PPU palettes
The NES has a limited selection of color outputs. A 6-bit value in the palette memory area corresponds to one of 64 outputs. The emphasis bits of the PPUMASK register ($2001) provide an additional color modifier.
For more information on how the colors are generated on an NTSC NES, see: NTSC video. For additional information on how the colors are generated on a PAL NES, see: PAL video.
Memory Map
The palette for the background runs from VRAM $3F00 to $3F0F; the palette for the sprites runs from $3F10 to $3F1F. Each color takes up one byte.
Address | Purpose |
---|---|
$3F00 | Universal background color |
$3F01-$3F03 | Background palette 0 |
$3F05-$3F07 | Background palette 1 |
$3F09-$3F0B | Background palette 2 |
$3F0D-$3F0F | Background palette 3 |
$3F11-$3F13 | Sprite palette 0 |
$3F15-$3F17 | Sprite palette 1 |
$3F19-$3F1B | Sprite palette 2 |
$3F1D-$3F1F | Sprite palette 3 |
Each palette has three colors. Each 16x16 pixel area of the background can use the backdrop color and the three colors from one of the four background palettes. The choice of palette for each 16x16 pixel area is controlled by bits in the attribute table at the end of each nametable. Each sprite can use the three colors from one of the sprite palettes. The choice of palette is in attribute 2 of each sprite (see PPU OAM).
Addresses $3F04/$3F08/$3F0C can contain unique data, though these values are not used by the PPU when normally rendering (since the pattern values that would otherwise select those cells select the backdrop color instead). They can still be shown using the background palette hack, explained below.
Addresses $3F10/$3F14/$3F18/$3F1C are mirrors of $3F00/$3F04/$3F08/$3F0C. Note that this goes for writing as well as reading. A symptom of not having implemented this correctly in an emulator is the sky being black in Super Mario Bros., which writes the backdrop color through $3F10.
Thus, indices into the palette are formed as follows:
43210 ||||| |||++- Pixel value from tile data |++--- Palette number from attribute table or OAM +----- Background/Sprite select
As in some second-generation game consoles, values in the NES palette are based on hue and brightness:
76543210 |||||||| ||||++++- Hue (phase, determines NTSC/PAL chroma) ||++----- Value (voltage, determines NTSC/PAL luma) ++------- Unimplemented, reads back as 0
Hue $0 is light gray, $1-$C are blue to red to green to cyan, $D is dark gray, and $E-$F are mirrors of $1D (black).
It works this way because of the way colors are represented in a composite NTSC or PAL signal, with the phase of a color subcarrier controlling the hue. For details regarding signal generation and color decoding, see NTSC video.
The canonical code for "black" is $0F or $1D.
The 2C03 RGB PPU used in the PlayChoice-10 and Famicom Titler renders hue $D as black, not dark gray. The 2C04 PPUs used in many Vs. System arcade games have completely different palettes as a copy protection measure.
Palettes
The 2C02 (NTSC) and 2C07 (PAL) PPU is used to generate an analog composite video signal. These were used in most home consoles.
The 2C03, 2C04, and 2C05, on the other hand, all output analog red, green, blue, and sync (RGBS) signals. The sync signal contains horizontal and vertical sync pulses in the same format as an all-black composite signal. Each of the three video channels uses a 3-bit DAC driven by a look-up table in a 64x9-bit ROM inside the PPU. The look-up tables (one digit for each of red, green, and blue, in order) are given below.
RGB PPUs were used mostly in arcade machines (e.g. Vs. System, Playchoice 10), as well as the Sharp Famicom Titler.
2C02
The RF Famicom, AV Famicom, NES (both front- and top-loading), and the North American version of the Sharp Nintendo TV use the 2C02 PPU. Unlike some other consoles' video circuits, the 2C02 does not generate RGB video and then encode that to composite. Instead it generates NTSC video directly in the composite domain, decoded by the television receiver into RGB to drive its picture tube.
Do not use color $0D. It results in a "blacker than black" signal that may cause problems for some TVs.
