Specifications

96 Issue Date: 2004/11/05 │ CONFIDENTIAL
CL765 │ Camera Application Processor
Datasheet │ Doc. #: CLQP-DS-743
4.18. DATA FORMAT
The CL765 supports JPEG and Raw data formats, but the use of JPEG format is
recommended to minimize the image file size.
Raw data format is useful when a carrier or handset maker provides the special
processing of the captured image. In this case, the image is configured in YCbCr
4:2:2 format. When supporting Raw data format, the CL765 receives captured
images from the sensor and stores them in its internal buffer in the order of
receipt, and modem CPU can read one pixel at a time.
Since it is stored in 4:2:2 format, 4:4:4 format can be created by reading two pixels
each time. The order of data entering is as follows.
Odd sequences: CbY1
Even sequences: CrY2
The CL765 supports only the baseline sequential, the most popular mode among
JPEG modes. JPEG image format basically follows (complies with) JFIF 1.02
format, and it consists of the following.
SOI(Start Of Image) marker (0xFFD8)
JPEG File Header: (JFIF 1.02)
JPEG bit-stream
EOI(End Of Image) marker (0xFFD9)
JPEG file header complies with JFIF(JPEG File Interchange Format) 1.02, and it
takes about 600~700byte to describe it all, which is not small. In case of 128x96-
sized image, it takes up roughly 1/3 ~ 1/2, so expressing it in shortened format is
possible, if needed. There are four types of format for this part.
Perfect (full) file header format: Records all information to make it
ubiquitously compatible.
Shortened format: Omitting the fixed parts such as Huffman table and
image sizes, express only the variable markers.
Peculiar format: Separate from JPEG file format, the format that expresses
the information in about 4bytes. The header has been reduced to the high
degree.
JPEG header-only
Standard markers used in JPEG are as follows. JPEG file header starts with SOI
(0xffd8), followed by the marker that includes the information of the image that
has been compressed with JPEG bit stream. the CL765 supports the following
markers.
SOF0 (0xffc0)
DHT (0xffc4)
SOI (0xffd8)
EOI (0xffd9)