A color gamut conversion method, a color gamut converter, a display device, an image signal conversion method, a computer device and a non-transitory storage medium are disclosed. The method includes: acquiring RGB signals and a preset grayscale value of a white subpixel in each pixel of a converted image according to grayscale values of monochromatic subpixels in each pixel of an original image corresponding to the RGB signals, the converted image is obtained by converting the original image from an RGB gamut to an RGBW gamut; and acquiring a target grayscale value of the white subpixel at least according to a first maximum grayscale of the white subpixels and the preset grayscale. As for a first saturation color patch in the original image, a first maximum grayscale of a white subpixel corresponding to each pixel in the first saturation color patch is equal to a grayscale threshold.