Impact of Color and Polarity on Visual Resolution with Varying Contrast Ratios and Different Text Backgrounds.

Purpose: To assess the impact of color and polarity in predicting the changes of visual resolution for different text backgrounds with increasing contrast ratios.

Methods: Text-background designs of eight contrast ratios (0.15, 0.30, 0.47, 0.52, 0.57, 0.60, 0.70, and 0.78) and two text polarities (positive; black text and negative; white text) were compared with and without the presence of background color (blue, green, orange, and red). The visual resolution was measured in logMAR using Landolt C. The rate of changes in visual resolution measurements was analyzed using linear regression as contrast ratios increased with and without background color.

Results: Visual resolution varied significantly with and without the background color element under both polarity investigations ( 0.05). Contrast ratio accounts for 77.4% of the variation within the visual resolution measurement with a color background [F = 20.76, 0.01]. Contrast ratio accounts for 97.16% of the variation in visual resolution measurements without a color background [F = 205.63, 0.01].

Conclusion: As contrast decreases, color plays a more significant role than the non-color factor in the resolution of fine details in both polarities as it influences the visual resolution outcome which is reflected in the measurements in logMAR units.