A field guide
to colour accuracy.

What is ChromIQ?

A friendly front-end for a serious piece of colour science — so you can stop memorising CLI flags and start printing things that look the way they should.

Every printer lies a little. Send the same RGB triple to two different machines and you'll get two noticeably different greens, two different skin tones, two different blacks. An ICC profile is the translation table that teaches your Mac how your specific printer, on this specific paper, with this specific ink, actually reproduces colour — so Lightroom, Photoshop, and ColorSync can compensate before the print leaves the nozzle.

Building that translation table by hand is tedious. You generate a random test chart, print it, measure every single patch with a spectrophotometer, then feed the results back through half a dozen command-line tools. Miss a flag and you have to start over. ChromIQ is the macOS app that does the tedious parts for you while leaving every knob accessible when you need it.

What's inside the box

• Five tabs, one workflow. Create chart → print → measure → build → check & refine. Each tab knows what the previous one produced, so files load themselves.
• Guided & Manual modes. Pick an instrument and a paper size and get a sensible chart in two clicks — or open Manual and tune every targen, printtarg, and colprof flag with tooltips that explain what each one actually does.
• Live previews. The generated chart TIFF renders inline, zoomable, page-by-page, before you waste a sheet of paper.
• Honest feedback. After building a profile, profcheck tells you the average and peak ΔE and points out exactly which strips to re-measure.

What it isn't

ChromIQ is a GUI, not a colour engine. All of the actual heavy lifting — random target generation, spectral measurement, profile construction — is done by ArgyllCMS by Graeme Gill, which you install separately. ChromIQ's job is to keep you out of Terminal and stop you losing track of which .ti2 goes with which .ti3.

Installation
& setup.

Two downloads, one preferences check, and you're ready to generate a chart.

System requirements

Step 1 — Install ArgyllCMS

ChromIQ calls out to four ArgyllCMS binaries: targen, printtarg, chartread, and colprof. Download ArgyllCMS 3.5.0 from argyllcms.com/downloaddev.html, unpack the archive, and move the Argyll_V3.5.0 folder into /Applications/. The default location ChromIQ looks for is:

# ChromIQ looks here first — you can change the path in Preferences.
/Applications/Argyll/bin/
  targen
  printtarg
  chartread
  colprof
  profcheck
  …and the rest of the Argyll toolset

Step 2 — Install ChromIQ

Open the latest GitHub release and grab one of:

macOS

Open the DMG, drag ChromIQ to Applications, eject the image. Because the app is ad-hoc signed rather than notarized, macOS will refuse the first launch if you double-click. Right-click the app in Applications → Open → Open to clear Gatekeeper once — every launch after that is a normal double-click.

Windows beta

Extract the ZIP, open the ChromIQ folder, and run ChromIQ.exe. Windows SmartScreen may warn on first launch — click More info → Run anyway. ArgyllCMS is auto-detected in C:\Program Files\ArgyllCMS\bin and %LOCALAPPDATA%\ArgyllCMS\bin; download it from argyllcms.com (win64).

Step 3 — Verify the Argyll link

On first launch ChromIQ auto-detects the Argyll binaries. If it can't find them, a setup banner appears at the top of the window with a direct download link. Either way, open ChromIQ ▸ Preferences ⌘, and confirm the path:

1. Point ArgyllCMS bin path at the folder containing the binaries (default /Applications/Argyll/bin).
2. Click Test binaries. You want four green checkmarks: targen, printtarg, chartread, colprof.
3. Set your Preferred instrument and Preferred paper size — these become the defaults on the Create Chart tab.
4. Pick an Output folder. The default ~/ChromIQ/ is fine; each session creates its own subfolder inside it.

Running from source optional

If you want to hack on ChromIQ or run it without a DMG:

git clone https://github.com/itsab1989/ChromIQ.git
cd ChromIQ
python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt
python main.py

Python 3.12+ and PyQt6 ≥ 6.11 are required. Full build instructions live in HOW_TO_BUILD.txt at the repo root.

Getting started,
end to end.

Your first profile in five steps. Set aside about an hour of active time, plus a drying gap between printing and measuring.

1. Create the test chart Tab 1

   Open the 1. Create Chart tab. Leave the mode on Guided for your first run. Give the target a name, pick the Instrument you own, the Paper size you'll print on, and the Number of pages — usually 1 or 2.

