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Digital photograph flash lamp shadow detection method

A shadow detection and flash technology, applied in image data processing, instrumentation, computing, etc., to solve problems such as color oversaturation

Inactive Publication Date: 2014-01-22
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the use of flash will also cause many unfavorable factors, such as color oversaturation, red eye, flash shadow, etc.

Method used

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  • Digital photograph flash lamp shadow detection method
  • Digital photograph flash lamp shadow detection method
  • Digital photograph flash lamp shadow detection method

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Experimental program
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Embodiment Construction

[0020] The present invention will be described below with reference to the accompanying drawings and embodiments.

[0021] Denote flash images and no flash images by FL and NF, respectively, and assume that FL and NF satisfy the following three assumptions:

[0022] Condition 1: The time interval between shooting FL and NF is very short, and the relative position of the lens and the shooting scene remains basically unchanged.

[0023] Condition 2: The foreground target area is more susceptible to the flash effect than the background area, and the brightness value changes more obviously.

[0024] Condition 3: The flash shadow appears in the background area around the foreground object and is adjacent to the foreground object.

[0025] The proposed scheme is divided into three steps: preprocessing, shadow edge point detection and shadow region segmentation.

[0026] 1 Preprocessing

[0027] Preprocessing includes three processes: grayscale, image smoothing and image registrat...

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Abstract

The invention belongs to the field of color image processing in the computer vision field, and relates to a digital photograph flash lamp shadow detection method. The method comprises that: three preprocessing procedures of graying, image smoothing and image registering are performed on two images in turn; step two, shadow edge point detection is performed, and the steps of the shadow edge point detection are listed as follows: a Sobel arithmetic operator is utilized to extract edge binary images of the two images processed by graying; edge differential images DBM of the two images are calculated, and potential flash lamp shadow edge points are marked; expansion processing is performed, connected regions of expanded result images are marked, the number of pixel points in each connected region is calculated, foreground regions are extracted and the flash lamp shadow edge points are obtained; and differential binary images DM are calculated and shadow regions are extracted. The shadow regions appearing in a flash lamp photograph can be effectively segmented by the digital photograph flash lamp shadow detection method so as to be ready for subsequent shadow-removing operation.

Description

Technical field [0001] The present invention relates to the field of color image processing in the field of computer vision, in particular to the aspect of shadow detection for color digital photos. Background technique [0002] With the improvement of people's quality of life, consumer-grade digital cameras have become a must-have item for ordinary households in China. Its use brings fun and convenience to people's life and work. When taking digital photos, especially indoor photos in poor lighting conditions, it is often necessary to use a flash to increase the light intensity when shooting, so that the details of people or objects in the foreground are more obvious. However, the use of flash can also cause many unfavorable factors, such as color oversaturation, red eye, flash shadows and so on. Among them, the flash shadow refers to the shadow area that appears on the background because the foreground object blocks the light of the flash. We call this type of shadow "f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/00
Inventor 王建刘立曹群吴静媛
Owner TIANJIN UNIV