Video Image Pickup Exposure Guide Using Block Luminance Calculation
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Solution Overview
Problem
Video image pickup apparatuses face challenges in accurately displaying exposure guides for photographers familiar with wider dynamic ranges, as knee-processed signals lead to non-linear values that obscure the true brightness of subjects, making it difficult to set exposure effectively.
Innovation Solution
A video image pickup apparatus that includes a solid-state image pickup device, a high-luminance compression processor, a block luminance calculator, a block extractor, a display information generator, and an image superposer to divide images into blocks, calculate luminance indices, and superpose exposure guide information onto the image, allowing for the display of luminance extremes, enabling photographers to grasp the real brilliance of subjects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-luminance compression (knee process) is applied to the picture signal, then the output signal is limited to a white clip point of approximately 109% and can be transmitted to subsequent devices, but the real figure of brightness of the subject cannot be grasped for exposure setup
Solution Approach 1:
The image is divided into multiple blocks, and luminance indices are calculated for each block. This segmentation allows the system to provide detailed local brightness information that reflects the actual scene luminance distribution before compression, enabling accurate exposure assessment while maintaining compressed signal output.
Solution Approach 2:
A block luminance index calculation system serves as an intermediary between the original image signal and the compressed output signal. This intermediary calculates and displays luminance information based on the uncompressed signal, providing photographers with accurate brightness guidance independent of the compression process.
2Ease of operation
If knee-processed picture signal is used for exposure guide display, then the picture signal state for output can be confirmed, but photographers familiar with wider dynamic range cannot set exposure as on film shooting
Solution Approach 1:
The system dynamically switches between displaying compressed signal information and uncompressd signal information based on photographer needs. By providing selectable display modes, the system adapts to different photographer workflows - allowing those familiar with film to use uncompressd signal display for natural exposure judgment, while others can use compressed signal display for output verification.
Solution Approach 2:
The system changes the display parameter from compressed luminance values to uncompressd luminance values. This parameter change allows the display to reflect the actual scene brightness range that photographers are familiar with from film shooting, while the underlying compression process remains intact for proper signal output.
3Loss of information
If the entire image is processed for luminance calculation, then comprehensive exposure information is obtained, but the display becomes complex and difficult to interpret quickly
Solution Approach 1:
By dividing the image into blocks and calculating luminance indices for each, the system organizes comprehensive luminance information into discrete, manageable units. This segmentation makes it easier to identify and display key exposure characteristics without overwhelming the photographer with continuous complex data.
Solution Approach 2:
The system extracts key luminance information from the entire image by calculating representative indices for each block. This extraction process distills comprehensive exposure data into essential metrics that can be quickly interpreted, removing unnecessary complexity while preserving the core exposure information.
Data Source
AI summary
A video image pickup apparatus (10) includes an image sensor (120), a knee processor (132) for performing a compression in a high-luminance characteristic interval of a picture signal based on an output signal of the image sensor, a block luminance calculator (151) for dividing a frame of image based on the output signal of the solid-state image pickup device into a set of blocks, calculating a set of luminance indices of respective blocks, an extreme extractor (152) for extracting a block having a highest luminance index, together with the luminance index, a display information generator (153) for generating a set of pieces of image information for exposure guide display including an image representing a region of the extracted block and an image representing the luminance index, an image superposer (160) for superposing the set of pieces of image information for exposure guide display on a frame of image based on the compressed picture signal to generate a frame of superposed image, and a view finder (170) for displaying the frame of superposed image.