${\displaystyle R-Y}$ indicates a color difference signal between red (R) and a luminance component, as part of a luminance (Y) and chrominance (C) color model. It has different meanings depending on the exact model used:

• V in YUV, a generic model used for analog and digital image formats;
• Cr in YCbCr, used for digital images and video;
• Pr in YPbPr, used in analog component video;
• Dr in YDbDr, used in analog SECAM and PAL-N;