Further details on $0D and its effects can be found here. |
Most emulators can use a predefined palette, such as one commonly stored in common .pal format, in which each triplet represents the sRGB color that results from decoding a large flat area with a given palette value. The following palette was generated using Persune's palette generator v0.3.6 with the following arguments: palgen-persune.py -rfc "ITU-R BT.709" -phs -5.0 -blp 0.0 -o 2C02G.pal
$00 | $01 | $02 | $03 | $04 | $05 | $06 | $07 | $08 | $09 | $0A | $0B | $0C | $0E | $0F | |
$10 | $11 | $12 | $13 | $14 | $15 | $16 | $17 | $18 | $19 | $1A | $1B | $1C | $1D | $1E | $1F |
$20 | $21 | $22 | $23 | $24 | $25 | $26 | $27 | $28 | $29 | $2A | $2B | $2C | $2D | $2E | $2F |
$30 | $31 | $32 | $33 | $34 | $35 | $36 | $37 | $38 | $39 | $3A | $3B | $3C | $3D | $3E | $3F |
Other tools for generating a palette include one by Bisqwit and one by Drag. These simulate generating a large area of one flat color and then decoding that with the adjustment knobs set to various settings.
2C07
The PAL PPU (2C07) generates a composite PAL video signal, which has a -15 degree hue shift relative to the 2C02 due to a different colorburst reference phase generated by the PPU ($x7 rather than $x8), in addition to the PAL colorburst phase being defined as -U ± 45 degrees. The following palette was generated using Persune's palette generator with the following arguments: palgen-persune.py -rfc "ITU-R BT.709" -blp 0.0 -cbr 7 -pal -o 2C07.pal
$00 | $01 | $02 | $03 | $04 | $05 | $06 | $07 | $08 | $09 | $0A | $0B | $0C | $0E | $0F | |
$10 | $11 | $12 | $13 | $14 | $15 | $16 | $17 | $18 | $19 | $1A | $1B | $1C | $1D | $1E | $1F |
$20 | $21 | $22 | $23 | $24 | $25 | $26 | $27 | $28 | $29 | $2A | $2B | $2C | $2D | $2E | $2F |
$30 | $31 | $32 | $33 | $34 | $35 | $36 | $37 | $38 | $39 | $3A | $3B | $3C | $3D | $3E | $3F |
2C03 and 2C05
This palette is intentionally similar to the NES's standard palette, but notably is missing the greys in entries $2D and $3D.
The 2C03 is used in Vs. Duck Hunt, Vs. Tennis, all PlayChoice games, the Famicom Titler, and the Famicom TV.
The 2C05 is used in some later Vs. games as a copy protection measure.
Both have been used in RGB mods for the NES, as a circuit implementing A0' = A0 xor (A1 nor A2)
can swap PPUCTRL and PPUMASK to make a 2C05 behave as a 2C03.
The formula for mapping the DAC integer channel value to 8-bit per channel color is C = 255 * DAC / 7
.
$x0 | $x1 | $x2 | $x3 | $x4 | $x5 | $x6 | $x7 | $x8 | $x9 | $xA | $xB | $xC | $xD | $xE | $xF | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
$0x | 333 | 014 | 006 | 326 | 403 | 503 | 510 | 420 | 320 | 120 | 031 | 040 | 022 | 000 | 000 | 000 |
$1x | 555 | 036 | 027 | 407 | 507 | 704 | 700 | 630 | 430 | 140 | 040 | 053 | 044 | 000 | 000 | 000 |
$2x | 777 | 357 | 447 | 637 | 707 | 737 | 740 | 750 | 660 | 360 | 070 | 276 | 077 | 000 | 000 | 000 |
$3x | 777 | 567 | 657 | 757 | 747 | 755 | 764 | 772 | 773 | 572 | 473 | 276 | 467 | 000 | 000 | 000 |
Note that some of the colors are duplicates: $0B and $1A = 040, $2B and $3B = 276.
Kevtris's dumped palettes imply that the monochrome bit has unique function on the 2C03 and 2C05: instead of just using the leftmost column of the palette (and forcing the lower four bits to zero), instead the top two bits index into a palette with colors: 000, 333, 777, 777. Given that the 2C04 does not do this, this exception feels weird, and corroboration would be appreciated.
2C04
All four 2C04 PPUs contain the same master palette, but in different permutations. It's almost a superset of the 2C03/5 palette, adding four greys, six other colors, and making the bright yellow more pure.
Note that using the greyscale bit in PPUMASK will remap the palette by index, not by color. This means that with the scrambled palettes, each row will remap to the colors in the $0X column for that 2C04 version.
