JPEG MCU Redefinition for Lossless Image Rotation
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Solution Overview
Problem
Conventional imaging systems that produce rotated JPEG images suffer from data loss and require expensive processing and memory storage due to the need for differential encoding changes when rotating images, as they must decompress, rotate, and re-compress images, which affects image quality.
Innovation Solution
The system employs image processing and data formatting circuitry to mirror and non-raster readout image data, allowing for rotation of image blocks and redefinition of minimum coded units (MCUs) to maintain consistent encoding order, reducing the need for padding and interpolation, and storing only necessary DCT coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional JPEG rotation is performed by decompressing, rotating, and re-compressing the image, then the image can be rotated to different orientations, but data loss occurs and image quality deteriorates
Solution Approach 1:
The patent applies preliminary action by performing the rotation operation during the JPEG compression process itself, rather than after compression. The rotation is incorporated into the compression pipeline at the block arrangement stage, so that rotated images are generated directly during compression without requiring subsequent decompression and re-compression operations, thereby preventing additional data loss
Solution Approach 2:
The patent uses copying by creating rotated versions of image blocks and arranging them in rotated MCUs according to rotation parameters. Instead of rotating the entire compressed image, the system copies and repositions individual blocks during compression, generating rotated image variants that maintain compression efficiency and image quality
2Adaptability or versatility
If JPEG images are rotated by rearranging pixel blocks in MCUs, then rotated orientations are achieved, but expensive processing and memory storage are required for differential encoding
Solution Approach 1:
The patent applies parameter changes by modifying the MCU structure parameters based on rotation angles. Different rotation angles (90°, 180°, 270°) correspond to different MCU configurations, allowing the system to optimize processing requirements for each rotation type. The encoder adjusts MCU parameters dynamically according to the desired rotation, reducing the need for complex universal processing logic
Solution Approach 2:
The patent applies segmentation by dividing the image into MCUs and further into 8x8 pixel blocks that can be independently arranged during compression. This segmentation allows rotated images to be constructed by repositioning pre-compressed blocks without requiring full decompression, significantly reducing processing complexity and memory requirements compared to conventional rotation methods
Data Source
AI summary
An imaging system may include an image sensor array and circuitry that rotates and encodes images from the image sensor array. The circuitry may encode images from the image sensor into an image format such as a Joint Photographic Experts Group (JPEG) format. The circuitry may perform rotations of the images during encoding into Joint Photographic Experts Group (JPEG) format. Image rotations during encoding and compression may include redefining minimum coded units of the encoded image such that minimum coded units of a rotated image are processed in the same order as minimum coded units in a non-rotated image. Redefinition of minimum coded units may include rewriting of parameters in a start of frame segment of an image data stream such that the height and width of minimum coded units are reversed during rotation.