Truevision TGA, File Format Specification, Version 2.0 as - DCA

Raw Packet (i.e., Non-Run-Length Encoded):
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The raw packet is always composed of two fields. The first field is the Repetition Count and the second
fieldisthePixelDatafield.
Table 4 - Raw Packet
1. Pixel Count: The pixel count can range from 0 to 127. Since a raw packet never encodes zero
pixels, and in order to make use of all of the values available with seven bits, a zero (0) in Pixel Count is
defined to mean that 1 pixel is included in the packet. A 1 in Pixel Count means that 2 pixels are actually
contained in the packet. In other words, the value in Pixel Count is always 1 less than the actual number of
pixels contained in the packet. Thus, you may encode between 1 and 128 pixels with a single packet. If
you have a run which is longer than 128 bytes, you must encode it using multiple packets.
Note: The high-order bit of this subfield is always set to 0 to indicate that the packet type is a Raw Packet.
2. Pixel Data: Non-Run-Length Encoded pixel data. The pixels will be displayed in the order that
they are stored.