Interactive three-dimensional (3D) color histograms
Techniques for interactively determining/visualizing the color content of a source image and how the corresponding image data is mapped to device colors are described herein. For example, the color content of a digital image can be converted between different color spaces to identify gamut limitations of an output device (e.g., a printing assembly), discover color(s) that cannot be accurately reproduced, etc. Color space conversions enable the transformation of the color content of the digital image from device-specific colorants to a device-independent representation (and vice versa). In some embodiments, these transformations are facilitated using lookup tables that are implemented in graphical processing unit-resident memory.
1. A method of visualizing color content resulting from printing an image, the method comprising:
acquiring a first image in a first color space;
transforming the first color space to a second color space to produce a second image from the first image;
transforming the second color space to a printer-specific color space to produce a third image from the second image;
transforming the printer-specific color space to the second color space to produce a fourth image from the third image;
binning a range of color values in the fourth image by
dividing the second color space into a series of bins that represent unique color values, and
establishing a count for each bin by counting occurrences of each unique color value in the fourth image;
creating a three-dimensional (3D) histogram that represents distribution of the range of color values across the fourth image; and
identifying gamut limitations, if any, of a printer by comparing a range of color values across the first image to the range of color values across the fourth image,
wherein each gamut limitation corresponds to a color that is included in the range of color values across the first image but is not included in the range of color values across the fourth image.
2. The method of claim 1 , wherein the first color space is a Red Green Blue (RGB) color space, and wherein the second color space is a Lab color space that is printer independent.
3. The method of claim 1 , wherein the printer-specific color space corresponds to Hi-Fi printing techniques that expand tonal range of printed images by augmenting Cyan Magenta Yellow Black (CMYK) inks with additional inks.
4. The method of claim 3 , wherein the printer-specific color space is a Cyan Magenta Yellow Black Orange Green Violet (CMYKOGV) color space.
5. The method of claim 1 , wherein the gamut limitations represent one or more colors in the first image that cannot be accurately recreated by the printer.
6. The method of claim 1 , wherein each transformation is facilitated using a multi-dimensional lookup table.
7. The method of claim 1 , further comprising:
binning the range of color values in the first image by
dividing the first color space into a series of bins that represent unique color values, and
establishing a count for each bin by counting occurrences of each color value in the first image;
creating a 3D histogram that represents distribution of the range of color values across the first image; and
allowing a user to readily discover whether any colors are being clipped by comparing the 3D histogram of color values across the first image to the 3D histogram of color values across the fourth image.