How do you measure resolution?

What is Resolution?

Resolution is the ability of an imaging system to reproduce spatial frequencies. Some people simply use the resolution to describe the limiting resolution, but it can also show the comprehensive information relating to the ability of a camera to reproduce low, mid and high frequencies in various contrasts. Spatial frequencies are what natural image content is made of, so it important to know how your camera can work with this content.

All of the charts shown here will help you learn more about the resolution and the image quality of your devices.

Line Pattern Chart

01 line pattern

What is it?

  • A chart with sharp black and white lines in different frequencies arranged in a horizontal or vertical direction.
  • Different patterns available for different pixel counts of cameras, i.e. SDTV, HDTV, 4K or 8K.

How to use it?

  • Best to use in combination with a waveform monitor.
  • Measurements from the waveform monitor will follow a single line (or all lines as an overlay) of the image.
  • The waveform monitor will show either a high or low signal somewhere on or between black and white (the line patterns in the chart are black and white) from 0% to 100%.

What can we learn from it?

06 waveform monitor

The green horizontal lines through the captured patterns cross different frequencies. A resolved frequency will be seen as a distinctly changing signal between black and white (left side). If the frequency is too high, the signal displayed on waveform monitor will stop toggling between black and white and the pattern will no longer be clear because the camera will just capture “gray” (right side).

  • If the modulation is too low, there will be no divide between the black and white signal, which is roughly the limiting frequency.
  • High frequencies will be less likely to show black and white and will appear as grey (called modulation drops).

When to use it?

  • If you are working in broadcast production.
  • If you are responsible for the maintenance of imaging equipment
  • If you have a waveform monitor readily available
  • If just quick checks are needed for the camera

Siemens Star Chart

02 Siemens star

What is it?

  • Siemens star charts are based on black and white sectors. For a resolution measurement (according to ISO 12233), the change between black and white shows a sine wave shape.
  • Each star in the image offers many different frequencies such as low frequencies at the outer radius and high frequencies at the inner radius.

How to use it?

  • The center of the chart is covered by a registration mark used for software based, automated detection. Each star modulation is checked for many radii by the software.
  • Results are combined to form a diagram called the MTF curve.
  • Same frequencies are measured at 25 spots in the image.
  • This measurement is always objective.

What can we learn from the MTF?

  • The limiting frequency of your system.
  • The resolving performance of a camera for low to high frequencies.
  • The image sharpness during the image processing.
  • Resolution can be checked in horizontal, vertical a few diagonal directions.
  • To learn more about Siemens star measurements, have a look in our technotes.

04 MTF1

05 MTF2

Camera 1 shows higher modulation for mid and high frequencies meaning better reproduction of these frequencies.

Camera 2 drops faster to zero and so is not able to resolve higher frequencies.

Dead Leaves Chart

03 Dead Leaves

What is it?

  • A Dead Leaves chart is a chart with randomly positioned circles with random sizes and RGB values.
  • It is intended to be more closely related to real image content.

How to use it?

  • This chart is used for a specific case of resolution testing called texture loss (high frequencies with low contrast i.e. hair).
  • Results are displayed in a spectral distribution curve similar to MTF, but in this case called SFR.

What can we learn from it?

  • We can measure texture loss.
  • Learn more about the Dead Leaves method from our library.

When to use Siemens Star charts and Dead Leaves charts?

  • If you are developing cameras.
  • If you are a research and development engineer.
  • If you are using/developing devices for broadcasting, VR, and other multimedia applications.
  • If you are choosing a specific high-quality lens.

All of these charts and more will be on display at the IBC 2017. Stop by our booth (hall 12 number E16) and let out engineers show you how you can more accurately measure the resolution of your device. We hope to see you there!

You can also contact us at with any further questions.