Raw image filtering based on the generalized method of least modules

This article studies the filtering of RAW images obtained from a photo matrix. The article adapts a filter based on the generalized method of least modules (GMLM) for filtering RAW images from digital cameras. Digital images obtained by digitizing an analog signal with a digital photo matrix have a noise component in addition to the useful signal. The image structure obtained directly from the digital matrix is very different from the usual RGB image. It is necessary to apply a demosaicing algorithm to obtain an RGB image, which introduces additional distortions. It is proposed to filter the resulting image before applying the demosaicing algorithm. RAW images use more bits to describe the brightness of each pixel than standard RGB images and have a different structure. The adaptation of existing digital filters is required to work with such images. For GMLM filtering, coefficients for the parameters of the smoothing transformation function are selected. The advantages of filtering RAW images in comparison with standard RGB images and a comparison of GMLM with averaging and median filtering are shown. Based on the obtained dependencies, the practical problem of increasing the contrast in images of glass insulators based on their RAW images for the subsequent detection of defects in insulators is solved.