Focal Stack Color Transfer Preserving Bokeh Quality
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Solution Overview
Problem
Existing color transfer methods fail to preserve the quality of bokeh in out-of-focus areas of images, resulting in non-smooth depth navigation in focal stacks.
Innovation Solution
An apparatus and method that apply the color palette of an all-in-focus image from another scene to a focal stack, propagating the color of in-focus pixels to other layers using a kernel size proportional to the layer position, and estimating colors of out-of-focus pixels through weighted averages based on distance from the focal layer, while maintaining the bokeh quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If color transfer methods are applied to focal stacks, then color palette from example image is transferred to source image, but bokeh quality in out-of-focus areas is not preserved
Solution Approach 1:
The method segments the image processing into two distinct parts: in-focus regions and out-of-focus regions. In-focus pixels are recolored using the example image's color palette, while out-of-focus pixels maintain their original colors to preserve bokeh quality. This segmentation allows independent optimization of color transfer and bokeh preservation.
Solution Approach 2:
Different quality characteristics are applied to different regions of the image. The in-focus regions receive full color transfer processing to achieve the desired color palette, while out-of-focus regions maintain their original appearance to preserve the natural bokeh effect. This local differentiation resolves the contradiction between color transfer and bokeh quality.
2Ease of manufacture
If color transfer is applied to focal stacks, then colors are modified according to color palette, but depth navigation becomes non-smooth
Solution Approach 1:
The method segments the processing by depth plane, applying color transfer only to in-focus planes while leaving out-of-focus planes unchanged. This creates smooth transitions between depth planes during navigation, as only the currently in-focus region undergoes color modification, preventing abrupt color changes that would disrupt navigation smoothness.
Solution Approach 2:
Different processing quality is applied locally to different depth planes. The in-focus depth plane receives color transfer processing, while out-of-focus depth planes maintain their original appearance. This local quality differentiation ensures smooth depth navigation by preventing discontinuities in the visual appearance across different focus planes.
Data Source
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AI summary
The present invention generally relates to colour transfer between two images. Colour transfer is a known technic consisting in modifying the colours of a source image by applying the colour palette of an example image without changing the source image structure. A lot of colour transfer method are known which consist in transferring colours between two images, however, those methods do not preserve the quality of the bokeh in areas of an images that are not in focus at a given depth. This results in a navigation in the depth dimension that is not smooth. It is proposed to modify the colours of a focal stack of a scene according to a colour palette by propagating the colours of the pixels in focus in different layers of the recoloured focal stack to the layers of the recoloured focal stack located behind the layer wherein a considered pixel is in focus.