Image sensor data compression and DSP decompression
View Patent ↗An image sensor compresses image data prior to transmitting the image data to a DSP. The image sensor captures light representing an image, for instance via a camera's aperture. A focal plane array converts the captured light into pixel data. The pixel data is sorted into categories, and is compressed in parallel by a compression engine. The compressed pixel data is then sent to a DSP, which may be located off-chip. The DSP then decompresses the compressed pixel data, performs image signal processing operations on the compressed pixel data, and then compresses the processed pixel data into a digital image format. The image sensor may buffer the pixel data for one or more images to accommodate for slowdown by the compression engine. The pixel data may be sorted by row and column of a pixel array. Alternatively, the pixel data may be sorted by color from a Bayer color filter.
1. A method for decompressing image data, the method comprising:
receiving, from an image sensor chip, compressed pixel data, the compressed pixel data comprising pixel data organized into a plurality categories and compressed by the image sensor chip at a magnitude of compression selected based on a rate at which the pixel data is captured;
decompressing, by a digital signal processor (DSP), the compressed pixel data to produce decompressed pixel data organized into the plurality of categories;
combining the categories of decompressed pixel data to produce combined pixel data;
compressing the combined pixel data to produce a digital image comprising a digital image format; and
outputting the digital image.
2. The method of claim 1 , wherein each pixel of the decompressed pixel data is organized into a plurality of categories comprising a) either odd column pixel data or even column pixel data, and b) either odd row pixel data or even row pixel data.
3. The method of claim 2 , wherein combining the categories of decompressed pixel data comprises interleaving pixel data comprising odd column pixel data and pixel data comprising even column pixel data, and interleaving pixel data comprising odd row pixel data and pixel data comprising even row pixel data.
4. The method of claim 1 , wherein the decompressed pixel data is organized into a plurality of categories comprising red pixel data, blue pixel data, a first portion of green pixel data, and a second portion of green pixel data.
5. The method of claim 4 , wherein combining the categories of decompressed pixel data comprises forming a combined pixel, the combined pixel comprising a pixel of the red pixel data, a pixel of the blue pixel data, a pixel of the first portion of green pixel data, and a pixel of the second portion of the green pixel data.
6. A digital signal processor (DSP) comprising an instruction set that,
when executed, causes the DSP to perform steps comprising:
receiving, from an image sensor chip, compressed pixel data, the compressed pixel data comprising pixel data organized into a plurality categories and compressed by the image sensor chip at a magnitude of compression selected based on a rate at which the pixel data is captured;
decompressing the compressed pixel data to produce decompressed pixel data organized into the plurality of categories;
combining the categories of decompressed pixel data to produce combined pixel data;
compressing the combined pixel data to produce a digital image comprising a digital image format; and
outputting the digital image.
7. The DSP of claim 6 , wherein each pixel of the decompressed pixel data is organized into a plurality of categories comprising a) either odd column pixel data or even column pixel data, and b) either odd row pixel data or even row pixel data.
8. The DSP of claim 7 , wherein combining the categories of decompressed pixel data comprises interleaving pixel data comprising odd column pixel data and pixel data comprising even column pixel data, and interleaving pixel data comprising odd row pixel data and pixel data comprising even row pixel data.
9. The DSP of claim 6 , wherein the decompressed pixel data is organized into a plurality of categories comprising red pixel data, blue pixel data, a first portion of green pixel data, and a second portion of green pixel data.
10. The DSP of claim 9 , wherein combining the categories of decompressed pixel data comprises forming a combined pixel, the combined pixel comprising a pixel of the red pixel data, a pixel of the blue pixel data, a pixel of the first portion of green pixel data, and a pixel of the second portion of the green pixel data.