Although aesthetically displeasing, tannins do not pose a health issue. However, if tannins are found in the water, it can indicate that your water is significantly influenced by surface water. Put simply, this means that if tannins can travel easily from surface water to your groundwater source, pathogens can easily travel through as well.
JPG is a file extension for a lossy graphics file. The JPEG file extension is used interchangeably with JPG. JPEG stands for Joint Photographic Experts Group who created the standard. JPG files have 2 sub-formats, JPG/Exif (often used in digital cameras and photographic equipment), and JPG/JFIF (often used on the World Wide Web).
The Exif and JFIF standards define the commonly used formats for interchange of JPEG-compressed images. A JPG file consists of a sequence of segments, each beginning with a marker, each of which begins with a 0xFF byte followed by a byte indicating what kind of marker it is. Some markers consist of just those two bytes; others are followed by two bytes indicating the length of marker-specific payload data that follows.