The invention discloses a nonlinear
underwater image
gain algorithm for hyperbolic tangent deformation function transformation. The problems of obvious
noise pollution,
low contrast ratio, low brightness, low saturation, color
distortion and the like of
underwater optical images due to
water transparency, light and the like can be obviously improved through
algorithm transformation of the invention. Firstly, an
underwater grating image file is read as matrix data, three
layers of matrix data of RGB three channels are extracted respectively, a hyperbolic tangent deformation-based function with an expansion coefficient k is constructed, the
gain degree and the key
gain color
gradation range can be controlled through the appropriate expansion coefficient k, and a hyperbolic tangent deformation function is constructed; the function is used to carry out gain transformation on three
layers of matrix data of three channels of RGB, and then the three color channels are merged and converted into a new image. The underwater
optical image is processed through the
algorithm, the contrast and brightness of the underwater image are improved, important color
gradation is reasonably redistributed, and the dark area and the color
gradation are improved while detail information of the image is reserved and even enhanced.