Image Processing Gain Application for Dynamic Range Reduction

Solution Overview

Problem

High dynamic range images captured by cameras using HDR techniques often need to be reduced in dynamic range for display on devices with limited bit depth, leading to loss of detail in both dark and light areas, especially in images with large areas of very dark and very light pixels.

Innovation Solution

An image processing method that applies a first gain to pixels with brightness values below a threshold to increase their brightness and a second gain to pixels above the threshold to decrease their brightness, followed by a conversion process to represent the image with a lower dynamic range, preserving detail in both areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If HDR techniques are used to capture images with high dynamic range, then the dynamic range of captured images is improved, but the device complexity increases due to multiple image capture and combination processes

Engineering Contradiction:

Improvedynamic rangeVSAvoiddevice complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent changes the parameter of pixel brightness values by applying different gain factors to different brightness ranges. This transforms the HDR image data into a format suitable for SDR display while preserving detail information through selective brightness adjustment in shadow and highlight regions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different processing treatments to different regions of the image based on local brightness characteristics. By identifying shadow regions (low brightness) and highlight regions (high brightness) separately and applying targeted gain adjustments, the method preserves local detail quality that would otherwise be lost in global tone mapping.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the dynamic range of captured images is reduced for display on devices with limited bit depth, then the ease of operation is improved, but the loss of information increases in both dark and light areas

Engineering Contradiction:

Improveease of operationVSAvoidloss of information

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent applies different processing treatments to different regions of the image based on local brightness characteristics. By identifying shadow regions (low brightness) and highlight regions (high brightness) separately and applying targeted gain adjustments, the method preserves local detail quality that would otherwise be lost in global tone mapping.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of pixel brightness values by applying different gain factors to different brightness ranges. This transforms the HDR image data into a format suitable for SDR display while preserving detail information through selective brightness adjustment in shadow and highlight regions.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If a single gain is applied to all pixels to reduce dynamic range, then the device complexity is reduced, but the loss of information increases particularly in shadow and highlight regions

Engineering Contradiction:

Improvedevice complexityVSAvoidloss of information

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The patent applies different processing treatments to different regions of the image based on local brightness characteristics. By identifying shadow regions (low brightness) and highlight regions (high brightness) separately and applying targeted gain adjustments, the method preserves local detail quality that would otherwise be lost in global tone mapping.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the image processing into distinct operations for different brightness regions. By separating shadow region processing from highlight region processing and applying appropriate gain factors to each segment, the method prevents information loss that would occur with uniform single-gain application.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10298857B2Image processing method and apparatus, integrated circuitry and recording medium for applying gain to a pixel

Publication Date: 2019.05.21 SONY GROUP CORP

AI summary

An image processing method comprising: receiving a first image signal representing a portion of a captured image with a first dynamic range; generating a second image signal using the first image signal: applying one of: a first gain to the brightness value of each pixel in the portion of the captured image represented by the first image signal having a brightness value less than a first threshold brightness value, the first gain serving to increase the brightness value of each pixel to which it is applied, and a second gain to the brightness value of each pixel in the portion of the captured image represented by the first image signal having a brightness value greater than a second threshold brightness value, the second gain serving to decrease the brightness value of each pixel to which it is applied; and after the application of the one of the first and second gains, performing a conversion process such that the brightness value of each pixel in the portion of the captured image represented by the first image signal becomes represented in the second format, thus forming the second image signal.