>Hi folks!
>Using GDIPlusX, how to remove all non black pixels from an image?


If you capture the data to a 32-bit bitmap, you can read the bitmap buffer data and look for all CHR(0)+CHR(0)+CHR(0) combinations at either the start or end of the 4-byte block (depending on endian, a small test would indicate which it is) references which occur on 4-byte boundaries:

lcBlack = CHR(0)+CHR(0)+CHR(0)
FOR lnI = 1 TO bufferLength STEP 4
    IF SUBSTR(buffer, lnI, 3) == lcBlack OR SUBSTR(buffer, lnI + 1, 3) == lcBlack
        * It's a black pixel
    ENDIF
NEXT

You could also capture the bitmap, invert its colors, use VFP to overlay the inverted image atop a known background color with the Image's mode set to TRANSPARENT (where all WHITE pixels are ignored), then capture that image and save it to another buffer. Then, repeat the same process using another background color. In such a case, every difference between the two images will be where the black pixels were.