /Columns has to
be the image's width, so a hostile value can't size the buffers.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
Copy Image and Copy Image in Original Format go through Export's
decoder, which reads JBIG2 now, so the view.copy-image parity note no
longer lists JBIG2 as missing. docs/target-app-parity.md's optimize row
lists JBIG2 symbol coding and lossy JBIG2 as missing instead of
monochrome JBIG2, with a status line and a revision row.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
Export ▸ Images skips an image whose JBIG2 page has another width or
more pixels than an export takes; a JBIG2 stencil mask refused the same
way is left out and the image exported opaque, as JPX and CCITT masks
are, which the export test now checks. The README and parity note said
only "is skipped". And redaction doesn't decode JBIG2 or Group 4 yet,
so a mark over part of an image the optimizer stored either way removes
the whole image; the optimizer README and parity note now say so (#4384
adds Group 4). Found in pre-push review.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
The optimizer README's and optimize.mono-compression's "not yet" lists
said rows wider than 32,767 samples aren't stored. That is Group 4's
limit (MAX_G4_COLUMNS); JBIG2 takes rows of up to 1,048,576
(MAX_JBIG2_COLUMNS). Found by CodeRabbit on #4805.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
JBIG2 images, and JBIG2 stencil masks, were reported as "can't be exported
yet", so an image the Optimizer stores as JBIG2 would stop exporting. They
are now decoded with hayro-jbig2 (already in the tree through hayro), with
their /JBIG2Globals from a DecodeParms dictionary or array, as JBIG2Decode
gives them: black as 0 (ISO 32000-2 §7.4.7). Unreadable globals, a JBIG2
page of another width, or fewer rows than the image skip the image; rows
past its height are dropped, so the output is bounded by the checked size.
docs/pdf-spec-parity.md §7.4 no longer says there is no JBIG2 encoding.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
pdfcraft_filters::encode_jbig2_generic writes 1-bit rows as a JBIG2
stream for JBIG2Decode (embedded organisation: a page information
segment and an immediate lossless generic region, no globals): template
0 with its nominal AT pixels, typical prediction, and the MQ arithmetic
coder (mq.rs), written from the JBIG committee's ISO/IEC 14492 Final
Committee Draft. The coder reproduces its Annex H.2 test sequence byte
for byte; output round-trips through hayro-jbig2, and Poppler renders
it the same as the original.
The optimizer's Monochrome Images gets JBIG2 (lossless) beside CCITT
Group 4 (still the default), doc_optimize mono jbig2; a document below
PDF 1.4 gets /Version /1.4 in its catalog. On 300 dpi text JBIG2 is
about a third smaller than Group 4.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
- Not only Export ▸ Images refuses a CCITT image until #4335: so does
everything that exports an image through it. Save Image As refuses
it, Copy Image fails, and Word, PowerPoint and HTML export leave the
picture out, with the page not reported. The optimize README and the
mono-compression parity note name them.
- optimize.mono-compression is partial now, so docs/target-app-parity.md
counts it on the table's own measurement: K Optimize and standards 15
shipped and 11 partial of 58 (35.3%), breadth 57.0% (423 + 75 of 808),
mainstream 63.3% (292 + 45 of 497), with a status line and a revision
row. ROADMAP.md's breadth rows and its K row say the same.
From reviews with the pdfcraft-review skill.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P6yUtvWGPsJpMLyh6pxSXG
