Why does a gamma test look different when I enable HiDPI?

A gamma test made from fine alternating lines depends on how those lines reach the panel’s pixels. HiDPI rendering, image resizing and fractional scaling can change the pattern itself. The test can therefore look different even when the monitor’s gamma is unchanged.

The macOS scaling explanation compares fractional scaling and pixel mapping.

For a pixel-pattern comparison, use the panel’s native-resolution LoDPI mode and display the test image without resizing it. Check browser or image-viewer zoom as well. Each image pixel needs to match one physical display pixel. The resolution label alone cannot confirm that match. Keep the monitor’s picture settings, HDR state and color profile unchanged while comparing.

Browser color management also affects web tests, as the EIZO monitor test explains. A screenshot viewed at another size or on another device adds another rendering path and cannot establish the original panel’s gamma.

Do not adjust gamma solely to make a resampled line pattern agree with its reference. If ordinary images still show crushed highlights or washed-out colors, investigate that separately. See output-range mismatches and text clarity after enabling HiDPI. A precise calibration requires measurements. This visual comparison only helps separate a scaling artifact from another color problem.