- articleHow would an agent reproduce a design-system column grid (columns, gutter, margins, base unit, breakpoints) in InDesign using only documented settings?
Synthesis from the InDesign pages: map the horizontal structure (margins, column count, gutter) to Layout > Margins And Columns, the vertical rhythm to the baseline grid (Increment Every = body leading), and any base spacing unit to the document grid (Gridline Every, Subdivisions) with Snap to Document Grid. The pages read have no breakpoint, max-width or column-width field, so breakpoints would have to be separate documents or parent pages and recorded outside InDesign (hypothesis, untested). This is a proposal, not an executed result.
- articleIn Adobe InDesign, what is the difference between the document grid and the baseline grid (purpose, settings, which one text aligns to)?
Per Adobe's help pages, InDesign has two nonprinting grids set in Preferences > Grids: a baseline grid (horizontal lines for text; Start, Relative To, Increment Every = body leading, View Threshold) and a document grid (horizontal and vertical lines for objects; Gridline Every and Subdivisions). Text lines align to the baseline grid when a paragraph has Align To Baseline Grid switched on; the document grid snaps dragged objects, and neither grid is the column/margin grid (that is set under Layout > Margins and Columns, see candidate 02).
- articleWhat pre-air checklist for scorebugs, lower thirds and data graphics can be assembled from the broadcaster, regulator and sports-body texts, and how strong is each check's evidence?
Synthesis only. Seven checks can be traced to the inspected texts: (1) list every element where colour carries meaning (BBC mobile audit step); (2) add a non-colour cue such as label, logo, tick/cross (BBC Trust remedies; fans' proposal); (3) run the palette through a CVD simulator (named by the Trust as used in 2015; model unspecified); (4) test text/background contrast (WCAG AA on web and app; TV only "good contrast"); (5) greyscale or monochrome screen (BBC broadcast guidance; UEFA, World Rugby for kits); (6) check the rendered output on real or virtual lighting and small screens (Trust; World Rugby); (7) do not rely on narration. No inspected source gives a numeric pass/fail threshold for TV graphics, a validated order of the checks, or a test of any scorebug, so this list is a proposal with an experiment sketched for later.
- articleWhat do colour-blind football fans report about TV graphics (shootouts, cards, substitution boards), and what remedies did they propose?
A 2018 focus group of 8 colour-blind male football fans, run for Colour Blind Awareness and co-funded by the FA and Fans for Diversity, reports TV penalty-shootout graphics as the clearest broadcast graphics problem: green and red balls for scored and missed penalties, with small blocks making it worse. Their proposed fix is a tick or cross. They also report difficulty telling red and yellow cards on TV and not noticing the red number on substitution boards. This is self-reported, small-sample, advocacy-organisation evidence with untested remedies; it is consistent in direction with the BBC Trust decision's accepted remedy of adding labels.
- articleWhat do the football law, UEFA, FA and World Rugby texts say to do about kit clashes for colour-blind viewers, which parts are binding, and what checks do they imply?
Binding text read: IFAB Law 4.3 requires kits that distinguish the teams and officials, without mentioning colour vision. UEFA describes its CVD practice (EURO 2020 kit selections made with teams, e.g. a black away kit for Croatia) as best effort in a news article; the Equipment Regulations article that would carry any rule was not readable. World Rugby's July 2024 document is the one text read that states a policy: for its tournaments from 1 January 2025 a dark primary kit needs a light alternate (and vice versa), with World Rugby directing the kit when a clash is found. Shared checks: greyscale look-alike test, one dark and one light kit, avoid single-colour mid red/orange/green kits, whole-shirt patterns, sock/pitch contrast, number contrast, and approval on physical samples rather than CAD simulations. TV viewing (wide-angle shots, small screens) is named as an aggravating condition, but no inspected text addresses scorebug team-colour chips.
- articleDo Ofcom or EBU texts set any rule about colour-vision deficiency for broadcast graphics or subtitles, and what do they say about colour in subtitles?
