Image Processing Apparatus Bit Extension White Balance Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital RAW image data, when subjected to white balance correction, can exhibit quantization errors that result in visible false colors due to differing error magnitudes across color signals, particularly noticeable in achromatic areas.
Innovation Solution
An image processing apparatus and method that extend an N-bit color video signal to an M-bit signal, followed by level correction based on the difference (M-N), and then apply white balance correction to minimize quantization errors and false colors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If white balance correction is applied directly to N-bit RAW image data, then processing speed is maintained, but quantization errors are enlarged and false colors become visible
Solution Approach 1:
The patent applies bit extension (converting N-bit data to M-bit data where M>N) before white balance correction processing. This preliminary action increases the precision of the digital signal, allowing subsequent multiplication by white balance gains without enlarging quantization errors to visible false colors. The extension is performed in advance of the correction operation.
Solution Approach 2:
The patent changes the bit depth parameter of the digital signal from N bits to M bits (where M>N) to improve the precision of color representation. This parameter change allows the system to maintain higher accuracy during white balance correction while preventing the manifestation of quantization errors as false colors in the final image.
2Measurement precision
If bit extension is performed before white balance correction, then false colors are reduced, but processing complexity increases
Solution Approach 1:
The bit extension is performed as a preliminary step before white balance correction, converting N-bit RAW data to M-bit data. This preliminary preparation simplifies the subsequent correction process by ensuring sufficient precision is already in place, avoiding the need for complex error correction algorithms during the main processing stage.
Solution Approach 2:
The extended bit depth (M-bit) acts as an intermediary representation that bridges the gap between the original N-bit data and the requirements for accurate white balance correction. This intermediate form allows precise mathematical operations without immediately manifesting quantization errors, serving as a buffer that simplifies the correction process.
Data Source
AI summary
An image processing apparatus includes a processor including hardware, the processor being configured to extend an N-bit color video signal to an M (M>N)-bit color video signal, subject the M-bit color video signal obtained by the extension to level correction based on (M−N), and subject the color video signal subjected to the level correction to white balance correction.