   ChromIQ looks up the maximum patch count that will fit and shows it in big cyan type under Calculated Patches. Click Generate Chart. The TIFF preview appears on the right once targen and printtarg finish.

   

   Fig. 1.0Create Chart · Guided mode · ColorMunki / i1Studio · A4 · 3 pages · 630 patchesTIFF preview

   Tip Leave Suppress left clip border (-L) on unless you're using a physical paper-clip jig for your instrument. Turning it off buys ≈15 mm of extra printable width — worth ~15% more patches — but only if your setup can handle the edge.

2. Print the chart Tab 2

   Switch to 2. Print Chart. Pick your printer from the dropdown (click the ↺ next to it if it's missing). Set paper slot, media type, and print quality to exactly the settings you plan to use with this profile in production.

   Click Print Current Page, or Print All Pages if you're doing a multi-page chart. On macOS, ChromIQ sends the chart via a PostScript Level 2/3 pipeline with colour management disabled automatically — no driver settings need changing. On Windows, the native print dialog opens; disable ICM in the driver before printing.

   

   Fig. 1.1Print Chart · Epson ET-8550 · page 1 of 3PostScript → CUPS

   Dry time Allow the print to dry at least 1 hour before measuring — 24 hours for best accuracy on pigment inks. Pigment shifts slightly as it settles; measuring wet prints is one of the most common causes of a bad profile.

3. Measure the chart Tab 3

   Connect your spectrophotometer, then open 3. Measure. The .ti2 file from Step 1 is already loaded — you should see its path next to Target File. Click Start Measurement.

   A dialog walks you through calibration. When it closes, put the instrument at the top-left of strip A and follow the on-screen navigation:

   • f — advance to the next strip
   • b — go back to the previous strip
   • n — jump to the next unread strip
   • d — finish & save when all strips are done
   • Esc / q — quit without saving

   

   Fig. 1.2Measure · Guided mode · Calibration Complete dialog · strip A armedPage 1 of 3

4. Build the profile Tab 4

   On 4. Build Profile the .ti3 measurement file from Step 3 is already loaded. For a first pass the defaults are fine: Lab cLUT algorithm, Medium quality, Perceptual + Saturation gamut mapping with sRGB as the reference source.

   Click Build Profile. A progress bar appears while colprof runs (20 seconds to a few minutes depending on quality). When it finishes, a dialog offers three next steps:

   

   Fig. 1.3Build Profile · Guided mode · colprof running · Media Surface + Color Type controlsWorking hard…

   • Install on this Mac — registers the .icm in ColorSync so Photoshop, Lightroom, and Preview can see it immediately.
   • Check Profile Quality → — jump straight to Step 5.
   • Done — dismiss the dialog and move on manually.

5. Check & refine Tab 5

   The final tab runs profcheck against your measurements and grades the profile with average and peak ΔE numbers. If you're below ΔE 1.5 avg and ΔE 3.0 peak, ship it. If not, ChromIQ flags the worst strips and offers a guided re-measurement.

   

   Fig. 1.4Check & Refine · Guided mode · ready to analyse · ΔE threshold 2.0printer test.icc loaded

   Click Guide Me Through Refinement. ChromIQ navigates to each flagged strip one at a time, you re-measure only those, then return to Step 4 and rebuild. Repeat until you're happy — usually one or two passes.

   Shipping A good photo-printing profile is typically ΔE_avg ≤ 1.5 with ΔE_max ≤ 3.0. For proofing or critical press work you'll want ΔE_avg ≤ 1.0 and ΔE_max ≤ 2.0 — achievable, but expect 2–3 refinement passes.

And that's it — you now have a custom ICC profile for your exact printer / paper / ink combination, installed on your Mac, ready to select as the destination profile in your editor of choice.

Feature
reference.

What each tab does, what every checkbox means, and where the app hides the details.

4.1 · Create Chart

The Create Chart tab has two modes that share the same preview pane.

Guided mode

Pick an Instrument, a Paper size, and a Number of pages. ChromIQ consults its empirical patch-capacity database (stored in data/patch_db.py, measured with Argyll 3.5.0 at 300 DPI) and shows the optimal patch count instantly. The combination of fixed values it applies is printed in green below the inputs, for full transparency:

Guided mode applies these fixed settings:
targen -d2 -G -e6 -B6 -g14
printtarg -iCM -pA4 -t300 -L -h chart

Manual mode

Every targen and printtarg flag is exposed as a labelled widget with a tooltip popover that explains what it does in plain English. The form is auto-generated from data/parameters.yaml, so whatever version of the app you're running matches its own Argyll binding exactly. Expert-only parameters are collapsed behind a disclosure.

