shr al, 1
setc dh
shr al, 1
setc dl
shr al, 1
setc ch
shr al, 1
setc cl
shr al, 1
setc bh
shr al, 1
setc bl
shr al, 1
setc ah    

; input in AL

        movzx   edx,al
        shr     edx,4
        and     eax,0Fh

        mov     ecx,204081h
        mov     ebx,01010101h

        imul    eax,ecx
        and     eax,ebx

        imul    edx,ecx
        and     edx,ebx

; output in EDX:EAX    

; 8-byte data at ESI (assume DS=ES), input byte in DL:
        mov     edi,esi
        mov     ecx,8
@@:
        lodsb
        shr     al,1
        shr     dl,1
        rcl     al,1
        stosb
        loop    @b    

; input al = byte, output edx:eax
movzx eax, al
mov edx, 0x00204081
ror eax, 4
mov ecx, 0x01010101
mul edx
shld edx, eax, 4
and edx, ecx
and eax, ecx    

read 32MB pic to [m1]
read 4MB data to [m0]
[esi]=[m0]
[edi]=[m1]
mov al, [edi]
...
mov dh,[edi+7]
push eax
mov al,[esi];databyte
cmp al,00h
je La00
cmp al,01h
je La01
....
cmp al,0ffh
je Laff

La00:
pop eax
and al,0feh
...
and dh,0feh; if al=00h, 8Byte least significant bit will be 0,0,0,0,0,0,0,0
jmp Lawm

La01:
....;if al=01h, 8Byte least significant bit will be 0,0,0,0,0,0,0,1

Laff:
...; if  al=0ffh, 8Byte least significant bit will be 1,1,1,1,1,1,1,1

Lawm: ;write to mem
mov [edi],al
mov [edi+1],ah
...
mov [edi+7],dh
write out from [m1] to outfile

Every 8 picture Byte contains 1 secondary dataByte(8 least significant bit) 32MB pic,4MB secondary data.