Head-up display for a motor vehicle, said head-up display comprising: - a first image-generating unit controlled by a computer for generating first images, - a second image-generating unit, distinct from the first image-generating unit and controlled by a computer for generating second images, and - an image-projecting optical assembly, which is configured to concomitantly project the first and second images (Img1, Img2) into the field of view of the driver of the motor vehicle and which comprises a partially reflective mirror, on either side of which are placed the first and second image-generating units (11, 12), wherein said mirror is a spectrally selective optical filter configured to predominantly reflect light at least at a first wavelength (λ 1), and to predominantly transmit light at least at a second wavelength (λ 4)distinct from said first wavelength (λ 1), and wherein: - the first image-generating unit comprises at least one monochromatic light source, which emits only at said first or said second wavelength (λ 1, λ 4), respectively, - the second image-generating unit is configured to generate a light beam in a wavelength band (Δλ) that contains said second or said first wavelength (λ 1, λ 4), respectively, and - said spectrally selective optical filter is configured to transmit or reflect, respectively, light in most of said wavelength band (Δλ), and wherein said first image-generating unit is a laser scanner that comprises at least one laser diode emitting a wavelength (λ 1, λ 4) comprised in the wavelength band (Δλ). - a first image-generating unit controlled by a computer for generating first images, - a second image-generating unit, distinct from the first image-generating unit and controlled by a computer for generating second images, and - an image-projecting optical assembly, which is configured to concomitantly project the first and second images (Img1, Img2) into the field of view of the driver of the motor vehicle and which comprises a partially reflective mirror, on either side of which are placed the first and second image-generating units (11, 12), wherein said mirror is a spectrally selective optical filter configured to predominantly reflect light at least at a first wavelength (λ 1), and to predominantly transmit light at least at a second wavelength (λ 4)distinct from said first wavelength (λ 1), and wherein: - the first image-generating unit comprises at least one monochromatic light source, which emits only at said first or said second wavelength (λ 1, λ 4), respectively, - the second image-generating unit is configured to generate a light beam in a wavelength band (Δλ) that contains said second or said first wavelength (λ 1, λ 4), respectively, and - said spectrally selective optical filter is configured to transmit or reflect, respectively, light in most of said wavelength band (Δλ), - the first image-generating unit comprises at least one monochromatic light source, which emits only at said first or said second wavelength (λ 1, λ 4), respectively, - the second image-generating unit is configured to generate a light beam in a wavelength band (Δλ) that contains said second or said first wavelength (λ 1, λ 4), respectively, and - said spectrally selective optical filter is configured to transmit or reflect, respectively, light in most of said wavelength band (Δλ),