Full Gamut

#Overview

Full Gamut is Calibration Flow's extended separation mode. Where the Aquaprint CMYK works with four negatives (CMYK), Full Gamut produces six — by adding Orange and Green — or seven if you enable the experimental Violet. The goal is to recover the saturated colors that CMYK can't reproduce: a vivid pyrrole orange, a deep phthalo green, a magenta leaning toward blue.

The mode is aimed at anyone already practicing Aquaprint Color in CMYK who wants to push further. It's an extension, not a replacement. You keep using the non-toxic Vision Picturale recipes, but you output two or three additional negatives on top of the CMYK base. The benefit shows on subjects rich in saturated colors — flowers, autumn landscapes, vivid fabrics, fruit.

#Difference from CMYK mode

CMYK gives you consistent but bounded colors. Full Gamut gives you access to the zones the Cyan-Magenta-Yellow triangle doesn't touch. The trade-off is more layers to print, more registration to hold, more pigments to manage in the workshop.

#Choosing between 6c and 7c

6c mode is enough in most cases. Adding Orange and Green solves 80% of CMYK's limited-gamut problem. Warm oranges, natural greens, saturated yellows become faithful. It's the recommended mode to start out in extended gamut.

7c mode brings the deep magentas and violets. If you work on subjects rich in violet (grapes, lavender, orchids, dyed clothing), the PV23 Violet channel fills the last missing zone of the gamut.

Experimental V1 status for 7c. The Violet channel hasn't been chemically validated yet. The algorithm knows where to place it, but the Violet gum recipe isn't finalized at Vision Picturale. Use it to test, not in production.

#The Black level slider (Black Generation)

The Black level slider controls Gray Component Replacement — how much gray is replaced by pure Black instead of the triple CMY overlap. It's a critical parameter in Aquaprint because dichromate gum has a physical limit on cumulative thickness.

Five positions, Photoshop equivalents in parentheses:

• None (GCR 0%) — No separate black. Black is born solely from the CMY overlap. Rich in nuance, but maximum cumulative thickness.
• Light (GCR 25%) — A touch of black in the deep shadows. Classic compromise.
• Medium (GCR 50%) — Moderate replacement. Black takes a substantial share of the dark zones. Default preset.
• Heavy (GCR 75%) — Black carries most of the dark zones. Sharply reduces cumulative thickness.
• Maximum (GCR 100%, UCR equivalent) — Under-color removed to the maximum. The gray and dark zones rest almost exclusively on the Black channel.

Physical impact. The further you push the slider toward Maximum, the less gum you accumulate in the dark zones. That's what keeps the layer from cracking on drying or lifting off in the wash. On subjects with strong shadows or sensitive paper, Heavy or Maximum are almost mandatory.

#Full workflow

#Step 1 — Generate the calibration target

Target tab, hexagonal 6c or 7c format, A4 (test) or A3 (production), 300 dpi minimum, download the PNG.

#Step 2 — Print on transparency

Inkjet transparency, pigment-ink printer, no color management. Same method as a CMYK target.

#Step 3 — Print the target in Aquaprint

Follow the order Y → M → C → K → O → G → (V). One pigment at a time, full drying between each layer, a single final wash.

#Step 4 — Photograph the printed target

Even lighting (daylight or softbox), no cast shadows, your white-balance card visible in the frame.

#Step 5 — Import the photo into CF

Import a photo button. Calibration Flow detects the target, crops it, runs the patch analysis.

#Step 6 — Configure Full Gamut

Type tab → FULL GAMUT button. Choose 6c or 7c, set the Black level slider. The preview thumbnails update in real time.

#Step 7 — Generate the HD negatives

Click each thumbnail to switch to HD. The channel displays fullscreen, downloadable as PNG. Repeat for all 6 or 7 channels.

#Step 8 — Print and develop

Same steps as the target. The calibration from step 4 applies automatically to each negative.

#Practical tips

#Aquaprint layer order

Y → M → C → K → O → G → (V). The order isn't arbitrary. You start with Yellow (the most transparent), you finish with Violet (the most opaque). Black comes after CMY to densify the shadows once the color base is laid down. Orange and Green saturate locally without interfering with the main separation. Full drying between each layer — 12 to 24 hours depending on the workshop.

#Cumulative thickness

Dichromate gum has a physical limit. Beyond five or six saturated layers overlapped, the layer cracks on drying or lifts off in the wash. That's why the Black level slider matters so much — a Heavy or Maximum GCR reduces thickness in the dark zones and lets you hold 7 layers. If your prints crack, move the slider up a notch and remake a test target.