Visualization tool: RGB PPU Palette Converter
No version of the 2C04 was ever made with the below ordering, but it shows the similarity to the 2C03:
333 | 014 | 006 | 326 | 403 | 503 | 510 | 420 | 320 | 120 | 031 | 040 | 022 | 111 | 003 | 020 |
555 | 036 | 027 | 407 | 507 | 704 | 700 | 630 | 430 | 140 | 040 | 053 | 044 | 222 | 200 | 310 |
777 | 357 | 447 | 637 | 707 | 737 | 740 | 750 | 660 | 360 | 070 | 276 | 077 | 444 | 000 | 000 |
777 | 567 | 657 | 757 | 747 | 755 | 764 | 770 | 773 | 572 | 473 | 276 | 467 | 666 | 653 | 760 |
The PPUMASK monochrome bit has the same implementation as on the 2C02, and so it has an unintuitive effect on the 2C04 PPUs; rather than forcing colors to grayscale, it instead forces them to the first column.
RP2C04-0001
MAME's source claims that Baseball, Freedom Force, Gradius, Hogan's Alley, Mach Rider, Pinball, and Platoon require this palette.
755,637,700,447,044,120,222,704,777,333,750,503,403,660,320,777 357,653,310,360,467,657,764,027,760,276,000,200,666,444,707,014 003,567,757,070,077,022,053,507,000,420,747,510,407,006,740,000 000,140,555,031,572,326,770,630,020,036,040,111,773,737,430,473
$x0 | $x1 | $x2 | $x3 | $x4 | $x5 | $x6 | $x7 | $x8 | $x9 | $xA | $xB | $xC | $xD | $xE | $xF | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
$0x | 755 | 637 | 700 | 447 | 044 | 120 | 222 | 704 | 777 | 333 | 750 | 503 | 403 | 660 | 320 | 777 |
$1x | 357 | 653 | 310 | 360 | 467 | 657 | 764 | 027 | 760 | 276 | 000 | 200 | 666 | 444 | 707 | 014 |
$2x | 003 | 567 | 757 | 070 | 077 | 022 | 053 | 507 | 000 | 420 | 747 | 510 | 407 | 006 | 740 | 000 |
$3x | 000 | 140 | 555 | 031 | 572 | 326 | 770 | 630 | 020 | 036 | 040 | 111 | 773 | 737 | 430 | 473 |
RP2C04-0002
MAME's source claims that Castlevania, Mach Rider (Endurance Course), Raid on Bungeling Bay, Slalom, Soccer, Stroke & Match Golf (both versions), and Wrecking Crew require this palette.
000,750,430,572,473,737,044,567,700,407,773,747,777,637,467,040 020,357,510,666,053,360,200,447,222,707,003,276,657,320,000,326 403,764,740,757,036,310,555,006,507,760,333,120,027,000,660,777 653,111,070,630,022,014,704,140,000,077,420,770,755,503,031,444
$x0 | $x1 | $x2 | $x3 | $x4 | $x5 | $x6 | $x7 | $x8 | $x9 | $xA | $xB | $xC | $xD | $xE | $xF | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
$0x | 000 | 750 | 430 | 572 | 473 | 737 | 044 | 567 | 700 | 407 | 773 | 747 | 777 | 637 | 467 | 040 |
$1x | 020 | 357 | 510 | 666 | 053 | 360 | 200 | 447 | 222 | 707 | 003 | 276 | 657 | 320 | 000 | 326 |
$2x | 403 | 764 | 740 | 757 | 036 | 310 | 555 | 006 | 507 | 760 | 333 | 120 | 027 | 000 | 660 | 777 |
$3x | 653 | 111 | 070 | 630 | 022 | 014 | 704 | 140 | 000 | 077 | 420 | 770 | 755 | 503 | 031 | 444 |
RP2C04-0003
MAME's source claims that Balloon Fight, Dr. Mario, Excitebike (US), Goonies, and Soccer require this palette.
