Editing JPEG File Interchange Format (section)

=== Color space ===

The JPEG standard used for the compression coding in JFIF files does not define which [[color space|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 model|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 white by Y=235 and values outside of this range are available for signal processing "headroom" and "footroom", JFIF uses all 256 levels of the 8-bit representation, so that Y=0 for black and Y=255 for peak white. The RGB color primaries defined in JFIF via CCIR 601 also differ somewhat from what has become common practice in newer applications (e.g., they differ slightly from the color primaries defined in [[sRGB]]). Moreover, CCIR 601 (before 2007) did not provide a precise definition of the RGB color primaries; it relied instead on the underlying practices of the television industry.

Color interpretation of a JFIF image may be improved by embedding an [[International Color Consortium|ICC]] profile, colorspace metadata, or an [[sRGB]] tag, and using an application that interprets this information.