Operate Image Log For Free

Log transformation is used for image enhancement as it expands dark pixels of the image as compared to higher pixel values. The formula for applying log transformation in an image is, S = c * log (1 + r) where, R = input pixel value, C = scaling constant and S = output pixel value.

L og transformation first compresses the dynamic range and then upscales the image to a dynamic range of the display device. In this way, lower values are enhanced and thus the image shows significantly more details.

Log transformation of gives actual information by enhancing the image. If we apply this method in an image having higher pixel values then it will enhance the image more and actual information of the image will be lost. So, this method can't be applied everywhere.

The inverse log transform expands the values of light-level pixels while compressing the darker-level values. Note: s,r: denote the gray level of the input pixel and the output pixel. 'c' is a constant; to map from [0,255] to [0,255], c =LOG(256)/255.

It is mathematically defined as, S=C log(1+r) where C is any constant and r, s are input and output pixel values. LOG transform enhances small magnitude input values into wider range of output pixel values and compresses large magnitude input values into narrow range of output values.

Borehole imaging tools collect high-resolution images of an open or cased borehole wall by employing an optical, acoustic, or electrical sensor or sensor array. Optical imaging techniques (e.g., optical televiewer and television logging) directly depict the borehole interior via photography or videography.

Dynamic range refers to the ratio of max and min intensity values. When the dynamic range of the image is greater than that of displaying device(like in Fourier transform), the lower values are suppressed. To overcome this issue, we use log transform.