Editing PNG (section)

=== Examples ===
{| class="wikitable" style="text-align: center;"
|+ Structure of a very simple PNG file
|-
| style="width: 20em"| {{code|89 50 4E 47 0D 0A 1A 0A}}<br />PNG signature
| style="width: 14em"| {{code|IHDR}}<br />Image header
| style="width: 26em"| {{code|IDAT}}<br />Image data
| style="width: 14em"| {{code|IEND}}<br />Image end
|}

{| class="wikitable"
|+ Contents of a minimal PNG file representing one red pixel
|-
! scope="col"|Hex
! scope="col"|As characters
|-
| style="font-family: Consolas, Andale Mono, Courier New, monospace"|
<span style="background:#fcc;">89 50 4E 47 0D 0A 1A 0A</span> <span style="background:#cfc;">00 00 00 0D 49 48 44 52</span><br />
<span style="background:#cfc;">00 00 00 01 00 00 00 01 08 02 00 00 00 90 77 53</span><br />
<span style="background:#cfc;">DE</span> <span style="background:#ccf;">00 00 00 0C 49 44 41 54 08 D7 63 F8 CF C0 00</span><br />
<span style="background:#ccf;">00 03 01 01 00 18 DD 8D B0</span> <span style="background:#fec;">00 00 00 00 49 45 4E</span><br />
<span style="background:#fec;">44 AE 42 60 82</span>
| style="font-family: Consolas, Andale Mono, Courier New, monospace"|
<span style="background:#fcc;">.PNG....</span><span style="background:#cfc;">....IHDR</span><br />
<span style="background:#cfc;">..............wS</span><br />
<span style="background:#cfc;">.</span><span style="background:#ccf;">....IDAT..c....</span><br />
<span style="background:#ccf;">.........</span><span style="background:#fec;">....IEN</span><br />
<span style="background:#fec;">D.B`.</span>
|}
{| class="wikitable"
|+IHDR Chunk
!Offset into chunk
!Hex Value
!Decimal Value
!Text
!Meaning
|-
|0
|0x0D
|13
|
|IHDR chunk has 13 bytes of content
|-
|4
|0x49484452
|
|IHDR
|Identifies a Header chunk
|-
|8
|0x01
|1
|
|Image is 1 pixel wide
|-
|12
|0x01
|1
|
|Image is 1 pixel high
|-
|16
|0x08
|8
|
|8 bits per pixel (per channel)
|-
|17
|0x02
|2
|
|Color type 2 (RGB/truecolor)
|-
|18
|0x00
|0
|
|Compression method 0 (only accepted value)
|-
|19
|0x00
|0
|
|Filter method 0 (only accepted value)
|-
|20
|0x00
|0
|
|Not interlaced
|-
|21
|0x907753DE
|
|
|CRC of chunk's type and content (but not length)
|}
{| class="wikitable"
|+IDAT Chunk
!Offset  into chunk
!Hex Value
!Meaning
|-
|0
|0x0C
|IDAT chunk has  12 bytes of content
|-
|4
|0x49444154
|Identifies a Data chunk
|-
|8
|0x08
|DEFLATE compression method using a 256-byte window{{ref RFC|1950}}
|-
|9
|0xD7
|ZLIB FCHECK value, no dictionary used, maximum compression algorithm<ref name="rfc1950" />
|-
|10
|0x63F8CFC00000
|A compressed DEFLATE block using the static Huffman code that decodes to 0x00 0xFF 0x00 0x00{{ref RFC|1951}}
|-
|16
|0x03010100
|The ZLIB check value: the [[Adler-32]] checksum of the uncompressed data<ref name="rfc1950" />
|-
|20
|0x18DD8DB0
|CRC of chunk's type and content (but not length)
|}
Displayed in the fashion of [[hex editor]]s, with on the left side byte values shown in [[Hexadecimal|hex format]], and on the right side their equivalent characters from [[ISO-8859-1]] with unrecognized and control characters replaced with periods. Additionally the PNG signature and individual chunks are marked with colors. Note they are easy to identify because of their human readable type names (in this example PNG, IHDR, IDAT, and IEND).