A device that measures the darkness of a material or a reflecting surface.

A densitometer is a device that measures the darkness of a material or a reflecting surface. It consists of a light source aimed at a photoelectric cell. The densitometer measures the sample's darkness from differences in the readings. Modern densitometers also include electronic integrated circuitry for better reading.


  • Transmission densitometers that measure transparent materials
  • A transmission densitometer used to measure transparent surface measures color transparencies film & transparent substrate is some example of common transparent surface measures..
  • Reflection densitometers measure light reflected from a surface.

Photography applications

Some are capable of both types of measurements selectable by a switch. They are used in film photography to measure densities of negatives with the switch in the "T" (Transmission) position and the saturation of a resulting print in the "R" position. Such measurements enable the photographer to choose the right photo paper and the correct exposure, obviating experiments with test strips. Once the papers and darkroom have been calibrated, the first print from a previously measured negative is a success at once.


  • Densitometers are used for measuring color saturation by print professionals
  • Calibration of printing equipment
  • It serves as one of the Molecular tools for gene study, to quantify the radioactivity of a compound such as radiolabeled DNA.
  • They are also used for making adjustments so that outputs are consistent with the colors desired in the finished products.
  • They are used in industrial radiography to ensure x-ray films are within code-required density ranges. They are also used to compare relative material thicknesses.
  • Densitometers are used for process control of density dot gain, dot area & ink trapping.
  • Densitometer readings will be different for different types of printing processes & substrates.


Adapted from content published on
  • Image By J├╝rgen Heiland - 6-09-04, Public Domain — from
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