PhotometricInterpretation

Photometric interpretation is a metadata attribute used in digital imaging, especially in the DICOM standard, that specifies how the pixel data should be interpreted to produce a meaningful image. It identifies the color model and the intended mapping of pixel sample values to brightness and color, and thus governs how an image is displayed and processed. Correct interpretation is essential for accurate visualization and subsequent analysis.

Common values describe grayscale images or color representations. MONOCHROME1 indicates a grayscale image where higher pixel values correspond to darker display luminance (inverted grayscale), whereas MONOCHROME2 uses the conventional mapping where higher values are brighter. RGB indicates a true color image with separate red, green, and blue samples for each pixel. PALETTE COLOR denotes indexed color, where pixel values are treated as indices into a color lookup table that defines the final RGB colors.

Other color models used in various formats include YBR (often YBR_FULL, YBR_FULL_422, and related variants), which store luminance and chrominance components that are later transformed to RGB for display. The Photometric Interpretation value is stored with the image metadata and must be respected by viewers and processing software; misinterpretation can lead to inverted grayscale, incorrect colors, or distorted images. In practice, it guides rendering, color management, and any color space conversions applied during display or analysis.