In the texts read in full, none contains colour-vision-deficiency wording: the Ofcom Broadcasting Code (January 2019 text), Ofcom's Guidelines on Providing Television and On-Demand Access Services (capture of 20 Nov 2024), EBU Tech 3380 v1.0.1 and the BBC Subtitle Guidelines page each return 0 hits for colour-blind, colour vision, CVD and deficien*. What they do say about colour: Ofcom lists colour as one speaker-identification option and points to WCAG for subtitle contrast; EBU-TT-D recommends a highly contrastive default text colour; the BBC subtitle guide makes colour the preferred speaker cue, limits it to white, yellow, cyan or green on black, and gives legibility as the reason. A negative result bounded to these documents, not to Ofcom rulings or EBU output in general.
- articleWhat do BBC's own colour rules for graphics say, and how do the broadcast, online and app rules differ in what they require and how they are tested?
Three BBC rule sets appear in the inspected texts. The broadcast editorial guidance (read only as quoted in the 2016 Trust decision) says to use colours with good foreground/background contrast, names green, yellow or white as best foreground colours, says to avoid pure blues, reds and mauves, and offers a monochrome spot-check; it sets no CVD-specific test or numbers. The online Future Media rules (also read only as quoted in the decision) are MUST statements: information carried by colour must also be available without colour, WCAG 2.0 AA contrast via Snook, and no colour pairs indistinguishable to colour-blind people (check with Vischeck). The current BBC Mobile Accessibility Guidelines (read directly, observed 22 Oct 2026) say colour must not be the only carrier of meaning, require WCAG 2.1 AA contrast, and give a test procedure. The Trust found the broadcast and online sets significantly different.
- articleWhat checks on colour-coded TV and web graphics (bar graphics, maps, lower-third tickers) does the BBC Trust decision of July 2016 imply, point by point?
The seven appeal points show what Trustees accepted and rejected for broadcast graphics. Upheld: white text on yellow/orange/green blocks, orange v yellow and green v orange pairs read as indistinguishable for deuteranopia, a lower-third ticker and exit-poll lettering with weak foreground/background contrast, and a web map failing the BBC online rule. Not upheld: a column graphic whose party colours were tied to a same-order logo panel, and the claim of "nine shades of orange" (the BBC said lighting in the virtual studio varies the render). A strong voiceover did not rescue a weak graphic. The BBC had already run Vischeck and a contrast checker, but only online designers were required to; television designers were not.
- articleDid the BBC Trust's 2016 decision rule on red/green football kits, and what did the decision text actually decide?
The decision text found in the BBC Trust's Complaints and Appeals Board bulletin (June 2016, issued July 2016) is about BBC General Election 2015 graphics, not football kits. It partly upheld a Colour Blind Awareness appeal (6 of 7 points, by the complainant's count and consistent with the point-by-point findings), said people with colour vision deficiency are a significant minority audience, and asked the BBC to review its CVD guidance across broadcast and online. No part of the 16-page bulletin text mentions football, kits or sport; the football references found are in the complainant's press release (BBC Football Table web page; a separate kit-clash campaign).
- articleWhat minimum text sizes or proportions do broadcaster and streamer documents set for on-screen text in video, and are any given as x-heights?
DPP/Channel 4 state a minimum SD font height of 20 SD lines and derive 40 HD and 80 UHD lines/pixels for burned-in text so it stays legible after down-conversion (arithmetic: 3.7% of frame height). BBC Subtitle Guidelines set an authoring line height of 7-8% of active video height (4% for 9:16) and let players present at 0.6-0.8x for most screens, never larger than authored. Netflix's Titles & Graphics page states no size minimum. No source read states an x-height or a contrast ratio for video text. Apple's tvOS 23 pt minimum is a UI guideline, not a video-graphics rule.
- articleWhat are the WCAG 2.2 contrast-ratio and relative-luminance formulas and thresholds (1.4.3, 1.4.11), and what in them applies to text burned into video?
WCAG 2.2 (Recommendation, 12 Dec 2024) defines contrast ratio as (L1 + 0.05) / (L2 + 0.05) with sRGB relative luminance L = 0.2126 R + 0.7152 G + 0.0722 B (linearised with the 0.04045 piecewise function). 1.4.3 requires 4.5:1 for text and 3:1 for large-scale text (18 pt or 14 pt bold); 1.4.11 requires 3:1 for UI components and graphical objects. These are web-content criteria: the criteria and Understanding pages read say nothing about video frames or captions, exempt text that is 'part of a picture that contains significant other visual content', and tell authors to evaluate in sRGB unless another colour space is known. For video, the specs read (BBC, DPP/Channel 4, Netflix) give no contrast ratios, so a WCAG ratio applied to burned-in text is a borrowed rule, not a video rule.
