Method of digital processing for digital cinema projection of tone scale and color

A method for processing a sequence of digital image signals in order to match the appearance of a particular display medium when the image signals are displayed on a display device, said method comprising the steps of:

• providing the sequence of digital image signals;
• converting the digital image signals into signal values in an analytical dye amount space where the signal values are proportional to a dye set corresponding to the particular medium,
• converting the signal values in analytical dye amount space into signals in a perceptual color space based upon a chosen illuminant for display of the image signals;
• converting the signals in the perceptual color space into output values suitable for a display device;
• re-mapping any output values that are out of the gamut of the display device into re-mapped output values;
• and
• providing the output values, including any re-mapped values, to the display device.

A method for processing a sequence of digital image signals in order to match the tone scale and color of a particular motion picture print film when the image signals are digitally projected, said method comprising the steps of:

• scanning motion picture film to provide the sequence of digital image signals;
• converting the image signals into signal values in an analytical dye amount space where the signal values are proportional to a dye set corresponding to the particular motion picture print film;
• converting the signal values in analytical dye amount space into signals in a perceptual color space based upon a chosen illuminant for display of the image signals;
• converting the signals in the perceptual color space into output values suitable for a digital projector;
• re-mapping any output values that are out of the gamut of the digital projector;
• and
• providing the re-mapped values to the display device.

A method for re-mapping out of gamut colors into a display device color space, said method comprising the steps of:

• determining a maximum color gamut of the display device in a perceptual color space that represents the combination of hue, lightness and saturation;
• determining if a target color is out of gamut for the display device, thereby providing an out of gamut target color;
• obtaining a hue angle for the out of gamut target color;
• using the hue angle, determining the lightness value of the out of gamut target color;
• and
• holding the hue angle constant, altering the lightness and saturation, as necessary to bring the out of gamut target color into the display device color space.