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Comment on ASCII characters are not pixels: a deep dive into ASCII rendering

This guy built an image-to-ASCII renderer.

This is so impressive!!!

Mesmerizing…

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I made one myself many years ago for DOS, but mine renders in 512 pseudo halftone colors from a base palette of 16 colors. Results look pretty nice for whatever it’s worth, but yeah mine doesn’t focus on their efforts to get more crisp edges.

Still neat though, food for my thoughts even, should I ever revisit my old project.

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Alb@sh.itjust.works ⁨1⁩ ⁨day⁩ ago
Yes you should, this would be awesome with a special focus on the crisp edges!

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- over_clox@lemmy.world ⁨1⁩ ⁨day⁩ ago
  I’m not exactly sure how I’d incorporate both techniques into the same rendering system though.
  
  My method doesn’t use letters, numbers or punctuation characters, mine uses the DOS mode block characters, blank space, 25%, 50%, 75% halftone characters, and the 100% solid block character.
  
  I could probably get a little closer with my method if I add in the upper half block and lower half block characters, but when using those characters I’m no longer able to use the halftone dithering and would be limited to 8 background and 16 foreground colors…
  
  I dunno where I’d really even start (over) again to use alphanumeric characters with my text rendering method…
  
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  - Alb@sh.itjust.works ⁨1⁩ ⁨day⁩ ago
    Maybe converting the DOS blocks to ANSI blocks. But i don’t know if this is feasible with your coding…
    
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kora@sh.itjust.works ⁨1⁩ ⁨day⁩ ago

Would love to see your implementation. Have you considered making it public?

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over_clox@lemmy.world ⁨1⁩ ⁨day⁩ ago

Sure, have at it!

Sorry it’s not a full complete dump with examples, but it’s programmed in QBasic 1.1 and converts raw RGB pixel data into equivalent closest matching color halftone onscreen characters. I designed it in mind with DOS text modes of either 80x25, 80x43, or 80x50 text modes, but I’m sure the technique can work with any text mode that can properly render the old DOS block characters. But, I’m betting that whatever device you’re using right now is almost certainly not configured to display the old DOS block characters as they were back in the day.

Good luck!

REM TEXTPSET.BAS
REM over_clox - February 26, 2008

DECLARE SUB DisplayRAW (FileName$, W%, H%)
DECLARE SUB TextPSet (X%, Y%, R%, G%, B%)
DECLARE SUB TextPixel (Red%, Green%, Blue%, Char$, FGround%, BGround%)
DECLARE SUB HTMtoRGB (HTMColor$, Red%, Green%, Blue%)

TYPE PaletteType
    R AS INTEGER
    G AS INTEGER
    B AS INTEGER
END TYPE

REDIM SHARED DOSPalette(15) AS PaletteType
REDIM SHARED FakePalette(15, 7, 1 TO 3) AS PaletteType

RESTORE
FOR I% = 0 TO 15
    READ HTMColor$
    HTMtoRGB HTMColor$, R%, G%, B%
    DOSPalette(I%).R = R%
    DOSPalette(I%).G = G%
    DOSPalette(I%).B = B%
NEXT

FOR C% = 1 TO 3
    C2% = 4 - C%
    FOR B% = 0 TO 7
        FOR F% = 0 TO 15
            R1% = DOSPalette(F%).R: R2% = DOSPalette(B%).R
            G1% = DOSPalette(F%).G: G2% = DOSPalette(B%).G
            B1% = DOSPalette(F%).B: B2% = DOSPalette(B%).B
            FakePalette(F%, B%, C%).R = (R1% * C% + R2% * C2%) \ 4
            FakePalette(F%, B%, C%).G = (G1% * C% + G2% * C2%) \ 4
            FakePalette(F%, B%, C%).B = (B1% * C% + B2% * C2%) \ 4
        NEXT
    NEXT
NEXT

'MS-DOS Text Mode 16 Color Palette
DATA 000000,0000AA,00AA00,00AAAA,AA0000,AA00AA,AA5500,AAAAAA
DATA 555555,5555FF,55FF55,55FFFF,FF5555,FF55FF,FFFF55,FFFFFF

CMD$ = COMMAND$
IF CMD$ <> "" THEN
    DisplayRAW CMD$, 80, 25
ELSE
    DisplayRAW "LOGO.RAW", 80, 25
END IF

'DEF SEG = &HB800: BSAVE "LOGO.BSV", 0, 4000

COLOR 7, 0

DO: Hit$ = UCASE$(INKEY$): LOOP WHILE Hit$ = ""

SUB DisplayRAW (FileName$, W%, H%)

    FileNum% = FREEFILE
    OPEN FileName$ FOR BINARY AS FileNum%
    CLS : WIDTH W%, H%
    ScanLine$ = SPACE$(W% * 3)
    FOR Y% = 0 TO H% - 1
        GET #1, , ScanLine$
        FOR X% = 0 TO W% - 1
            R% = ASC(MID$(ScanLine$, X% * 3 + 1, 1))
            G% = ASC(MID$(ScanLine$, X% * 3 + 2, 1))
            B% = ASC(MID$(ScanLine$, X% * 3 + 3, 1))
            TextPSet X%, Y%, R%, G%, B%
        NEXT
    NEXT
    CLOSE FileNum%

END SUB

SUB HTMtoRGB (HTMColor$, Red%, Green%, Blue%)
    Red% = VAL("&H" + MID$(HTMColor$, 1, 2))
    Green% = VAL("&H" + MID$(HTMColor$, 3, 2))
    Blue% = VAL("&H" + MID$(HTMColor$, 5, 2))
END SUB

SUB TextPixel (Red%, Green%, Blue%, Char$, FGround%, BGround%)
    ' °±²Û (32,176,177,178,219)
   
    Diff% = 768: BGround% = 0
    FOR F% = 0 TO 15
        RDiff% = ABS(DOSPalette(F%).R - Red%)
        GDiff% = ABS(DOSPalette(F%).G - Green%)
        BDiff% = ABS(DOSPalette(F%).B - Blue%)
        NewDiff% = RDiff% + GDiff% + BDiff%
        IF NewDiff% < Diff% THEN
            Diff% = NewDiff%: Char$ = "Û": FGround% = F%
        END IF
    NEXT

    FOR C% = 1 TO 3
        C2% = 4 - C%
        FOR B% = 0 TO 7
            FOR F% = 0 TO 15
                RDiff% = ABS(FakePalette(F%, B%, C%).R - Red%)
                GDiff% = ABS(FakePalette(F%, B%, C%).G - Green%)
                BDiff% = ABS(FakePalette(F%, B%, C%).B - Blue%)
                NewDiff% = RDiff% + GDiff% + BDiff%
                IF NewDiff% < Diff% THEN
                    Diff% = NewDiff%: Char$ = CHR$(175 + C%)
                    FGround% = F%: BGround% = B%
                END IF
            NEXT
        NEXT
    NEXT

END SUB

SUB TextPSet (X%, Y%, Red%, Green%, Blue%)
    TextPixel Red%, Green%, Blue%, Char$, FGround%, BGround%
    LOCATE Y% + 1, X% + 1: COLOR FGround%, BGround%: PRINT Char$;
END SUB

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kora@sh.itjust.works ⁨1⁩ ⁨day⁩ ago
You are amazing. Thank you very much for delivering! Half of the fun is discovering how it works without examples so no need to apologise :^)

I need to look into running QBasic on my M4. Unsure about my options for now. Worst case scenario I spin up a VM tomorrow.

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