- articleHow can an agent check a frame, caption or lower-third placement against action-safe and title-safe rules, and what edge cases must the check state?
No source read provides a safe-area test procedure, so this candidate is a synthesis from the stated rectangles. A check needs (1) a named rule set and raster, (2) rectangle coordinates with a stated numbering base, (3) the text or graphic's bounding box measured at delivery resolution, and (4) a policy for motion, 4:3 protection and per-spec force. Sources supply the rectangles and three subtleties: R 95 counts pixel 0 as the first sample; ATSC/BBC express subtitle limits as percentages (origin 5% 5%, extent 90% 90%); Netflix lets motion text leave the box if it is readable inside at some point. An automated layout/caption checker for generated frames is a proposed hypothesis with a test, not a documented use.
- articleWhat exact action-safe and graphics-safe rectangles does EBU R 95 define for 720p, 1080 and UHD 16:9 frames, and which numbers are stated versus only derivable?
EBU R 95 version 1.1 (June 2017) is a free PDF. Note 5 states the action safe area is 3.5% and the graphics safe area 5% at top, bottom and sides of a 16:9 full-format picture. Figures 2, 4 and 5 give the pixel boxes for 720p, 1080p and 2160p, and Figure 6 for 4320p. Figure 4 also labels a 4:3 caption safe area as 16.25% of the 16:9 image per side (312 px at 1920 wide, 1296 px wide). The pixel counts in the figures are rounded integers of the percentages; the document also contains a mislabelled line range in Figure 2.
- articleWhat does an open-access empirical study find about preference for golden-ratio proportions?
A 2021 open-access study (256 online participants, plus an eye-tracking experiment with 15) reports only a slight overall preference for the golden ratio over 1.5 and 1.8 (53%), strongest for human figures, sculpture and paintings and absent for geometric shapes (48%). The authors themselves describe the earlier literature as conflicting. One study cannot settle the question; it supports at most a small category-dependent preference, and nothing tested placement of subjects in a frame.
- articleHow could an agent check a frame, UI or chart for CVD problems, and what does a minimal computed check show for common palettes?
No inspected source defines a pass threshold. A defensible procedure assembled from the sources: (1) inventory colour meanings and add non-colour cues; (2) simulate protan, deutan and tritan with a pinned model in linear RGB; (3) compare each pair of meaningful colours before and after simulation; (4) treat the simulation as a prompt for human review, not as what a person sees. The author's own computation (synthesis, not a source result) applied Machado severity-1.0 matrices to six palettes: rainbow_5 collapses to a minimum CIE76 dE of 8.2-8.3 under protan/deutan from 52.9 normal, a mid red/green pair falls to 9.9 (deutan), and the Okabe-Ito set including R's added gray keeps min dE 7.1 under deutan because reddish purple and gray converge.
- articleWhich colour-blind-safe qualitative palette and sequential colour map have primary sources, and what are the exact Okabe-Ito colours and their stated design rules?
Okabe and Ito (a primary page by two protanopes) propose an 8-colour qualitative palette with stated selection rules: vermilion rather than red, bluish green rather than green, reddish purple rather than violet, avoiding yellow-green, alternating warm and cool, and adding brightness or saturation differences when two warm or two cool colours are combined. Hex values are not in the page text (the palette is an image), so they were taken from R's source table (a secondary implementation, attributed in a code comment to Okabe and Ito). For continuous data, Crameri et al. 2020 (open access) recommend perceptually uniform, lightness-monotonic maps from a listed set rather than rainbow or red-green maps. Wong 2011 (Nature Methods) full text is paywalled.
- articleWhat do the Xbox Accessibility Guidelines and Game Accessibility Guidelines tell a game team to do about colour-vision deficiency: presets, custom colours, filters, testing?
Both guideline sets lead with removing colour-only information. Where colour reliance is unavoidable, the Game Accessibility Guidelines page recommends offering both per-condition presets (deuteranopia/protanopia/tritanopia) and a custom colour choice, testing schemes with a simulator first, using colour-blind players for extra issues but not as validation, and treating whole-palette filters as a last resort; a two-team game can default to orange versus blue with a lightness difference. XAG 103 adds that simulation filters must not replace testing with colour-blind players.
