When objects travel near the speed of light, general relativity dictates that they experience time dilation, length contraction, and an increase in relativistic mass. These effects all have a magnitude equal to the Lorentz factor, which is given the Greek letter symbol gamma and is equal to:

γ = 1 / √(1 - v²/c²)

where v is the object's velocity and c is the speed of light. So as your speed increase, your relativistic gamma increases.

In image processing theory, the relationship between the brightness encoding levels and the actual displayed luminance values is frequently non-linear, being a power law with an exponent known as gamma. When a digital image is prepared on one display device, and then displayed on a device with a different gamma, the brightness levels can look wrong - a fact that leads to concern about gamma correction when preparing images for specific display devices. As the gamma of an image is increased, it appears brighter and more washed out.

Yes, to understand this joke you need to know relativity and image processing theory. No, I am unrepentant.