ICDM Updates Contrast Metrology Text

SID’s International Committee on Display Metrology (ICDM) held an evening meeting at DisplayWeek. The main business was to vote on some new language that was added to one measurement technique and a second section where the results are used to derive resolution. The new language was adopted, marking the culmination of a significant effort by the Spatial subcommittee. But the discussion around this topic is not over – now the group must consider redefining contrast measurement and perhaps the definition of resolution entirely for a version 2 issuance of the metrology standard.ICDM LogoC3 sid small

The three sections whose updates were approved at the SID evening meeting are listed below. Over 70 members attend and the measures were overwhelmingly approved.

  • Section 7 (chapter introduction)
  • 7.2 (Grille Luminance & Contrast)
  • 7.8 (Resolution from Contrast Modulation)

Discussion on the measurement techniques started last Fall as Samsung thought the standard was being misused by LG to claim that its RGBW subpixel rendering technique, which is used in some of its LCD TVs, met the criteria for a UHD-4K display. An ICDM meeting in Boulder, Colorado, in February, continued this discussion with more than a day devoted to presentations, demonstrations and detailed discussion of the measurement techniques.

The concern was that the technique of displaying one pixel-wide grid (grille) patterns and using the differences between the bright and dark levels to determine contrast and pixel resolution may work fine when the pixel is a conventional RGB stripe type, but when other pixel architectures are considered, results can vary widely based upon the measurement techniques employed.

After the Boulder meeting, several new paragraphs and a 3-4 page section with details on the proper measurement techniques and pitfalls to avoid were put forth and considered by committee members. Ultimately, the measurement technique clarifications were adopted as well as some language suggesting caution when using these techniques. It was also noted that further clarification and even modifications will be forthcoming in version 2, whose time frame remains undetermined.

At the SID meeting, the changes were adopted, but not without some dissent. Most of this centered on a vote that allowed these changes to be considered “editorial” in nature, thus avoiding a much more rigorous approval process that would have stretched out the approval process for 6-10 months.

The official versions of these three document updates, along with a revision history stating the changes for each section, are posted and available on the ICDM public web page for updates at

This topic, along with many more on HDR, WCG, contrast, transparent and 3D display metrology and much more is all being considered by ICDM as these are urgent industry needs. A review of these activities will be given by ICDM chairman, Joe Miseli at the upcoming Display Summit event. – CC