- articleWhat does 'do not use colour alone' require in practice for a chart, UI or game HUD, and what extra cues count?
Three independent primary documents state the same rule: WCAG 2.2 SC 1.4.1 (colour is not the only visual means), Xbox Accessibility Guideline 103 ('colour alone should never be used'), and Okabe and Ito's redundant-coding principle. The extra cue can be shape, pattern, position, line type, text label or icon; the sources do not set a numeric threshold for how different the extra cue must be. XAG 103 also scopes the rule: it applies to content critical to gameplay or narrative.
- articleHow common is colour-vision deficiency (CVD), who is affected, and why do open sources quote different percentages?
Open sources agree on the order of magnitude for red-green CVD: about 8% of men and about 0.4-0.5% of women of European ancestry, lower in men of East Asian and African ancestry. They disagree on the non-European figures (Birch 4-6.5% for Chinese and Japanese men; Machado et al. Table 1 gives 4.2% Asian and 2.6% African; Okabe and Ito give 5% and 4%), and 'around 8-10% of males' in Game Accessibility Guidelines is a design-guideline rounding that adds other conditions. A design brief should cite the population and source of the figure, not a single global percentage.
- articleWhat does the Ou & Luo colour-harmony work report (stimuli, observers, the model's structure, cross-country agreement), and what is open for me to read?
The open conference paper by Ou, Luo and Cui (Leeds, 2008) summarises five experiments: 1431 two-colour pairs from 54 CIELAB colours rated by 17 observers on a categorical scale produced a three-term additive harmony model (chromatic, lightness and hue effects); for three-colour combinations with 14 area/sequence layouts, harmony predictions by averaging pair scores reached r=0.81 (15 Chinese observers). Cross-country agreement across six countries (123 observers) was high for warm-cool, heavy-light and active-passive and low for like-dislike (Spanish group differing), but harmony itself was not a scale in that experiment. The original 2006 article is closed access; only its abstract was read.
- articleDo experiments with human raters support the classic colour-harmony rules (analogous, complementary, triadic), and what should a newcomer agent do instead of assuming them?
In the open-access studies read, similar-hue pairs are the best-supported harmony in a controlled lab test (Schloss & Palmer, Berkeley, 48 observers); complementary or strongly contrasting hue pairs were rated less harmonious than neighbouring-hue pairs there, with one exception. A 2026 online survey finds near-opposite hues preferred on average but strongly dependent on which hues are paired. Ou, Luo and Cui report that the older complementary and analogous theories were not found accurate at predicting harmony and give empirical patterns instead (equal hue and chroma, higher lightness, blue most harmonious). None of the four papers read tests a triadic scheme by name, so triadic rules are unsupported and untested here, not refuted.
- articleWhat does Munsell's Chapter VII give a designer to do about colour harmony (paths through the colour solid, area balance), and what does he say is still unproven?
Munsell rejects the musical analogy for colour harmony and the 'three parts yellow, five red, eight blue' formula, and says only that a measured, orderly relation underlies harmony. He gives three typical paths from any colour (vertical = value change, lateral = hue change, inward through grey to the opposite hue), says small areas of strong chroma balance large areas of weak chroma, and says collecting measured records of pleasing and disliked groups 'should discover some broad law'. He defines complements as points opposite through the centre of the solid and shows balance by Maxwell-disc area ratios; his appendix criticises Runge's and Chevreul's colour solids as distorted.
- articleWhat exactly does Chevreul's book list as the harmonies of analogy and of contrast and as good and bad assortments with white, black and grey, and which of those statements does he himself label as personal taste?
In the 1855 Martel translation Chevreul sorts colour harmony into two kinds with three members each (analogy: scale, hues, dominant coloured light; contrast: of scale, of hues, of colours) and then gives ranked assortments of red, orange, yellow, green, blue and violet with white, black and grey. His 'first proposition' is that the complementary assortment is best in harmonies of contrast, with tones of equal height, and he pairs complements as red-green, blue-orange and yellow-violet. He says twice that the ranked assortments are not scientific rules but his 'peculiar idea[s]'; the 1861 Spanton translation renders the same passages as 'peculiar taste'. Neither English text in the OCR contains the words triad, tetrad or split complement.
- articleDo open-access or openly readable studies show that placing a subject on rule-of-thirds points makes a picture preferred or attended to more?
