Editing GIF (section)

===Image decoding===
Decoding begins by mapping the stored bytes back to 9-bit codes. These are decoded to recover the pixel colors as shown below. A table identical to the one used in the encoder is built by adding strings by this rule:
{| class="wikitable"
|+ Is incoming code found in table?
|  {{Yes}} || add string for local code followed by first byte of string for incoming code
|-
|  {{No}}  || add string for local code followed by copy of its own first byte
|}

       '''shift'''
 '''9-bit ----> Local      Table                 Pixel'''
 <u>'''code        code   code --> string   Palette color  Action'''</u>
 100h               000h  | #0                       Initialize root table of 9-bit codes
                     :    | palette
                     :    | colors
                    0FFh  | #255
                    100h  | clr
                    101h  | end
 028h                     |             #40   {{font color|WHITE|BLACK|BLACK}}  Decode 1st pixel
 0FFh        028h         |                           Incoming code found in table
                          |             #255  {{font color|BLACK|WHITE|WHITE}}   - output string from table
                    102h  | 28 FF                     - add to table
 103h        0FFh         |                           Incoming code not found in table
                    103h  | FF FF                     - add to table
                          |                           - output string from table
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
 102h        103h         |                           Incoming code found in table
                          |                           - output string from table
                          |             #40   {{font color|WHITE|BLACK|BLACK}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                    104h  | FF FF 28                  - add to table
 103h        102h         |                           Incoming code found in table
                          |                           - output string from table
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                    105h  | 28 FF FF                  - add to table
 106h        103h         |                           Incoming code not found in table
                    106h  | FF FF FF                  - add to table
                          |                           - output string from table
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
 107h        106h         |                           Incoming code not found in table
                    107h  | FF FF FF FF               - add to table
                          |                           - output string from table
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
                          |             #255  {{font color|BLACK|WHITE|WHITE}}
 101h                     |                           End