Monday, September 01, 2014

Why ISO Changed Resolution Chart

Image Engineering publishes explanations on why ISO changed the resolution chart in Feb. 2014.

"The problems users had with the old chart:
  1. It is defined as a high contrast test chart with a white background. This sometimes causes clipping in the highlights or/and the shadows.
  2. Visual analysis is often impossible
  3. The high contrast edge is subject to sharpening which leads to misleading results when looking at an SFR derived from the edge"

The new chart is sine Siemens star image considered to be better suited for the resolution measurements, although system sharpening can still present a measurement challenge.


  1. Interesting to see that ISO is moving towards the Siemens star. Both methods are discussed in my blogs on As can be expected, both methods have their pros and cons.

  2. For more information on both methods to measure the MTF, see my blog on Both measurement techniques have their pros and cons !

    1. Sorry for this double comment, something went wrong while typing in the first one.

  3. how about low contrast slanted edge?

  4. I notice the new ISO12233 spec defines at least three charts, including a slant edge chart. It seems the European, North American, and Japanese groups couldn't agree on which chart or method is superior. This announcement, by a European member, promotes the European position, neglecting to mention or discuss the merits of the other methods.

  5. How relevant are ISO standards today which CPIQ and others? I like the siemens star method for situations where you cannot control image processing but for all other tasks I prefer slanted edges (easier, no spatial variation).


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