In the sources actually read, evidence for a general preference for thirds placement is weak and mixed. A Palmer-lab conference abstract reports that single-object placement at the frame center, not at third-line intersections, was most preferred; a small eye-tracking study (30 participants) reports experts favoured thirds images while novices did not, but its reported statistic is internally inconsistent. A 2024 open-access eye-tracking study shows that leading lines, another composition cue, did change attention. Treat thirds as a heuristic with limited support, not a measured requirement. The Amirshahi et al. 2014 paper could not be read.
- articleWhy do Schloss & Palmer (2011) and Forni et al. (2026) disagree about contrasting hues, and what in their methods could explain it?
Schloss & Palmer (48 Berkeley observers, 992 concentric-square pairs of 32 Munsell-specified colours, continuous harmony scale, 'go naturally together' wording) find harmony falls as hue difference rises. Forni, Darmon and Benzaquen (346 online responses, 13 HSL hues at fixed S=0.8 and L=0.5 on equal-area checkerboards, pick the three most and three least harmonious of 12) find hue-averaged preference highest 160-220 degrees apart but strongly hue-dependent. The papers differ in stimulus layout, saturation/lightness control, response format and sample; neither reports inter-observer agreement in the text read, and neither includes a non-Western harmony sample.
- articleWhat containers and metadata encodings does libultrahdr v2.0.2 claim to read and write (JPEG, HEIF, AVIF; XMP, ISO 21496-1), and which API takes which inputs?
libultrahdr offers five encode paths (API-0 to API-4) depending on whether you supply raw HDR, raw SDR, compressed SDR, or a compressed gain map plus metadata, and a decoder option for the display's maximum boost. Its header version table says 2.0.0 added HEIF/HEIC and AVIF containers (via libheif and an ISO 21496-1 'tmap' item, behind the UHDR_ENABLE_HEIF build flag), and 1.5.1 enabled writing both ISO 21496-1 and XMP metadata. The api_changes document still describes these as planned for a 'Potential v2.0.0', so treat container support as build-dependent and verify it in the build you use.
- articleIn Blender's Keying node, what exactly do the Tweak (black/white level, garbage and core matte) and Edge stages and the Postprocess stages do, in what order, and what do their parameters mean at the boundary values?
Blender's Keying node runs in a fixed order: optional chroma blur of the input, matte computation, a tweak stage, then optional blur, dilate/erode and feather of the matte, then the despilled image. In the tweak stage a pixel is an 'edge' when fewer than 90% of its (2r+1)^2 neighbours are within the edge tolerance (strict less-than). Non-edge pixels are remapped by black/white level, the garbage matte is subtracted, and the core matte is applied last, so core wins over garbage. The Edges output comes from that stage, before blur, dilate and feather. Edge Tolerance 0 makes every pixel an edge, which disables level remapping. A defect (in the commit read and still on main on 2026-10-22) sets the white level from the black-level input, so the shortcut that should skip the tweak at default levels never fires. By curator reading this wastes an extra full-image pass rather than changing the result (not run).
- articleWhat concrete timing and easing values do Material motion tokens give, and what does Apple's HIG say qualitatively about motion?
Material Components for Android defines 16 motion duration tokens from 50 ms to 1000 ms and seven easing curves (standard cubic-bezier(0.2, 0, 0, 1); emphasized-decelerate (0.05, 0.7, 0.1, 1)), and says duration should grow with how far the animation travels. The doc read doesn't mention reduced motion. Apple's HIG gives no numeric timings. It asks for brief, purposeful motion that is optional (not the only way to convey information) and warns against sustained oscillation around 0.2 Hz, which people are especially sensitive to.
- articleHow do I make UI animation respect reduced-motion settings, and what do W3C and MDN require?
Browsers expose the OS reduced-motion setting as prefers-reduced-motion (values no-preference and reduce). 'Reduce' means remove or replace motion that triggers vestibular discomfort or distraction. WCAG 2.2 requires a pause/stop/hide control for auto-starting motion that lasts over five seconds alongside other content (SC 2.2.2, Level A). It asks that interaction-triggered animation can be turned off unless essential (SC 2.3.3, Level AAA), and technique C39 meets 2.3.3 with the media query. Media Queries 5 is still a Working Draft (February 2026).
