You must have heard people saying this bulb is “xW;” the larger this value is, the brighter this bulb will be. The term watt refers to the power of a bulb; the larger the watt value is, the more power this bulb will consume. Lumen is the unit of luminous flux, a measure of the power of light. From the same distance, a higher lumen brings more brightness. On the contrary, with the same lumen, the shorter projection distance is, the brighter the screen will be; a larger screen requires a larger lumen. But you need to be aware that viewing a too bright screen for a long time would damage your eyes.
When choosing a TV, desktop monitor or projector, we usually compare the “contrast ratio.” Contrast ratio is the value measured by the equipment when dividing the brightness between the darkest and the brightest still images. The higher the contrast ratio is, a more saturated color and sharper image will be displayed. Meanwhile, “dynamic contrast” claimed by some products refers to the feature that decreases the black level instantly to maximize the black and white contrast when playing dark images. The gained dynamic contrast ratio is usually 3 to 5 times higher than the static contrast ratio. So consumers must consider their purposes carefully before selecting a project.