Fig. 4.0Create Chart · Manual mode · targen parameters · Expert Options expandedPresets: Default

For extended-gamut printers (e.g. CMYK + Orange + Green + Light Cyan), the Add/Remove Colorant (-D) expert option supports up to 11 cascading slots — enabling one slot reveals the next. All values and enabled states are saved with presets and Save Defaults.

The TIFF preview on the right displays RGB, CMYK, and extended-gamut TIFFs with up to 11 ink channels. CMYK is converted to sRGB using US Web Coated SWOP v2 for accurate colour rendering. A .channels.json sidecar written alongside each chart file preserves ink-channel order across sessions so re-loading always shows the correct colours.

Instrument support

Paper sizes

A2 · A3+ · A3 · A3 Landscape · A4 · A4 Landscape · Tabloid (11×17) · Legal · Letter · Letter Landscape · 8×10" · 5×7" · 4×6" · Custom (W×H mm)

Photo formats (5×7" and 4×6") are hidden for i1Pro 3 Plus in Guided mode — patch counts are too low for a usable profile at those sizes. The Custom option reveals two numeric fields whose values are passed directly to printtarg as -pWxH.

4.2 · Print Chart

Detected printers come straight from CUPS via the pycups API (more reliable across locales than parsing lpstat). ChromIQ exposes only the print options that actually exist on your specific driver — options unlock sequentially so you can't pick incompatible combinations (Epson EPIJ rules, PPD UIConstraints, and generic keyword heuristics are all honoured).

PostScript printing pipeline

ChromIQ sends charts via a PostScript Level 2/3 pipeline rather than raw TIFF. The PS document embeds device-dependent colour spaces (/DeviceRGB, /DeviceCMYK, /DeviceN) and the %cupsJobTicket: cups-disable-cmm header, so CUPS and macOS ColorSync apply zero colour transforms — the pixel values that leave the app are exactly the values the spectrophotometer will measure. 16-bit profiling targets (printtarg -T300) are printed as PostScript Level 3 with 16-bit colour components for printers and RIPs with a true 16-bit pipeline.

CMYK and multi-channel (DeviceN) profiling targets with 4–17 channels are fully supported — previously all targets were force-cast to DeviceRGB by CUPS, corrupting CMYK and multi-ink patch data.

AirPrint / driverless fallback

Some printers (e.g. Epson EcoTank via AirPrint) reject PostScript at the CUPS level. ChromIQ detects this automatically and retries with the original TIFF using colour-space-aware CUPS raster options (cupsColorSpace, ColorModel) — bypassing ColorSync without requiring PostScript support on the printer. No user action needed.

When a printer has no configurable driver options (AirPrint/driverless), a prominent notice explains how to reinstall the printer with the manufacturer's native PPD driver for best results.

Native macOS printer dialog optional

Enable Preferences → Behaviour → Use default macOS printer dialog to replace the built-in PostScript/CUPS pipeline with the standard macOS print sheet. When active, the tab shows per-brand instructions for disabling colour management in the driver panel (Epson, Canon, HP, and others). Defaults to off — existing behaviour is unchanged unless explicitly enabled.

4.3 · Measure

The Measure tab wraps chartread and surfaces its full option set as checkboxes: Disable bidirectional strip recognition (-B), Suppress warning messages (-S), Skip initial calibration (-N), Patch-by-patch mode (-p), High-resolution spectral (-H), Patch consistency tolerance (-T, enabled at 0.7 by default), and L*a*b* / XYZ output switches.

Spectral filter type (-F) lets you override the measurement condition used by the instrument: None (M0), D50 (M1), D65, UV Cut (M2), or Polarizing (M3). Disabled by default; D50 (M1) is pre-selected when you enable it — use M1 for ISO 13655-compliant measurements with OBA-containing papers.

The tab handles every runtime condition chartread raises: calibration prompts, wrong-strip warnings, unexpected colour-response warnings, "no instrument detected", strip-read retries, and a completion dialog when all strips are done. All measurement controls are locked while chartread is running.