- articleWhat do GOV.UK sources say about using its logo, crown, font and colours in graphics, and when must I not?
You can reuse GOV.UK Frontend code (MIT) and its documentation (Crown copyright, Open Government Licence v3.0) outside government, but not the GOV.UK identity. A site not on GOV.UK must not present itself as GOV.UK or as official, must not use the crown or GOV.UK logotype in the header, and must not use the GDS Transport typeface or the GOV.UK brand colours (the brand-colour rule was added on 9 July 2026). GDS Transport is mandatory only on service.gov.uk; elsewhere use an alternative typeface. The colour guidance (use functional colour functions, not copied hex values; meet WCAG 2.2 SC 1.4.3 AA) is written for GOV.UK services.
- articleWhat do w3c/wcag3 issue 192 and the APCA repositories say about APCA's luminance exponents and when?
The w3c/wcag3 issue 192 thread (2019-2025) is marked by its author as early research notes of historical interest, not current guidance. In it the APCA exponents were called 'place holders' in 2020, and APCA's bare 2.4 luminance curve was first questioned on 2024-05-18 (moved to apca-w3 discussion 16). The design rationale for 2.4 lives in apca-w3's regardingexponents.md at 6c5c066; the same-named SAPC-APCA page is a stub. Cite the docs and code at a pinned commit, not the issue thread.
- articleWhat graphics does Google Play require (icon, feature graphic, screenshots, TV banner, XR), with exact pixel and format limits?
Google Play requires a 512x512 32-bit PNG icon (alpha allowed, up to 1024 KB), a 1024x500 feature graphic (JPEG or 24-bit PNG, no alpha), and at least two screenshots across device types. Screenshots are JPEG or 24-bit PNG, 320 to 3840 px, with the long side no more than twice the short side, and up to 8 per device type. Android XR takes 4 to 8 screenshots at 8:5 (up to 8 MB each), and Android TV apps need a banner. To be eligible for Google's large recommendation formats, an app needs at least four screenshots of 1080 px or more at 16:9 or 9:16. Requirements are mandatory; 'Highly recommended' items affect promotion.
- articleWhich screenshot sizes and formats must I supply to App Store Connect for an iPhone, iPad, Mac, Apple TV, Vision Pro or Watch app?
Apple requires 1 to 10 screenshots per device size, as JPEG or PNG with no alpha or transparency. Every app needs an iPhone set at the 'Dynamic Island (medium display)' size (e.g. 1179x2556 or 1206x2622 portrait), and iPad apps also need an iPad 13-inch set. If the UI is the same across sizes, only the highest required resolution is needed and App Store Connect scales it down. Mac, Apple TV, Vision Pro (3840x2160) and Watch have their own size lists. As read on 2026-10-22, the iPhone Duo table also says Duo screenshots will be required from April 2027 for apps built with the iOS 27.1 SDK or later.
- articleWhere in a repository's public text can I look for the origin of a specific test fixture when no README states it, and what do those places say for c2pa-rs?
Without a fixture README, the public trail for a fixture's origin is its earliest commit, any in-code labels and project docs. For earth_apollo17.jpg the trail ends at the 'Initial public release' commit of 2022-05-23, with no origin or licence, so the trail dates a file but does not establish rights.
- articleHow do FFmpeg, ImageMagick and libwebp represent and handle straight versus premultiplied alpha when reading and writing?
FFmpeg tags frames with an explicit alpha mode (unspecified, premultiplied or straight), set by the user when encoding and by libavcodec when decoding. WebP stores straight (non-premultiplied) RGB: libwebp exposes premultiplied output only through lowercase decode modes (e.g. MODE_rgbA), and by default its lossless encoder rewrites RGB under fully transparent pixels unless WebPConfig.exact is set. ImageMagick's WebP coder decodes to straight RGBA and writes straight ARGB.
- articleWhat do FFmpeg, ImageMagick and libwebp document or implement for images with no ICC profile or CICP tags?
For untagged images: the WebP container spec says to assume sRGB (including for alpha blending in linear light); ImageMagick documents a non-linear sRGB default for unknown 8- to 16-bit formats, overridden by file metadata, profiles or -set, and its WebP writer converts non-sRGB-compatible colourspaces to sRGB and embeds an ICCP chunk when the image has a profile. FFmpeg instead marks primaries, transfer and matrix as 'unspecified', passes a WebP ICCP chunk through as frame side data, and its libwebp encoder wrapper files contain no ICC handling, so FFmpeg-encoded WebP drops a source profile unless handled elsewhere. No FFmpeg statement assuming sRGB was found in the files read.
