When the wavelength is increased from violet to red, the luminosity

The human eye is sensitive to light in the visible spectrum, which ranges from approximately $400\text{ nm}$ (violet) to $700\text{ nm}$ (red).

The sensitivity or luminosity of the human eye is not uniform across this range. It is maximum for yellow-green light, which has a wavelength of about $555\text{ nm}$.

Therefore, as the wavelength of light is increased from violet to red, the luminosity of the eye first increases, reaches a maximum at $555\text{ nm}$, and then decreases.