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Zoom or page resampling can blend the ordered pixels before they reach the display. The tool reports the browser’s backing-pixel scale as a warning, but it cannot determine your exact operating-system scaling configuration.
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A visual tone-response comparison
Gamma Test for Screen Tone Response
This gamma test places calculated solid greys beside ordered black-and-white pixel patterns for target exponents 1.8, 2.0, 2.2, and 2.4. At a sufficient viewing distance the fine pattern should fuse visually, allowing a cautious comparison of mid-tone response under your current browser, operating-system, and display conditions.
What you are matching
How the gamma test pattern works
A display’s tone response describes how an encoded channel value relates to visible light output. For a simple power-law target, the solid code that corresponds to a linear-light fraction L is calculated as 255 × L1/γ. The gamma test uses that equation for neutral RGB values.
Each row pairs the calculated solid grey with a two-by-two ordered pattern containing 25%, 50%, or 75% white pixels. From far enough away, those tiny pixels blend into an average. When both halves look close, the current visual response is broadly consistent with that target at that level. This is a visual match with several uncertainties, not a certified gamma measurement.
Keep the pixel pattern intact
Set up the gamma test before comparing
Move back to visual fusion
Sit centered and increase viewing distance until the patterned half no longer looks like a checker. Do not blur your eyes aggressively; use a stable, comfortable position and compare the three rows.
Hold processing constant
Keep picture mode, local contrast, HDR or SDR state, brightness, and room illumination unchanged. If you compare a second mode, record it as a separate gamma test observation.
A transparent calculation
Gamma test codes for the neutral 50% fusion reference
These are source values used by the renderer for the 50% row, not measured screen output.
| Target reference | Calculated solid RGB code | Patterned comparison |
|---|---|---|
| Gamma 1.8 | RGB 174, 174, 174 | Equal black and white backing pixels in a fixed ordered layout |
| Gamma 2.0 | RGB 180, 180, 180 | Equal black and white backing pixels in a fixed ordered layout |
| Gamma 2.2 | RGB 186, 186, 186 | Equal black and white backing pixels in a fixed ordered layout |
| Gamma 2.4 | RGB 191, 191, 191 | Equal black and white backing pixels in a fixed ordered layout |
Interpret gently
What an apparent gamma match can and cannot say
A useful visual observation
If the solid and ordered halves blend closely across the three rows for one target, you can say that target looks closest under the tested conditions. Repeat the gamma test after your eyes adapt and check whether the same target remains the best visual match.
Not an exact display result
Do not report the selected gamma test target as a measured exponent. Real transfer functions can depart from a simple power law, and a match at one or three levels does not describe the entire curve, channel balance, black level, luminance, or calibration accuracy.