#Choice of pigments

• PO73 Pyrrole Orange — Kremer, Sennelier, Schmincke. Saturated orange-red zone.
• PG7 Phthalo Green — same suppliers. Deep, stable green.
• PV23 Dioxazine Violet (7c experimental) — Kremer, VP recipe not finalized.

Use exclusively the reformulated Vision Picturale recipes (non-toxic). No ammonium dichromate.

#When Full Gamut is useless

• Black-and-white photos. A single negative is enough. Stay on simple Negative.
• Photos poor in orange/green/violet. Studio portrait, still life in muted tones, winter landscape — CMYK already covers everything.
• Photos rich in saturated colors. Flowers, fruit, autumn landscapes, dyed fabrics — this is where Full Gamut comes into its own.

#Current V1 limitations

• Heuristic LCh algorithm. Separation by fixed hue centers in CIELCh. An approximation. True ICC calibration (a measured DeviceN profile) arrives in V2 after Phase 3 lab tests.
• Experimental 7c mode. Violet channel not chemically validated yet. VP recipe in progress.
• Total Ink Limit fixed at 380%. The app automatically applies a cap of 380% cumulative ink (SWOP coated equivalent): if the sum of the channels (C + M + Y + K + O + G + Vt in 7c) exceeds that threshold on a pixel, all channels are normalized proportionally to stay under the limit. This keeps highly saturated 7c zones from cracking on drying. The value is configurable on the engine side (the

  inkLimit

  option, down to 320% on fragile cotton, up to 400% on yupo), but not yet exposed in the UI — V2 will add a dedicated slider.
• ICC profile in memory only. The ICC profile loaded in the Full Gamut sheet is stored in memory (

  window.__loadedIccProfile

  ), not persisted. You have to reload it every session — on page reload, it's lost. localStorage/IndexedDB persistence will come in V2.
• Manual layer order. No batch export sorted in the Y → M → C → K → O → G → (V) order.

#Going further

• Color Venn — calibration target — the 3-overlapping-circle target tool, complementary for classic CMYK calibration.
• Luminograph code — how to unlock the advanced functions, Full Gamut among them.
• CMYK four-color printing — the four-channel mode, to master before moving to Full Gamut.

#FAQ

Q: Why 6 negatives instead of 4? A: The CMYK triangle covers a limited part of the visible gamut. By adding Orange and Green, you access the saturated oranges and deep greens that CMYK can't reproduce.

Q: My print cracks, what do I do? A: You're accumulating too much gum. Move the Black level slider to Heavy or Maximum to reduce thickness in the dark zones. Also check that your paper can hold 6 or 7 layers.

Q: 7c mode (Violet) doesn't work well. A: Experimental V1 status. The Violet gum recipe isn't finalized yet by Vision Picturale. Stay on 6c in production until V2 ships.

Q: Do I have to redo the whole calibration to move from CMYK to Full Gamut? A: Yes. The 6c target contains the Orange and Green patches that don't exist in the CMYK target. Without a measured 6c target, the algorithm doesn't know where to place the added pigments on your process.

Q: Does Full Gamut work with Charcoal Color? A: No. Full Gamut is built for Aquaprint, where each layer is applied separately. Deep Charcoal Color prints three CMY layers by successive transfer — a different workflow, not documented yet.

Q: When will V2 with ICC calibration ship? A: No public date. V2 depends on the Phase 3 lab tests at Vision Picturale (chemical validation of the non-toxic recipes, spectrophotometric measurement). We're aiming for late 2026.

#Glossary

• Gamut — the set of colors a process can reproduce. Cyanotype = very limited; Aquaprint CMYK = most of sRGB; Full Gamut = extended toward saturated oranges, greens, violets.
• CIELCh — a perceptual color space (Luminance, Chroma, Hue). Used by the V1 algorithm to place each pigment at its optimal hue center.
• GCR (Gray Component Replacement) — a technique that replaces the CMY overlap with pure Black in the dark zones. Reduces cumulative thickness. Controlled by the Black level slider.
• DeviceN — ICC profile format for color spaces with N channels. What V2 will use for true ICC calibration.
• Pigment Index (PO73, PG7, PV23) — standardized international code. PO73 = Pyrrole Orange, PG7 = Phthalo Green, PV23 = Dioxazine Violet.
• Hue center — the hue angle of a pigment in LCh space, measured on real pigment samples (handprint.com, Bruce MacEvoy, CIECAM02). PO73 ≈ 37°, PG7 ≈ 178° (Phthalo is actually cyan-green, not primary green — hence the gap with the HSV intuition at 120°), PV23 ≈ 299°.