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Calibration 1

Calibration

Photopedia

18 October 2007 15:06


The aim of colour calibration is to adjust the colours of one output device to match those of another, and in the context of digital photography the most common form of calibration involves adjusting a computer monitor and printer, with the aim of producing a print that appears identical in saturation and dynamic range to the same image when it is displayed on the computer’s monitor. This requires two independent calibrations to be performed:

1. Calibration of the computer monitor display to ensure accuracy when representing the colours of the color space used for the image file

2. Calibration of the printer, which needs to match the colour output of the computer display.

Attempting calibration of a monitor display using the naked eye simply does not provide sufficient accuracy, so the use of an external calibration device is essential. There are a variety of products available but most work on the same principle: a sensor in the calibration device is placed close to the surface of the monitor screen, whilst calibration software sends a series of colour signals of known value to the monitor and compares these against the readings from the calibration device.

The difference in colour values is calculated and then depending on the type of calibration software it will either create a file to correct the colour values (often referred to as an ICC profile) before they are displayed, or create a set of instructions that alter the brightness/contrast and RGB values of the display.

Printer calibration involves the calibration software sending a test print to the printer and comparing the result with the original file with the use of the external calibration device. It is important to establish a calibration profile for each combination of printer/paper/ink that is used.