A patch chart is a test strip or chart composed of a series of coloured or grey squares, commonly used in colour printing, especially with the additive method. Each patch represents a specific exposure, density, or colour value, helping photographers and printers evaluate tonal range, colour accuracy, and printing consistency.
Patch charts are valuable tools for calibrating equipment, checking colour balance, and ensuring reproducible results in both darkroom and digital workflows. They allow precise adjustments to achieve the desired output before final printing.