A projection system , comprising: a signal processor configured to receive image data comprising a plurality of grayscale values, each of which corresponds to one pixel, wherein the signal processor is further configured to increase grayscale values of a plurality of pixels of the image data; an adjusting member configured to reduce luminous flux of illumination light provided to a Digital Micro-mirror Device (DMD) when the grayscale values of the image data are increased, wherein the DMD is configured to modulate the illumination light with the reduced luminous flux according to the image data with the increased grayscale values, to generate projection light required for projecting the image data; a light source module configured to emit illumination light and a light homogenizing member configured to homogenize the illumination light, wherein the adjusting member is located between the light source module and the light homogenizing member ; characterized in that : the adjusting member comprises a liquid crystal lens; and the liquid crystal lens is configured to reduce a divergence angle of the illumination light under driving of a driving member , so that a cross sectional area of the illumination light, when being incident to an incident surface of the light homogenizing member is larger than an area of the incident surface, such that the illumination light has reduced luminous flux. a signal processor configured to receive image data comprising a plurality of grayscale values, each of which corresponds to one pixel, wherein the signal processor is further configured to increase grayscale values of a plurality of pixels of the image data; an adjusting member configured to reduce luminous flux of illumination light provided to a Digital Micro-mirror Device (DMD) when the grayscale values of the image data are increased, wherein the DMD is configured to modulate the illumination light with the reduced luminous flux according to the image data with the increased grayscale values, to generate projection light required for projecting the image data; a light source module configured to emit illumination light and a light homogenizing member configured to homogenize the illumination light, wherein the adjusting member is located between the light source module and the light homogenizing member ; characterized in that : the adjusting member comprises a liquid crystal lens; and the liquid crystal lens is configured to reduce a divergence angle of the illumination light under driving of a driving member , so that a cross sectional area of the illumination light, when being incident to an incident surface of the light homogenizing member is larger than an area of the incident surface, such that the illumination light has reduced luminous flux. the adjusting member comprises a liquid crystal lens; and the liquid crystal lens is configured to reduce a divergence angle of the illumination light under driving of a driving member , so that a cross sectional area of the illumination light, when being incident to an incident surface of the light homogenizing member is larger than an area of the incident surface, such that the illumination light has reduced luminous flux. <EOS>