The JPEG File Interchange Format (JFIF) is an image file format standard published as ITU-T Recommendation T.871 and ISO/IEC 10918-5. It defines supplementary specifications for the container format that contains the image data encoded with the JPEG algorithm. The base specifications for a JPEG container format are defined in Annex B of the JPEG standard, known as JPEG Interchange Format (JIF). JFIF builds over JIF to solve some of JIF's limitations, including unnecessary complexity, component sample registration, resolution, aspect ratio, and color space. Because JFIF is not the original JPG standard, one might expect another mime-type. However, it is still registered as "image/jpeg" (indicating its primary data format rather than the amended information). JFIF is mutually incompatible with the newer Exchangeable image file format (Exif). Purpose JFIF defines a number of details that are left unspecified by the JPEG Part 1 standard (ISO/IEC 10918-1, ITU-T Recommendation T.81.) Component sample registration JPEG allows multiple components (such as Y, Cb, and Cr) to have different resolutions, but it does not define how those differing sample arrays (which render bitmaps) should be aligned. This pixel-producing information is rendered with the expectation of indicating rectangles by their centeroid, rather than being pixel data directly, or being 'first corner and flood', etc. which is uncommon. Resolution and aspect ratio The JPEG standard does not include any method of coding the resolution or aspect ratio of an image. JFIF provides resolution or aspect ratio information using an application segment extension to JPEG. It uses Application Segment #0, with a segment header consisting of the null-terminated string spelling "JFIF" in ASCII followed by a byte equal to 0, and specifies that this must be the first segment in the file, hence making it simple to recognize a JFIF file. Exif images recorded by digital cameras generally do not include this segment, but typically comply in all other respects with the JFIF standard. Color space The JPEG standard used for the compression coding in JFIF files does not define which color encoding is to be used for images. JFIF defines the color model to be used: either Y for greyscale, or YCbCr derived from RGB color primaries as defined in CCIR 601 (now known as Rec. ITU-R BT.601), except with a different "full range" scaling of the Y, Cb and Cr components. Unlike the "studio range" defined in CCIR 601, in which black is represented by Y=16 and