507,737,473,555,040,777,567,120,014,000,764,320,704,666,653,467 447,044,503,027,140,430,630,053,333,326,000,006,700,510,747,755 637,020,003,770,111,750,740,777,360,403,357,707,036,444,000,310 077,200,572,757,420,070,660,222,031,000,657,773,407,276,760,022
$x0 | $x1 | $x2 | $x3 | $x4 | $x5 | $x6 | $x7 | $x8 | $x9 | $xA | $xB | $xC | $xD | $xE | $xF | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
$0x | 507 | 737 | 473 | 555 | 040 | 777 | 567 | 120 | 014 | 000 | 764 | 320 | 704 | 666 | 653 | 467 |
$1x | 447 | 044 | 503 | 027 | 140 | 430 | 630 | 053 | 333 | 326 | 000 | 006 | 700 | 510 | 747 | 755 |
$2x | 637 | 020 | 003 | 770 | 111 | 750 | 740 | 777 | 360 | 403 | 357 | 707 | 036 | 444 | 000 | 310 |
$3x | 077 | 200 | 572 | 757 | 420 | 070 | 660 | 222 | 031 | 000 | 657 | 773 | 407 | 276 | 760 | 022 |
RP2C04-0004
MAME's source claims that Clu Clu Land, Excitebike (Japan), Ice Climber (both versions), and Super Mario Bros. require this palette.
430,326,044,660,000,755,014,630,555,310,070,003,764,770,040,572 737,200,027,747,000,222,510,740,653,053,447,140,403,000,473,357 503,031,420,006,407,507,333,704,022,666,036,020,111,773,444,707 757,777,320,700,760,276,777,467,000,750,637,567,360,657,077,120
$x0 | $x1 | $x2 | $x3 | $x4 | $x5 | $x6 | $x7 | $x8 | $x9 | $xA | $xB | $xC | $xD | $xE | $xF | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
$0x | 430 | 326 | 044 | 660 | 000 | 755 | 014 | 630 | 555 | 310 | 070 | 003 | 764 | 770 | 040 | 572 |
$1x | 737 | 200 | 027 | 747 | 000 | 222 | 510 | 740 | 653 | 053 | 447 | 140 | 403 | 000 | 473 | 357 |
$2x | 503 | 031 | 420 | 006 | 407 | 507 | 333 | 704 | 022 | 666 | 036 | 020 | 111 | 773 | 444 | 707 |
$3x | 757 | 777 | 320 | 700 | 760 | 276 | 777 | 467 | 000 | 750 | 637 | 567 | 360 | 657 | 077 | 120 |
Games compatible with multiple different PPUs
Some games don't require that arcade owners have the correct physical PPU.
At the very least, the following games use some of the DIP switches to support multiple different PPUs:
- Atari RBI Baseball
- Battle City
- Star Luster
- Super Sky Kid
- Super Xevious
- Tetris (Tengen)
- TKO Boxing
LUT approach
Emulator authors may implement the 2C04 variants as a LUT indexing the "ordered" palette. This has the added advantage of being able to use preexisting .pal files if the end user wishes to do so.
Repeating colors such as 000 and 777 may index into the same entry of the "ordered" palette, as this is functionally identical.
const unsigned char PaletteLUT_2C04_0001 [64] ={ 0x35,0x23,0x16,0x22,0x1C,0x09,0x1D,0x15,0x20,0x00,0x27,0x05,0x04,0x28,0x08,0x20, 0x21,0x3E,0x1F,0x29,0x3C,0x32,0x36,0x12,0x3F,0x2B,0x2E,0x1E,0x3D,0x2D,0x24,0x01, 0x0E,0x31,0x33,0x2A,0x2C,0x0C,0x1B,0x14,0x2E,0x07,0x34,0x06,0x13,0x02,0x26,0x2E, 0x2E,0x19,0x10,0x0A,0x39,0x03,0x37,0x17,0x0F,0x11,0x0B,0x0D,0x38,0x25,0x18,0x3A }; const unsigned char PaletteLUT_2C04_0002 [64] ={ 0x2E,0x27,0x18,0x39,0x3A,0x25,0x1C,0x31,0x16,0x13,0x38,0x34,0x20,0x23,0x3C,0x0B, 0x0F,0x21,0x06,0x3D,0x1B,0x29,0x1E,0x22,0x1D,0x24,0x0E,0x2B,0x32,0x08,0x2E,0x03, 0x04,0x36,0x26,0x33,0x11,0x1F,0x10,0x02,0x14,0x3F,0x00,0x09,0x12,0x2E,0x28,0x20, 0x3E,0x0D,0x2A,0x17,0x0C,0x01,0x15,0x19,0x2E,0x2C,0x07,0x37,0x35,0x05,0x0A,0x2D }; const unsigned char PaletteLUT_2C04_0003 [64] ={ 0x14,0x25,0x3A,0x10,0x0B,0x20,0x31,0x09,0x01,0x2E,0x36,0x08,0x15,0x3D,0x3E,0x3C, 0x22,0x1C,0x05,0x12,0x19,0x18,0x17,0x1B,0x00,0x03,0x2E,0x02,0x16,0x06,0x34,0x35, 