Monochrome Image Generation via Gradient-Weighted RGB De-mosaicing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image capturing devices with color filters often produce color images with reduced sharpness due to the weighting of blue and red channels, limiting the modulation transfer function (MTF) of monochrome video conversion from color video.
Innovation Solution
A method that de-mosaics RGB data, applies a median operation for noise reduction, calculates local gradients, and assigns weights to each pixel to generate a monochrome image from raw data, enhancing MTF without removing the color filter array, using a single-chip digital image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If color video is converted to monochrome by simply stripping the chroma at the final stage of processing, then the conversion process is simple, but the modulation transfer function (MTF) of the resulting monochrome video is limited and similar to that of the color video
Solution Approach 1:
The patent applies preliminary action by performing noise reduction and gradient-based weighting calculations on the RGB channels before combining them to form the monochrome image. Instead of simply stripping chroma from the final color video, the method pre-processes each color channel individually through median filtering and gradient calculations, then combines them with optimized weights to achieve superior MTF while maintaining reasonable processing complexity
Solution Approach 2:
The patent applies local quality by calculating separate weights for each RGB channel based on local gradient magnitudes at each pixel position. The weighting scheme adapts locally to the image content, assigning higher weights to channels with stronger local gradients in specific regions, thereby optimizing the MTF contribution of each channel in different spatial locations
2Device complexity
If a color filter array is used over a single-chip digital image sensor to capture color images, then the device structure is compact and cost-effective, but the sharpness of the resulting images is reduced
Solution Approach 1:
The patent applies parameter changes by transforming the RGB color data into a monochrome intensity representation through a weighted sum operation. The weights are dynamically calculated based on local gradient properties, effectively changing the parameter combination (weighting ratios of R, G, B channels) to optimize sharpness and MTF while preserving the compact single-chip sensor structure with color filter array
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Systems and methods are described for generating a monochrome image from a color filter array. Image data from an image capturing device may be received having a color filter array comprising a plurality of filter positions. The image data may be interpolated to de-mosaic the image data into three sets of data representing red, blue, and green (RGB) data, respectively, for each of the plurality of filter positions. A weight may be calculated for each value of the RGB data based on a local gradient calculated for each value of the RGB data. A pixel value may be calculated for each pixel position for generating a monochrome image using the weight for each value of the RGB data.