— Full 'spectrum' employing prepared 8×8 cells. —

= 15 plain colors shown as full rows
+ 64 dithers per all possible blendings, where the inverted patterns were discarded. The type or look of the patterns is unimportant; what counts is the 1-bit ratio in each 8×8 cell.

BRIGHTNESS / CONTRAST
The accuracy of the dim colors is still questionable, in particular they show these great variations after conversion:

• 205 in the 3 RGB components seems to be widespread (Spectaculator emulates more or less this way);
• 192 values were seen on e.g. Wikipedia since 2007-01-08 (Fuse did not change its palette emulation);
• 224 since 2021-07-23 from an undefined « PAL gamma approximation » (238 temporarily in 4throck's trial).

CODES

• Image doable as 6 split screens on the native 256×192-pixel systems, e.g. with a redefined charset and scrollings;
  

• Alternate chart in ZX Spectrum BASIC (.tap cassette available here):
  

9999: BORDER 0: PAPER 0: CLEAR USR "a"-512: LET u=23606: LET b=u+18: LET s=b+69: POKE b,70: POKE s,70: LET a=USR "a"-511: LET c=a-392: LET a$="CgGc1U5Q3W7SAeEaLpPl:^>Z<£@\JnNjDhHd2V6R4X8TBfFbKoOk9]=Y;_?[ImMi": DIM b$(64): FOR n=1 TO 32: LET b$(n)=CHR$ (n+48): LET b$(65-n)=CHR$ (80+n): NEXT n: POKE b,22: PRINT #1;AT 0,0;"  BUSY  ": OVER 1: FOR n=1 TO 64: PLOT CODE a$(n)-49,0: FOR f=0 TO 7: POKE a+(n-1)*8+f,PEEK (22432+f): NEXT f: NEXT n: POKE b,64: CLS : POKE s,56: PRINT AT 0,9;" ZX SPECTRUM ": POKE s,198: PRINT AT 1,9;" PRESS A KEY ": POKE s,7: PRINT AT 3,3;"15-color standard palette:": BRIGHT 1: FOR n=1 TO 7: PRINT PAPER 8-n,, BRIGHT 0,,: NEXT n: PRINT ''TAB 2; INK 6;"3,584 8x8 ordered dithers...": POKE u,c-256*INT (c/256): POKE u+1,INT (c/256): FOR l=0 TO 2: FOR p=7 TO 0 STEP -1: FOR i=0 TO p: POKE s-1,1: PRINT INK i; PAPER p;b$ AND i<>p; BRIGHT 0;b$ AND i<>p;: NEXT i: NEXT p: NEXT l: POKE u,0: POKE u+1,60: POKE b,71: POKE s,71: REM 3543Colors.tap v1.0 by dpla on 2021-09-12.

COUNTS

• 3543 unique dithers (Speccy-colored 8×8-pixel cells in 1 bpp):

15[*1]+(1+2+3+4+5+6+7)[*2]×63[*3]×2[*4] = 15+28×63×2 pseudocolors [*1: plain colors; *2: blendings; *3: dithered cells; *4: brightness levels];

• 3399 unique colors once blended (144 duplicates discarded in 24 bpp).