Efficient Sandstorm Image Enhancement Using the Normalized Eigenvalue and Adaptive Dark Channel Prior

Abstract

A sandstorm image has features similar to those of a hazy image with regard to the obtaining process. However, the difference between a sand dust image and a hazy image is the color channel balance. In general, a hazy image has no color cast and has a balanced color channel with fog and dust. However, a sand dust image has a yellowish or reddish color cast due to sand particles, which cause the color channels to degrade. When the sand dust image is enhanced without color channel compensation, the improved image also has a new color cast. Therefore, to enhance the sandstorm image naturally without a color cast, the color channel compensation step is needed. Thus, to balance the degraded color channel, this paper proposes the color balance method using each color channel’s eigenvalue. The eigenvalue reflects the image’s features. The degraded image and the undegraded image have different eigenvalues on each color channel. Therefore, if using the eigenvalue of each color channel, the degraded image can be improved naturally and balanced. Due to the color-balanced image having the same features as the hazy image, this work, to improve the hazy image, uses dehazing methods such as the dark channel prior (DCP) method. However, because the ordinary DCP method has weak points, this work proposes a compensated dark channel prior and names it the adaptive DCP (ADCP) method. The proposed method is objectively and subjectively superior to existing methods when applied to various images.

Efficient Sandstorm Image Color Correction Using Rank-Based Singular Value Recombination

“…Al Ameen's method [9] enhances color-degraded sandstorm images using the gamma correction. Lee enhanced degraded sandstorm images using the normalized eigenvalue [16].…”

“…The Al Ameen method [9] uses a constant value to enhance sandstorm images, and the enhanced image's artificial color shift occurs because the constant value does not reflect the image's feature adaptively. The enhanced images produced using the Lee method [16] seem bright, because to enhance the degraded sandstorm images, Lee's method [16] uses the normalized eigenvalue, and due to this, the enhanced images have a bright region; the eigenvalue of the red channel is more abundant than that of other color channels. However, the enhanced images produced using the proposed method enhance the color components of degraded sandstorm images naturally without any color shift.…”

“…Al Ameen's method [9] enhances the sandstorm images; however, the enhanced images using this method have an artificial color shift due to using a constant value to enhance the distorted color, and it does not reflect the image's features. The improved images produced using the Lee method [16] have a bright region due to the abundant red channel. Meanwhile, the enhanced images produced using the proposed method have no artificial color shift.…”

“…However, an artificial color cast appears in the enhanced image. Lee enhanced sandstorm images using the normalized eigenvalue and adaptive dark channel prior [16].…”

CADCP: a method for chromatic haze compensation on remotely sensed images

“…We are focused on the special type of distortions: partial absorbing and scattering in opaque mediums. The problem of compensating for such distortions is known under different names depending on the type of opaque medium: dehazing [8,9], smoke removal [10], thin cloud removal [11], sandstorm image enhancement [12]. All these types distortions are of a common nature and we will consider compensation problems of these all types together under the name of dehazing.…”