Compact Camera Narrow Depth-of-Field Image Processing
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Solution Overview
Problem
Compact digital cameras struggle to produce narrow depth-of-field images due to their smaller imaging area and shorter focal distance, making it difficult to achieve an out-of-focus effect where the subject is in focus and the background is blurred.
Innovation Solution
An image processing method that captures three images with different focuses – one with the subject focused, one with the background focused, and a super-macro image not focused – and combines these using a Difference of Gaussian filter to separate the subject and background, allowing for image processing to enhance the out-of-focus effect by sharpening the subject, blurring the background, adjusting brightness, and adjusting chroma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a compact digital camera is used, then the device is portable and compact, but the depth of field becomes large making it difficult to obtain narrow depth-of-field images
Solution Approach 1:
The patent divides the image into subject portion and background portion using difference of Gaussian (DoG) filter, then processes each portion separately. The subject portion is sharpened while the background portion is blurred, creating narrow depth-of-field effect in compact cameras that naturally have deep depth of field.
Solution Approach 2:
The patent applies different processing qualities to different regions of the image. The subject portion receives sharpening treatment while the background portion receives blurring treatment, creating localized quality differences that simulate narrow depth-of-field effect without requiring optical changes.
2Area of stationary object
If the focal distance of a lens is shortened, then the imaging area becomes smaller suitable for compact cameras, but the depth of field becomes larger
Solution Approach 1:
The patent replaces the optical mechanism (lens focal length adjustment) with a digital image processing mechanism. Instead of changing the physical focal distance to achieve narrow depth of field, the system uses DoG filter-based segmentation and selective sharpening/blurring to create the same visual effect digitally.
Solution Approach 2:
The patent changes the processing parameters (sharpness and blur levels) of different image regions to achieve the desired depth-of-field effect. By adjusting the degree of sharpening for the subject portion and blurring for the background portion, the system creates narrow depth-of-field appearance without changing optical parameters.
3Length of moving object
If multiple images with different focuses are captured and processed, then narrow depth-of-field effect is achieved, but the processing time and complexity increase
Solution Approach 1:
The patent performs preliminary image capture with multiple focus settings (subject-focused, background-focused, and super-macro images) before the actual processing. This preliminary preparation allows the system to have ready-made image data that can be quickly segmented and processed to create narrow depth-of-field effect.
Solution Approach 2:
The patent uses difference of Gaussian (DoG) filter as an intermediary tool to compare and differentiate between multiple captured images. The DoG filter serves as a mediator that identifies subject and background portions by calculating frequency domain differences, simplifying the complex task of image segmentation.
Data Source
AI summary
Disclosed are example methods and apparatuses for image processing for improving an out-of-focus effect. A disclosed example methods includes capturing a first image, a second image, and a third image, which are captured with a different focus for a same subject and background; setting a subject portion and a background portion using the first and second images; combining the subject portion of first image and the background portion of the third image with each other to obtain an narrow depth-of-field (DOF) image; and performing image processing on the obtained narrow DOF image.