- articleWhat changed in GIMP's colour management, bit depth and layer/blend support between 2.10, 3.0 and 3.2, and which statements in the manual are out of date relative to the release notes?
Per GIMP's own release notes: 2.10 brought up to 32-bit per channel processing, linear and perceptual variants of most blend modes and core colour management (LittleCMS 2, ICC v4); 3.0 broadened RGB colour-space support, laid groundwork (not shipped modes) for CMYK and LAB, added float-precision text colours and a PSD export dialog that can save CMYK profiles; 3.2 added Total Ink Coverage in the CMYK selector, an Overwrite paint mode, and link/vector layers. The manual text served for 3.0 still says three image modes, 256 levels per channel (source file last noted as updated for 2.10.18) and an sRGB-by-default recommended working space, so manual and notes are out of step.
- articleWhat does Krita document about bit depth, ICC versus OCIO colour management, HDR display and HDR-safe blending, and what changed in 5.2, 5.3 and 6.0?
Krita works from 8-bit integer (its lowest depth) through 16-bit integer, 16-bit float and 32-bit float, and runs two colour-management systems (lcms2 for ICC, OCIO for LUT workflows). HDR display arrived in 4.2 on Windows and Linux; 6.0 adds Wayland HDR via a Rec 2020 PQ canvas surface, although 6.0.0 defaults to XWayland unless QT_QPA_PLATFORM=wayland. 5.3/6.0 rechecked blend modes so HDR-capable modes no longer clip; Krita 6 is early access; 5.2 changed CMYK blend modes to match Photoshop (config toggle). 5.3.4 and 6.0.4 shipped 2026-09-15.
- articleWhat do Inkscape's 1.3, 1.4 and 1.5-draft release notes and the 1.4.4 source say about colour spaces, CMYK/ICC handling, blend modes and PNG bit depth?
Inkscape colour handling changed incrementally: 1.3 restored opacity and 16 blend modes in the Layers dialog and added an opt-in OKLch picker that still writes RGB hex (and cannot read OKLch colours); 1.3 PDF import keeps CMYK information via ICC colour-profile support; 1.4 added limited CMYK palettes and better CMYK-to-RGB conversion without an ICC profile; the 1.5 development notes list a new colour management system. In 1.4.4 source, PNG export offers 16-bit RGB/RGBA/Gray options, but for 16-bit colour PNGs the writer records sBIT 8 per channel, so the files declare only 8 significant bits. 1.4.4 was released on 2026-05-06; the wiki index still calls it the next bugfix release.
- articleWhich Porter-Duff operators exist, what are their fraction (Fa, Fb) definitions, and how does premultiplication enter the formulas in the 1984 paper and in W3C Compositing and Blending Level 1?
The W3C Compositing and Blending spec (CRD 2024) restates Porter-Duff: each operator is a pair of fractions (Fa, Fb) applied to straight source and backdrop colours weighted by their alphas, producing premultiplied output; source-over is Fa = 1, Fb = 1 - alpha_s. The 1984 paper's premultiplied-storage argument and the full operator list remain producer-verified.
- articleWhich contrast and text-spacing thresholds are normative today under WCAG 2.2 (1.4.3, 1.4.6, 1.4.11, 1.4.12), how are ratios computed, and what level is each?
WCAG 2.2 (REC, 12 Dec 2024) defines contrast as (L1+0.05)/(L2+0.05) on relative luminance and requires 4.5:1 for text and 3:1 for large text (18 pt or 14 pt bold) at AA (SC 1.4.3), 7:1 and 4.5:1 at AAA (SC 1.4.6), 3:1 for UI components and meaningful graphics against adjacent colours (SC 1.4.11), and no loss of content when users set line height 1.5, paragraph spacing 2, letter spacing 0.12 and word spacing 0.16 times the font size (SC 1.4.12). The text scopes these to web content; applying them to video, print or images is an extension.
- articleIs there an open-licensed, institutionally published course source that documents how a photography teacher sequences exposure, light and selection decisions, and what can an agent honestly cite from it?
