Some PNG related stuff

blah.txt

00000000  89 50 4e 47 0d 0a 1a 0a  00 00 00 0d 49 48 44 52  |.PNG........IHDR|
00000010  00 00 00 01 00 00 00 01  08 06 00 00 00 1f 15 c4  |................|
00000020  89 00 00 00 0d 49 44 41  54 78 da 63 98 f5 f9 7b  |.....IDATx.c...{|
00000030  34 00 07 8f 02 e0 a7 82  a8 9a 00 00 00 00 49 45  |4.............IE|
00000040  4e 44 ae 42 60 82                                 |ND.B`.|
00000046

89 50 4e 47 0d 0a 1a 0a    - magic

Chunk:
  00 00 00 0d     - size (13)
  49 48 44 52     - type 'IHDR'
    00 00 00 01     - width (1)
    00 00 00 01     - height (1)
    08              - bit depth (8)
    06              - colour type (6, RGBA)
    00              - compression method (0, DEFLATE)
    00              - filter method (0, NONE)
    00              - interlace method (0, NONE)
  1f 15 c4 89     - CRC

Chunk:
  00 00 00 0d      - size (13)
  49 44 41 54      - type (IDAT)
    78 da 63 98 f5 f9 7b 34 00 07 8f 02 e0    - DEFLATE stream
  a7 82 a8 9a      - CRC

Chunk:
  00 00 00 00      - size (0)
  49 45 4e 44      - type (IEND)
  (no payload)
  ae 42 60 82      - CRC


DEFLATE stream:

    78     - compression method (8, DEFLATE), flags (7, 32K LZ77 window)
    da     - flags 110 11010 fcheck (0b11010), dict (0), flevel (3, max compression)
    63 98 f5 f9 7b 34 00    - compressed data
    07 8f 02 e0   - ADLER32 checksum

Result of decompressing:
  
irb(main):006:0> x = ['78da6398f5f97b3400078f02e0'].pack('H*')
=> "x\xDAc\x98\xF5\xF9{4\x00\a\x8F\x02\xE0"
irb(main):007:0> Zlib::Inflate.inflate(x)