File talk:ZX Spectrum standard palette with 8x8 dithering.png

Dim / bright

The brightness of the real ZX Spectrum hardwares connected to a CRT TV set in the early 1980s is quite difficult to grasp on today's systems and displays. While the conversion of the 7 colors in BRIGHT 1 looks pretty straightforward, the counterpart in BRIGHT 0 seems still questionable: dim values mapped to 192 (even less in my recollections) or 205 (at least)¹ in 24-bit RGB.

→ The following Sinclair BASIC code (.tap cassette available here) may remind us of the actual dim / bright balance:

1 READ u$,v$,w$,x$,e$,y$,r$,t$,m$,k$,i$,o$,g$: DIM f$(2,4): READ f$(1),f$(2): LET p=23693: FOR n=0 TO 7: READ c,a,a$: LET z$=f$(INT (n/4)+1)+g$: LET s$=a$+i$+z$: LET s=32-LEN s$: BORDER c: POKE p-69,a: POKE p,a: CLS : PRINT TAB s;s$;#1;TAB s;a$;o$;z$: PRINT AT 11,0;u$'w$: PRINT BRIGHT 0; PAPER c; INK 9;AT 11,22;v$;AT 12,22;x$: PAUSE 0: NEXT n: DATA "ZX SPECTRUM: PALETTE:","DIM/BRIGHT","ON THE REAL HARDWARE:","EYESTRAIN?","-LIKE","INVISIBLY ","TOO ","BRIGHT","DIM","DARKISH "," SCREEN "," BORDER ","GROUND","FORE","BACK",2,71,r$+t$,3,7,r$+m$,3,68,k$+t$,2,1,y$+m$,2,120,r$+t$,2,56,r$+m$,3,104,m$+e$,4,112,t$+e$: REM Eyestrain?.tap v1.0: dpla's reminder on 2021-09-02.

--Dpla-fr (talk) 07:04, 2 September 2021 (UTC)

¹: 4throck stopped at 224 in the main article (after 'trying' 238 on the dithering chart). My code above is a personal evidence on the related and genuine hardwares in PAL (I used them during at least a handful of years, in France and abroad since the early 1980s). By establishing that his demonstration does not work well with 205 and higher, I'd advocate for the more reliable 192 in my current estimation or viewpoint. Besides, thousands of Speccy users may need to know where these almost unusable and faulty-looking 'dim' values come from (beyond the brief explanation of a « PAL gamma approximation »), suddenly. --Dpla-fr (talk) 00:21, 13 September 2021 (UTC) P.S. This related discussion.--Dpla-fr (talk) 02:21, 13 September 2021 (UTC)