Mobile Camera Focus Sweeping for All-In-Focus Imaging
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Solution Overview
Problem
Mobile cameras with shallow depth-of-field struggle to capture high-quality all-in-focus images, particularly in scenarios requiring multiple objects at different focal distances to be in focus, such as landscape or medical photography, due to limitations in existing technologies for quick and responsive image capture.
Innovation Solution
User equipment with depth, contrast, or phase-detection sensors segments the field-of-view into focal distances, sweeps an autofocus lens to capture images at each distance, and combines these images to produce an all-in-focus image, utilizing a buffer to minimize shutter lag and optimize lens movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shallow depth-of-field is used in mobile cameras, then portrait quality and artistic photography are improved, but the ability to capture all-in-focus images is worsened
Solution Approach 1:
The patent segments the field of view into multiple depth ranges (foreground, midground, background) and captures separate images for each segment by sweeping the autofocus lens through different focal distances. This segmentation allows the system to overcome the shallow depth-of-field limitation by taking multiple images at different focus planes and then combining them computationally to produce an all-in-focus image.
Solution Approach 2:
The patent performs preliminary actions by capturing multiple images at different focal distances before final image generation. The autofocus lens is swept through various focal planes and images are captured in advance, allowing the system to have ready-made data for computational combination to produce the final all-in-focus image.
2Manufacturing precision
If multiple images are captured at different focal distances, then all-in-focus image quality is improved, but capture time and responsiveness are worsened
Solution Approach 1:
The patent uses a buffer to store previously captured images that can be reused for all-in-focus generation. When generating a new all-in-focus image, the system checks the buffer first and reuses existing images where applicable, avoiding the need to capture all images again. This preliminary storage and reuse mechanism significantly reduces capture time while maintaining image quality.
Solution Approach 2:
The patent recovers and reuses previously captured images from the buffer instead of discarding them. By recovering and reusing existing image data, the system avoids redundant capture operations and reduces the time required to generate all-in-focus images while maintaining the quality benefits of multi-distance capture.
3Manufacturing precision
If the autofocus lens sweeps through all focal distances, then complete focus coverage is improved, but sweep time and processing speed are worsened
Solution Approach 1:
The patent applies partial action by sweeping the autofocus lens through only the necessary focal distances required for the current image generation task, rather than always sweeping through all possible focal distances. The system determines which focal distances are needed based on the scene content and buffer availability, reducing unnecessary lens movement and improving generation speed while maintaining adequate focus coverage.
Solution Approach 2:
The patent recovers previously captured images from the buffer and reuses them, which eliminates the need to re-sweep the autofocus lens through all focal distances for images that can be generated from buffered data. This recovery mechanism significantly reduces lens sweep time and improves overall image generation productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables mobile devices to generate high-quality all-in-focus images efficiently, maintaining the ability to capture narrowly-focused portraits while addressing the limitations of shallow depth-of-field for diverse photography needs.
Implementation Method 1
sweeping an autofocus lens of the mobile camera to one or more of the focal distances from the set of focal distances, and capturing a sample image at each of the one or more of the focal distances
Implementation Method 2
a lens driven by a voice coil motor (VCM) or a microelectromechanical (MEMS) magnetic actuator
Data Source
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AI summary
The present disclosure describes systems and techniques directed to producing an all-in-focus image with a camera of a mobile device, in particular, cameras with shallow depth-of field. User equipment includes a sensor for determining distance to an object in a camera's field-of-view. Based on a depth map of the field-of view, a plurality of segments is inferred, each segment defining a unique focus area within the camera's field-of-view. An autofocus lens of the camera sweeps to a respective focal distance associated with each of the plurality of segments. The camera captures sample images at each focal distance swept by the autofocus lens. The user equipment produces an all-in-focus image by combining or merging portions of the captured sample images.