Paul Burke's TIFF example

basic structure

The basic structure of a TIFF file is as follows:
The first 8 bytes forms the header. The first two bytes of which is either "II" for little endian byte ordering or "MM" for big endian byte ordering. In what follows we'll be assuming little endian ordering. Note: any true TIFF reading software is supposed to be handle both types. The next two bytes of the header should be 0 and 42dec (2ahex). The remaining 4 bytes of the header is the offset from the start of the file to the first "Image File Directory" (IFD), this normally follows the image data it applies to. In the example below there is only one image and one IFD.
An IFD consists of two bytes indicating the number of entries followed by the entries themselves. The IFD is terminated with 4 byte offset to the next IFD or 0 if there are none. A TIFF file must contain at least one IFD!
Each IFD entry consists of 12 bytes. The first two bytes identifies the tag type (as in Tagged Image File Format). The next two bytes are the field type (byte, ASCII, short int, long int, ...). The next four bytes indicate the number of values. The last four bytes is either the value itself or an offset to the values. Considering the first IFD entry from the example gievn below: 
   0100 0003 0000 0001 0064 0000
      |        |    |         |
tag --+        |    |         |
short int -----+    |         |
one value ----------+         |
value of 100 -----------------+

Example

The following is an example using the TIFF file shown on the right, namely a black image with a single white pixel at the top left and the bottom right position. The image is 100 pixels wide by 200 pixels high.
A hex dump is given below along with matching pointers and locations marked in matching colours, these colours further match the appropriate parts of the source code gievn later. The tags are underlined. 
   4d4d 002a 0000 ea68 ffff ff00 0000 0000
   0000 0000 0000 0000 0000 0000 0000 0000

   .... ....  black 0's deleted  .... ....

   0000 0000 00ff ffff 000e 0100 0003 0000
   0001 0064 0000 0101 0003 0000 0001 00c8
   0000 0102 0003 0000 0003 0000 eb16 0103
   0003 0000 0001 0001 0000 0106 0003 0000
   0001 0002 0000 0111 0004 0000 0001 0000
   0008 0112 0003 0000 0001 0001 0000 0115
   0003 0000 0001 0003 0000 0116 0003 0000
   0001 00c8 0000 0117 0004 0000 0001 0000
   ea60 0118 0003 0000 0003 0000 eb1c 0119
   0003 0000 0003 0000 eb22 011c 0003 0000
   0001 0001 0000 0153 0003 0000 0003 0000
   eb28 0000 0000 0008 0008 0008 0000 0000
   0000 00ff 00ff 00ff 0001 0001 0001
Example image

The above example uses 14dec (000eihex) directory entries.
0100 - Image width
0101 - Image height
0102 - Bits per sample (8)
0103 - Compression method (1 = uncompressed)
0106 - Photometric Interpretation (2 = RGB)
0111 - Strip Offsets
0112 - Orientation (1 = 0 top, 0 left hand side) 0115 - Samples per pixel (1)
0116 - Rows per strip (200 = image height)
0117 - Strip Byte Counts (60000 = 100 x 200 x 3)
0118 - Minimum sample value (0,0,0)
0119 - Maximum sample value (255,255,255)
011c - Planar configuration (1 = single image plane)
0153 - Sample format

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