0x23,0x0F,0x0E,0x37,0x0D,0x27,0x26,0x20,0x29,0x04,0x21,0x24,0x11,0x2D,0x2E,0x1F, 0x2C,0x1E,0x39,0x33,0x07,0x2A,0x28,0x1D,0x0A,0x2E,0x32,0x38,0x13,0x2B,0x3F,0x0C }; const unsigned char PaletteLUT_2C04_0004 [64] ={ 0x18,0x03,0x1C,0x28,0x2E,0x35,0x01,0x17,0x10,0x1F,0x2A,0x0E,0x36,0x37,0x0B,0x39, 0x25,0x1E,0x12,0x34,0x2E,0x1D,0x06,0x26,0x3E,0x1B,0x22,0x19,0x04,0x2E,0x3A,0x21, 0x05,0x0A,0x07,0x02,0x13,0x14,0x00,0x15,0x0C,0x3D,0x11,0x0F,0x0D,0x38,0x2D,0x24, 0x33,0x20,0x08,0x16,0x3F,0x2B,0x20,0x3C,0x2E,0x27,0x23,0x31,0x29,0x32,0x2C,0x09 };
Backdrop color (palette index 0) uses
During forced blanking, when neither background nor sprites are enabled in PPUMASK ($2001), the picture will show the backdrop color. If only the background or sprites are disabled, or if the left 8 pixels are clipped off, the PPU continues its normal video memory access pattern but uses the backdrop color for anything disabled.
The background palette hack
During forced blanking, if the current VRAM address ever points to a palette register (i.e., $3F00-$3FFF), then the color in that palette register will be output to the screen instead of the backdrop color, for as long as the VRAM address is pointing there during the forced blanking. This can be used to display colors from the normally unused $3F04/$3F08/$3F0C palette locations. (Looking at the relevant circuitry in Visual 2C02, this happens because the palette RAM's output is not disconnected from the video output circuitry when not rendering.)
A loop that fills the palette will cause each color in turn to be shown on the screen, so to avoid rainbow artifacts while loading the palette, wait for a real vertical blank first using an NMI technique.
Color names
When programmers and artists are communicating, it's often useful to have human-readable names for colors. Many graphic designers who have done web or game work will be familiar with HTML color names.
Luma
- $0F: Black
- $00: Dark gray
- $10: Light gray or silver
- $20: White
- $01-$0C: Dark colors, medium mixed with black
- $11-$1C: Medium colors, similar brightness to dark gray
- $21-$2C: Light colors, similar brightness to light gray
- $31-$3C: Pale colors, light mixed with white
Chroma
Names for hues:
- $x0: Gray
- $x1: Azure
- $x2: Blue
- $x3: Violet
- $x4: Magenta
- $x5: Rose
- $x6: Red or maroon
- $x7: Orange
- $x8: Yellow or olive
- $x9: Chartreuse
- $xA: Green
- $xB: Spring
- $xC: Cyan
RGBI
These NES colors approximate colors in 16-color RGBI palettes, such as the CGA, EGA, or classic Windows palette, though the NES doesn't really have particularly good approximations:
- $0F: 0/Black
- $02: 1/Navy
- $1A: 2/Green
- $1C: 3/Teal
- $06: 4/Maroon
- $14: 5/Purple
- $18: 6/Olive ($17 for the brown in CGA/EGA in RGB)
- $10: 7/Silver
- $00: 8/Gray
- $12: 9/Blue
- $2A: 10/Lime
- $2C: 11/Aqua/Cyan
- $16: 12/Red
- $24: 13/Fuchsia/Magenta
- $28: 14/Yellow
- $30: 15/White
See also
- NTSC video - details of the NTSC signal generation and how it produces the palette
- PAL video
- Palettes (gallery) - a few different visualizations of PPU palettes.
- Another palette test - Simple test ROM to display the palette.
- Full palette demo - Demo that displays the entire palette with all emphasis settings at once.
- RGB PPU Palette Converter - RGB PPU palette conversion and visualization tool, written by WhoaMan.
References
- Re: Various questions about the color palette and emulators - 2012 collection of 2C03, 2C04, 2C05 palettes.