In Guided mode, the Measurement Instrument section, Skip Initial Calibration, Patch-by-Patch Mode, and Additional Options are hidden — the panel stays focused on the essential strip-by-strip workflow. Manual mode also exposes refinement options: Refine existing measurement (-r) and a strip file picker, which activate guided strip-by-strip navigation when a strips file is loaded.

Fig. 4.1Measure · Manual mode · full chartread options · Spectral filter type (-F) visibleAdditional Options expanded

4.4 · Build Profile

Exposes the full colprof option surface, organised into panels:

Media attributes (-Z) — new in v3.0.0-beta.10

Two controls appear in the Color Science section of both Guided and Manual modes (and in the Calibration tab's Build Profile module). Three additional controls are available in Manual mode only.

All selections default to ArgyllCMS defaults — no -Z flag is emitted unless you explicitly change a value. Settings are persisted via Save as Defaults (guided and manual) and user presets (manual).

Optional calibration workflow Preferences → Behaviour

Enable Enable calibration options in Preferences → Behaviour to unlock the full printcal → applycal printer calibration workflow. Off by default — most users profiling consumer inkjet printers do not need it. When enabled:

• Guided panels are hidden across all tabs; Tab 4 is renamed Calibration & Profiling.
• A three-module selector appears: Create Calibration File / Build Profile / Apply Calibration.
• Create Calibration File runs printcal to generate a .cal curve file. Supports per-channel target overrides for C/M/Y/K and extended channels (Ch4–Ch7), calibration metadata embedding, imitation target mode (-I), and a dry-run checkbox (-d). On success a dialog offers Go to Create Chart → with the .cal path pre-filled.
• Apply Calibration runs applycal to bake, remove, or verify calibration curves on an ICC profile. A result dialog offers Install on this Mac.
• Measurements whose filename starts with cal_ are automatically routed to Create Calibration File instead of Build Profile.
• The Build Profile result dialog gains an Apply Calibration → button with the ICC path pre-filled.

Fig. 4.4Calibration & Profiling · Create Calibration File module · printcal optionsEnable in Preferences → Behaviour

Fig. 4.2Build Profile · Manual mode · Profile Built dialog · printer test.icc savedInstall on this Mac · Check Profile Quality · Done

4.5 · Check & Refine

Wraps profcheck and adds a human-readable quality report on top. Two metrics drive the grade: average ΔE and peak ΔE. A profile with an excellent average but a handful of high-error outlier patches is graded accordingly — the report tells you which metric is limiting the grade.

When patches exceed your ΔE threshold, ChromIQ proposes re-measuring only those strips (the refinement flow). The "start over" recommendation fires only when more than 50% of individual patches exceed the threshold or more than 75% of strips are flagged — patch-based logic that avoids false alarms on small charts.

Fig. 4.3Check & Refine · Manual mode · Profile Quality Assessment · ExcellentΔE_avg 0.26 · Peak ΔE 0.80

Settings & configuration.

All preferences are stored via QSettings and survive updates and reinstalls.

Preferences dialog

Open with ChromIQ ▸ Preferences or ⌘+,. The following settings live here:

Behaviour settings

Where things live

Saving defaults per-tab

Every tab has a Save as Defaults button. Click it to persist the current combination of instrument, paper, flags, and advanced options as the starting point for the next session. Useful when you have a favourite workflow for a specific printer/paper pair.

Keyboard shortcuts

Fig. 5.0Preferences dialog · ArgyllCMS path · Behaviour toggles⌘,

Troubleshooting
& FAQ.

The common failure modes and the fixes that actually work. When none of these help, check ~/Library/Logs/ChromIQ/chromiq.log — the exact Argyll command and its output are always in there.

Known limitations

• Print colour management behaviour across the full matrix of driver/printer combinations is still under active testing.
• Advanced gamut-mapping options (custom intents, FWA combinations) have not been exercised on every instrument/paper combination — stick to defaults for production work until you've verified.
• Some spectrophotometer models need extra calibration steps not yet surfaced in ChromIQ's UI — follow the prompts chartread prints in the log pane.
• Windows printing — the CUPS/PostScript pipeline is not available on Windows. Colour management must be disabled manually in the printer driver before printing a profiling target.
• Linux — not currently supported.