# S-52 Colour Palette Reference

Source: IHO S-52 Presentation Library, Edition 4.0 (and OpenCPN chartsymbols.xml)

## DAY_BRIGHT Palette (primary display mode)

| Token    | R   | G   | B   | Usage / Meaning |
|----------|-----|-----|-----|-----------------|
| NODTA    | 163 | 180 | 193 | No-data area (unknown / outside coverage) |
| CHBLK    |   0 |   0 |   0 | Chart black — text, lines, symbol outlines |
| CHRED    | 220 |  64 |  64 | Chart red — port lateral, danger highlight |
| CHGRN    |  64 | 160 |  64 | Chart green — starboard lateral |
| CHYLW    | 200 | 185 |  30 | Chart yellow — special marks, caution areas |
| CHMGD    | 170 |  82 | 170 | Chart magenta — traffic lanes |
| CHBLU    |  67 | 128 | 185 | Chart blue — general water fill |
| CHDRD    | 128 |   0 |   0 | Chart dark red |
| CHDGD    |   0 |  80 |   0 | Chart dark green |
| LITRD    | 255 |  64 |  64 | Light sector — red arc |
| LITGN    |  64 | 200 |  64 | Light sector — green arc |
| LITYW    | 255 | 220 |  64 | Light sector — yellow/white arc |
| LANDA    | 200 | 190 | 150 | Land area fill (S-52 standard) |
| LNDG1    | 185 | 175 | 135 | Land gradient shade 1 (darker) |
| LNDG2    | 215 | 205 | 165 | Land gradient shade 2 (lighter) |
| DEPVS    | 181 | 217 | 230 | Very shallow depth area (< safety contour) |
| DEPDW    |  83 | 161 | 198 | Deep water area (> deep contour) |
| DEPMD    | 148 | 195 | 220 | Medium depth area |
| DEPSH    | 181 | 217 | 230 | Shallow depth area |
| DEPIT    | 144 | 195 | 223 | Intertidal area |
| RADHI    | 148 | 195 | 220 | Radar highlights (not used on screen) |
| RADLO    | 148 | 195 | 220 | Radar low |
| UNDET    | 163 | 180 | 193 | Undetermined quality |
| SHIPS    |   0 |   0 |   0 | Own ship symbol |
| PLRTE    | 220 |  10 |  10 | Planned route |
| APLRT    | 255 | 165 |   0 | Active alert / alarm |
| UINFD    | 235 | 250 | 235 | User info fill (dim green) |
| UINFR    | 235 | 230 | 230 | User info fill (dim red) |
| UINFG    | 230 | 245 | 230 | User info fill (green) |
| UINFO    | 255 | 240 | 210 | User info fill (orange) |
| UINFB    | 220 | 230 | 250 | User info fill (blue) |
| UINFF    | 180 | 180 | 180 | User info fill (grey) |
| CHGRD    | 204 | 204 | 204 | Grid / graticule lines |
| CHGRF    | 180 | 180 | 180 | Grid lines (faint) |
| CURSOR   | 255 | 220 |   0 | Cursor highlight |
| ECHMRK   | 255 | 140 |   0 | Echo sounder mark |
| SNDG1    |   0 |   0 |   0 | Sounding value colour (shoal) |
| SNDG2    |   0 |   0 | 128 | Sounding value colour (deep) |
| SCLBR    |   0 |   0 |   0 | Scale bar |

---

## DAY_BLACKBACK Palette (high-contrast / night mode)

Key differences vs DAY_BRIGHT:

| Token    | R   | G   | B   |
|----------|-----|-----|-----|
| NODTA    |  40 |  40 |  40 |
| CHBLK    | 255 | 255 | 255 |
| LANDA    |  90 |  90 |  90 |
| DEPVS    |  20 |  40 |  60 |
| DEPDW    |   0 |  10 |  30 |
| LITRD    | 255 |  80 |  80 |
| LITGN    |  80 | 255 |  80 |
| LITYW    | 255 | 255 | 100 |

---

## DUSK Palette

| Token    | R   | G   | B   |
|----------|-----|-----|-----|
| NODTA    | 100 | 100 | 100 |
| CHBLK    | 220 | 220 | 220 |
| LANDA    | 115 | 110 |  90 |
| DEPVS    |  80 |  90 | 100 |
| DEPDW    |  50 |  60 |  80 |
| LITRD    | 200 |  50 |  50 |
| LITGN    |  50 | 180 |  50 |
| LITYW    | 210 | 180 |  50 |

---

## NIGHT Palette

| Token    | R   | G   | B   |
|----------|-----|-----|-----|
| NODTA    |  20 |  20 |  20 |
| CHBLK    | 160 | 160 | 160 |
| LANDA    |  50 |  50 |  40 |
| DEPVS    |   0 |  20 |  40 |
| DEPDW    |   0 |   5 |  15 |
| LITRD    | 180 |  30 |  30 |
| LITGN    |  30 | 150 |  30 |
| LITYW    | 180 | 150 |  30 |

---

## Depth Area Shading — Standard S-52 Scheme

S-52 uses 4 depth zones selectable by user safety contour settings:

| Zone                      | Token  | Description |
|---------------------------|--------|-------------|
| Depth < safety contour    | DEPVS  | Dangerous shoal — usually lightest blue |
| safety ≤ depth < deep     | DEPMD  | Intermediate depth |
| depth ≥ deep contour      | DEPDW  | Safe deep water — darkest blue |
| Intertidal                | DEPIT  | Dries at low water |

---

## AidsMonitoring Usage Notes

- Light arcs rendered on canvas use: LITRD (#ff4040), LITGN (#40c840), LITYW (#ffd440)
- Land fill uses LANDA (#c8be96 in DAY_BRIGHT)
- Depth soundings: SNDG1 for shoal values, SNDG2 for deeper values
- Cardinal marks always black+yellow regardless of region
- Special marks: CHYLW
- Isolated danger: CHRED + CHBLK bands
- Safe water: CHRED + white (CHBLK=0 background)
