Fig 1.
Images of the same case under each image quality setting.
Yellow–Blue is the channel value, and as the blue value decreases, the yellow value increases. Saturation represents the vividness of the color. The following channels were compared in each captured image: Normal [Yellow–Blue 94, Saturation 90]; Monochrome-0 [Yellow–Blue 0, Saturation 0]; and Monochrome-20 [Yellow–Blue 0, Saturation 20].
Fig 2.
The relationship between each color tone and contrast ratio.
A comparison of the contrast ratio between the Brilliant Blue G (BBG)-stained internal limiting membrane (ILM) and ILM-peeled area was conducted among the three-color tones. The contrast ratios were 1.62 ± 0.15 in the Normal group, 2.05 ± 0.44 in the Monochrome-0 group, and 2.00 ± 0.51 in the Monochrome-20 group. The contrast ratios were significantly higher in the Monochrome-0 and Monochrome-20 groups than in the Normal group (p < 0.01 for both), while no significant difference was observed between the Monochrome-0 and Monochrome-20 groups (p = 0.554).
Fig 3.
By increasing the saturation, the contrast ratio between hemorrhagic and non-hemorrhagic areas was higher in the Monochrome-20 group than in the Monochrome-0 group. Thus, the use of color facilitated the distinction of the hemorrhagic area, compared with the use of the completely monochromatic mode.
Fig 4.
Color component values of the hemorrhagic and non-hemorrhagic areas were substituted into a conversion formula for brightness, called the hue, saturation, brightness (HSB) conversion formula.
When the hemorrhagic area was converted to brightness only in the Normal mode, the brightness was 27.4%, whereas that of the non-hemorrhagic area was 29.8%. In other words, the difference in brightness between hemorrhagic and non-hemorrhagic areas in the Monochrome 0 mode, where saturation is 0, is small.