TC5747 Datasheet, PDF (15/44 Pages) List of Unclassifed Manufacturers – Single Chip CMOS Imager with Integrated Image Signal Processor and JPEG Codec

TC5747 Preliminary Data Sheet
Single Chip CMOS Imager
TransChip supplies sample C code, which shows how to upload the firmware and use the host commands
(software API). The sample includes all the needed C header files. The supplied firmware comes with preset
default values for the various controls. Thus even if no single host commands is performed the firmware
ensures that the sensor is running properly according to a preset default set.
TransChip also supplies a released version of the firmware.
The host commands are fully detailed in a separate document.
2.13 Bayer to YUV Translation Unit (YUVR)
The YUVR is the color-processing unit. The unit’s parameters and mode registers are loaded through the
control bus. The Bayer image is received from the IMGA unit, processed by the YUVR unit, and transferred to
the PVI unit for output out of the device. While processing the image, statistics are calculated by the YUVR
unit. After completing the processing of an image, the YUVR unit produces an interrupt to the CONT unit. The
YUVR thus signifies to the CONT that the statistics for the current image are ready, and the CONT may read
the results through the main control bus.
The YUVR unit receives the Bayer grid as input. For each pixel, two color values are missing and need to be
reconstructed. The input accuracy is 10 bits. The YUVR unit reconstructs the RGB per pixel, performs
correction algorithms and generates the YUV representation of the image.
Digital color processing includes: demosaicing, dynamic range enhancement, digital gain, filter
downscaling, sharpening or blurring, flicker detection and removal, color and white balance correction,
gamma correction, color suppression, zoom by 2X or 4X, RGB to YUV conversion, YUV-to-RGB conversion,
down sample and cropping of RGB for display, RGB formatting (6:6:6, 5:6:5, 4:4:4) are all performed in the
YUVR unit.
Zoom is performed by creating a full resolution image from a small region in the center of the image. The
small region is blown up by 2X or by 4X to the target image size. The missing pixels are interpolated from
the original pixels using a filter to provide a smooth appearance.
2.14 JPEG Compression Unit (JCOR)
The JPEG unit receives the YUV 4:2:2 image data from the YUVR unit, and performs real-time JPEG
compression. A 25K Byte memory is used for the JPEG compression process. The memory is divided into a
Raster-to-Block operation buffer and a JPEG-code memory section. The 64K Bytes of memory can hold a
full VGA-sized compressed image at a compression ratio of up to 1.7 bits per pixel.
The partition of the memory is fully configurable.
When a higher compression ratio is used, several images can be stored in the memory. For example,
when capturing a VGA-sized image, three compressed images of 0.5 bits per pixel can be stored in the
64K Byte JPEG-code memory section.
When capturing a smaller image, a smaller buffer is required for the Raster-to-Block operation.
Therefore a larger JPEG-code memory section can be allocated for support of a lower compression
ratio.
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