The opposite of function 0Ch: it returns in AL the colour of the pixel at column CX, row DX of page BH, decoding the mode's memory layout. In the 16-colour EGA and VGA modes that means reading all four bit planes and putting the bits together, which is awkward to do by hand.

Typical uses are flood fill, collision tests in simple games ("is the pixel ahead not black?") and saving a small area before drawing over it. Like 0Ch it costs one interrupt per pixel. Here a pixel is drawn and read back, together with its untouched neighbour:

Prints "pixel 10,10 = 0Eh, pixel 11,10 = 00h"; on the screen a single yellow dot near the top left for 2 seconds, then the text screen comes back cleared.
MOV     AX, 0013h  ; 320x200, 256 colours: all pixels 0
INT     10h
MOV     AX, 0C0Eh  ; write a pixel, colour 0Eh (yellow)
MOV     BH, 0
MOV     CX, 10     ; x
MOV     DX, 10     ; y
INT     10h
MOV     AH, 0Dh    ; read it back
MOV     BH, 0
MOV     CX, 10
MOV     DX, 10
INT     10h        ; AL = its colour
MOV     [PIX1], AL
MOV     AH, 0Dh    ; and its neighbour, never drawn
MOV     BH, 0
MOV     CX, 11
MOV     DX, 10
INT     10h
MOV     [PIX2], AL
MOV     CX, 001Eh  ; wait 2 s: CX:DX = 1E8480h microseconds
MOV     DX, 8480h
MOV     AH, 86h    ; BIOS: wait
INT     15h
MOV     AX, 0003h  ; mode 03h again: 80x25 text, clears the screen
INT     10h
MOV     AH, 09h
MOV     DX, OFFSET TXT1
INT     21h
MOV     AL, [PIX1]
CALL    PHEX2
MOV     AH, 09h
MOV     DX, OFFSET TXT2
INT     21h
MOV     AL, [PIX2]
CALL    PHEX2
MOV     AH, 09h
MOV     DX, OFFSET TXT3
INT     21h
 
PIX1    DB      0
PIX2    DB      0
TXT1    DB      "pixel 10,10 = $"
TXT2    DB      "h, pixel 11,10 = $"
TXT3    DB      "h", 13, 10, "$"
PHEX2:             ; print AL as two hex digits; changes AX, CX, DX
PUSH    AX
MOV     CL, 4
SHR     AL, CL     ; the high nibble first
CALL    PDIG1
POP     AX
AND     AL, 0Fh    ; then the low one, falling into PDIG1
PDIG1:
ADD     AL, "0"
CMP     AL, "9"
JBE     PDIG2
ADD     AL, 7      ; "A".."F"
PDIG2:
MOV     DL, AL
MOV     AH, 02h    ; DOS: print DL
INT     21h
RET

Pitfalls

In text modes the result means nothing. In the CGA modes some BIOSes return the colour with the XOR bit or other high bits undefined, so AND AL, 3 (or AND AL, 0Fh in 16-colour modes) is a safe habit. To read a whole area, go to video memory: in mode 13h a byte per pixel; in the planar modes select each plane in turn with the graphics controller's Read Map Select register (index 4 at port 3CEh) and read it.