test.bas

' Load the image
imageHandle = _LOADIMAGE("path/to/image.png")

' Define the EGA palette (example with 4 colors for simplicity)
DIM egaPalette(3) AS _UNSIGNED LONG
egaPalette(0) = _RGB(0, 0, 0)       ' Black
egaPalette(1) = _RGB(0, 0, 170)     ' Blue
egaPalette(2) = _RGB(0, 170, 0)     ' Green
egaPalette(3) = _RGB(0, 170, 170)   ' Cyan

' Function to find the closest color in the palette
FUNCTION FindClosestColor (color AS _UNSIGNED LONG)
    DIM minDistance AS DOUBLE
    DIM closestColor AS _UNSIGNED LONG
    minDistance = 1E+30 ' Initialize with a large number

    FOR i = 0 TO UBOUND(egaPalette)
        distance = ColorDistance(color, egaPalette(i))
        IF distance < minDistance THEN
            minDistance = distance
            closestColor = egaPalette(i)
        END IF
    NEXT i

    FindClosestColor = closestColor
END FUNCTION

' Function to calculate the distance between two colors
FUNCTION ColorDistance (color1 AS _UNSIGNED LONG, color2 AS _UNSIGNED LONG)
    r1 = _RED(color1)
    g1 = _GREEN(color1)
    b1 = _BLUE(color1)
    r2 = _RED(color2)
    g2 = _GREEN(color2)
    b2 = _BLUE(color2)
    ColorDistance = SQR((r2 - r1) ^ 2 + (g2 - g1) ^ 2 + (b2 - b1) ^ 2)
END FUNCTION

' Create a new image with the palette colors
newImageHandle = _NEWIMAGE(_WIDTH(imageHandle), _HEIGHT(imageHandle), 32)
FOR y = 0 TO _HEIGHT(imageHandle) - 1
    FOR x = 0 TO _WIDTH(imageHandle) - 1
        originalColor = POINT(x, y, imageHandle)
        newColor = FindClosestColor(originalColor)
        PSET (x, y), newColor, newImageHandle
    NEXT x
NEXT y

' Display the new image
SCREEN _NEWIMAGE(_WIDTH(imageHandle), _HEIGHT(imageHandle), 32)
_PUTIMAGE (0, 0), newImageHandle