A projector for projecting an image light beam according to an image signal, comprising: a receiver configured to: receive the image signal and decode the image signal to obtain a metadata of the image signal, wherein the metadata indicates an electro-optical transfer function corresponding to the image signal; determine, according to the metadata, whether the image signal is a HLG-HDR signal; and convert, if the image signal is the HLG-HDR signal, a color space of the image signal from a wider color gamut to a narrower color gamut so as to generate a converted image signal; a processor coupled to the receiver and configured to: receive the converted signal related to the image signal from the receiver and determine whether to force a color setting of the converted signal; if the processor determines to force the color setting of the converted signal, select a HLG-HDR gamma curve from a plurality of gamma curves, and perform, on the converted image signal, a gamma correction according to the HLG-HDR gamma curve, so as to generate a corrected image signal; otherwise, select a SDR gamma curve from a plurality of gamma curves, and perform, on the converted image signal, a gamma correction according to the SDR gamma curve, so as to generate a corrected image signal; and transfer the corrected image signal into an optical signal; a light source module coupled to the processor and providing a light beam; a color conversion module coupled to the processor and disposed on a transmission path of the light beam, wherein the color conversion is configured to modulate, according to the optical signal, the light beam to an illumination beam (LB'); a light valve coupled to the processor and disposed on a transmission path of the illumination beam (LB'), wherein the light valve is configured to modulate, according to the optical signal, the illumination beam (LB') to form the image light beam; and a projection lens, disposed on a transmission path of the image light beam and projecting the image light beam. a receiver configured to: receive the image signal and decode the image signal to obtain a metadata of the image signal, wherein the metadata indicates an electro-optical transfer function corresponding to the image signal; determine, according to the metadata, whether the image signal is a HLG-HDR signal; and convert, if the image signal is the HLG-HDR signal, a color space of the image signal from a wider color gamut to a narrower color gamut so as to generate a converted image signal; receive the image signal and decode the image signal to obtain a metadata of the image signal, wherein the metadata indicates an electro-optical transfer function corresponding to the image signal; determine, according to the metadata, whether the image signal is a HLG-HDR signal; and convert, if the image signal is the HLG-HDR signal, a color space of the image signal from a wider color gamut to a narrower color gamut so as to generate a converted image signal; a processor coupled to the receiver and configured to: receive the converted signal related to the image signal from the receiver and determine whether to force a color setting of the converted signal; if the processor determines to force the color setting of the converted signal, select a HLG-HDR gamma curve from a plurality of gamma curves, and perform, on the converted image signal, a gamma correction according to the HLG-HDR gamma curve, so as to generate a corrected image signal; otherwise, select a SDR gamma curve from a plurality of gamma curves, and perform, on the converted image signal, a gamma correction according to the SDR gamma curve, so as to generate a corrected image signal; and transfer the corrected image signal into an optical signal; receive the converted signal related to the image signal from the receiver and determine whether to force a color setting of the converted signal; if the processor determines to force the color setting of the converted signal, select a HLG-HDR gamma curve from a plurality of gamma curves, and perform, on the converted image signal, a gamma correction according to the HLG-HDR gamma curve, so as to generate a corrected image signal; otherwise, select a SDR gamma curve from a plurality of gamma curves, and perform, on the converted image signal, a gamma correction according to the SDR gamma curve, so as to generate a corrected image signal; and transfer the corrected image signal into an optical signal; a light source module coupled to the processor and providing a light beam; a color conversion module coupled to the processor and disposed on a transmission path of the light beam, wherein the color conversion is configured to modulate, according to the optical signal, the light beam to an illumination beam (LB'); a light valve coupled to the processor and disposed on a transmission path of the illumination beam (LB'), wherein the light valve is configured to modulate, according to the optical signal, the illumination beam (LB') to form the image light beam; and a projection lens, disposed on a transmission path of the image light beam and projecting the image light beam.