Doug Kerr
Well-known member
This is to summarize a matter that was developed over a series of messages in another thread in this section.
************
The Lacom monitor test suite, developed by Han-Kwang Nienhuys, allows us to ascertain various aspects of the behavior of our our display chain ("monitor") without need for a colorimetric instrument (such as is used in the Spyder test packages). (Thanks to Maggie Terlecki for calling this test suite to our attention.)
That test suite can be accessed here:
http://www.lagom.nl/lcd-test/
One test in the suite allows us to ascertain the "gamma" of our display chain by visual observation of a special test image.
However, with respect to the gamma test image, there is an important prerequisite for doing so, not clearly stated on the site. The gamma test image must be presented pixel-for-pixel on the screen by the browser. If not, the gamma test just does not work.
In the case of my browser, Mozilla Firefox (currently at version 30.0), attaining that requires both the following:
• The browser zoom level must be set to "normal" (or "reset"), as done with Ctrl+0.
• The system display resolution must be set to 96 DPI (100%).
Thus, if you normally operate with another display resolution setting, you essentially must make this particular test "offline", using the downloaded gamma test file and observing it through a competent viewer.
It is entirely possible that others of the Lacom tests may be subject to this same prerequisite. I have not done any analysis of those.
Best regards,
Doug
************
The Lacom monitor test suite, developed by Han-Kwang Nienhuys, allows us to ascertain various aspects of the behavior of our our display chain ("monitor") without need for a colorimetric instrument (such as is used in the Spyder test packages). (Thanks to Maggie Terlecki for calling this test suite to our attention.)
That test suite can be accessed here:
http://www.lagom.nl/lcd-test/
One test in the suite allows us to ascertain the "gamma" of our display chain by visual observation of a special test image.
This parameter characterizes the nonlinear transfer curve between RGB coordinate values and the resulting luminance on the display. It applies in a peculiar way to the transfer curve prescribed to directly support the sRGB color space.
The various test images in the Lacom suite are available for download (in a ZIP archive) from the Lacom site. They can then be observed via a competent viewer and the various conclusions drawn from what we see. But a more convenient way is to view them in your browser, working from the Lacom test procedure pages, which give detailed instructions for interpreting the images.However, with respect to the gamma test image, there is an important prerequisite for doing so, not clearly stated on the site. The gamma test image must be presented pixel-for-pixel on the screen by the browser. If not, the gamma test just does not work.
In the case of my browser, Mozilla Firefox (currently at version 30.0), attaining that requires both the following:
• The browser zoom level must be set to "normal" (or "reset"), as done with Ctrl+0.
• The system display resolution must be set to 96 DPI (100%).
Thus, if you normally operate with another display resolution setting, you essentially must make this particular test "offline", using the downloaded gamma test file and observing it through a competent viewer.
It is entirely possible that others of the Lacom tests may be subject to this same prerequisite. I have not done any analysis of those.
Best regards,
Doug