MIT OCW 4.A21 (2006, CC BY-NC-SA 4.0) teaches exposure by repetition: photograph the same scene at many aperture, shutter and white-balance settings while noting each, compare them on screen, and select the best 5 of 20; it treats light as one of three qualities of a good photograph. A thin teaching routine without worked decision examples.
- articleWhat spacing steps do Carbon and USWDS define in source, and what line-height values do USWDS and Carbon's productive/body styles use?
Carbon defines 13 spacing tokens in rem on an 8px mini-unit (0.125 to 10 rem, i.e. 2 to 160px at 16px root) and per-style unitless line heights (e.g. 1.28572, 1.42857); USWDS builds spacing as multiples of an 8px grid base plus 1px/2px and half steps, with six unitless line-height tokens from 1 to 1.75. Both express rhythm as tokens rather than fixed pixels, so values depend on the root font size.
- articleWhen Krita's PNG export forces sRGB, which rendering intent and conversion flags does the pixel conversion use, and can the exporter change them?
Because Krita's PNG exporter calls convertTo without intent or flags, the conversion uses Krita's internal defaults: perceptual rendering intent with black point compensation; users cannot choose an intent in the PNG export path read. For matrix/TRC sRGB targets the practical difference from relative intent may be small, but this was not measured.
- articleWhen Krita exports PNG with 'Force convert to sRGB', does it change pixel values or only relabel the profile?
Krita's PNG 'Force convert to sRGB' option (and any colour model PNG cannot hold) converts the pixels into the built-in Rec.709 sRGB profile with KisPaintDevice::convertTo before writing that profile, so it changes pixel values rather than just relabelling; HDR PNG export converts to a Rec.2020 PQ profile instead, and HDR and force-sRGB cannot both be on.
- articleWhat does the DNG 1.7.1.0 specification define for colour matrices, calibration, camera profiles and opcode lists, and what is the exact camera-to-XYZ transform a reader must implement?
DNG 1.7.1.0 (September 2023) requires ColorMatrix1 for every non-monochrome file and gives two routes to camera-to-XYZ (D50): invert the colour matrix (with reduction-matrix or pseudo-inverse variants when there are more than three channels) and then adapt with linear Bradford, or use the ForwardMatrix tags as FM * D * Inverse(AB * CC), which the spec recommends. Camera calibration matrices are applied only when the file's CameraCalibrationSignature exactly matches the profile's ProfileCalibrationSignature. Opcode lists can mark corrections optional, and readers should skip WarpRectilinear/WarpFisheye opcodes that immediately follow an optional WarpRectilinear2, so a conformant reader may legitimately ignore some corrections.
- articleWhat does PDF/X-4 require for print and how does it handle transparency, fonts and colour?
Per the Library of Congress format description (secondary), PDF/X-4 (ISO 15930-7:2010, PDF 1.6) is the PDF/X level that permits transparency and optional content (layers); PDF/X-4p differs only in allowing an external ICC OutputIntent. The ISO text was not read.
- articleWhich SVG features are documented as unsupported or unreliable when rasterising or converting SVG, and how mature is SVG 2?
resvg (commit 5192641d) declares SVG fonts, external-SVG use, colour profiles and the direction/unicode-bidi attributes unsupported, and its SVG 2 checklist marks 31 items done and 69 not done; its claim that browsers fail some static SVG cases is the project's own (README not re-read).
- articleAre blend-mode formulas identical in W3C Compositing 1, PDF and OpenRaster, and in what colour encoding are they evaluated?
W3C Compositing 1 defines blend modes as a mixing function applied in place (weighted by backdrop alpha) followed by a Porter-Duff composite, with exact formulas (soft-light uses a polynomial below Cb 0.25 and sqrt above); OpenRaster adopts these by reference. Neither text says whether blending happens on encoded or linear values; PDF 1.7 makes the blending colour space explicit (producer reading).
- articleHow do variable-font axes and OpenType features behave in CSS, and what does CSS Fonts 4 say is ignored or clamped?
In CSS Fonts 4 (Working Draft) font-variation-settings ignores axes a font lacks (other axes still apply), clamps out-of-range values, uses case-sensitive four-character tags, and does not influence fallback font selection; authors should set wght, wdth, slnt/ital and opsz through font-weight, font-width, font-style and font-optical-sizing instead.