Halftoning is taking an image that uses continuous tones and creating one suitable for printing using one color of ink (grayscale) or four colors of ink (color printing using the Cyan, Magenta, Yellow and Black process colors). In the CMYK colored print process four separations (also called screens) are made, one for each process color. Different sizes of the dots of ink are used to produce the different levels of color. These dots are not large enough to be seen without magnification. After different adjustments are made to the separations, the article being printed goes through a process where each color gets printed in succession, one on top of the other. To prevent moiré patterns, each screen is set to a different angle.
In digital printing, generally the dot size remains constant (instead of varying). Instead the dots are broken up into small halftone cells, and the different color values are created by varying the number of the small halftone cells that take color.
LEADTOOLS provides a number of commands for working with color images and changing them so they are suitable for printing using halftoning techniques.
Color Images
Use the Leadtools.ImageProcessing.Color.ColorSeparateCommand command to separate the specified image by color plane to produce one grayscale image per plane. Note that in addition to the CYMK color space used by CYMK process printing, this command also supports the RGB, CMY, HSV, and HLS color-space models.
For an example, refer to http://www.leadtools.com/help/LEADTOOLS/v16/Main/Main%20Images/Dllsteps/ColorSeparate.htm.
Use the Leadtools.ImageProcessing.Color.ColorMergeCommand command to create a color image by merging grayscale images that were created as color separations. You can use this to recombine the images that the Leadtools.ImageProcessing.Color.ColorSeparateCommand command creates.
Use the Leadtools.ImageProcessing.Effects.ColorHalftoneCommand command to divide the image into rectangles and replace each rectangle with circles. Each channel has a separate grid of circles, and has its own angle setting. The size of each circle is proportional to the brightness of the rectangle which it is replacing. Note that with this command, the circles are large enough to be individually seen.
For an example, refer to
Halftones
Use the Leadtools.ImageProcessing.Color.DesaturateCommand to convert an image to a grayscale level by reducing the saturation of each color to zero. The conversion will not change the color resolution.
Use the Leadtools.ImageProcessing.Core.HalfToneCommand command to convert a 1-, 4-, 8-, 16-, 24-, or 32-bit image to a halftoned images, with a specified pattern rotation.
For an example, refer to http://www.leadtools.com/help/LEADTOOLS/v16/Main/Main%20Images/Dllsteps/Halftone.htm.
Use the Leadtools.ImageProcessing.Core.HalfTonePatternCommand command to create a halftone screen effect for an image while keeping its continuous range of tones.
For an example, refer to http://www.leadtools.com/help/LEADTOOLS/v16/Main/Main%20Images/Dllref/L_HalfTonePatternBitmap.htm.
Getting Information About Images
Use the Leadtools.ImageProcessing.Effects.StatisticsInformationCommand command to obtain statistical information about the images. This includes such information as the mean, median, standard deviation, maximum, minimum, pixel count values. Use the Leadtools.ImageProcessing.Color.HistogramCommand command to obtain an array that charts how many times each intensity level occurs in an image. This command can chart red, green, and blue separately or together. It is used for all resolutions, including 12 and 16-bit grayscale. Use the Leadtools.ImageProcessing.Color.ColorCountCommand command to get the number of unique colors in an image. Use the Leadtools.RasterImage.GetPaintColors command to get the palette from the image. Use the Leadtools.ImageProcessing.Core.MinMaxBitsCommand command to obtain the low and high bits of the values present in a 12 or 16-bit grayscale and 48 and 64-bit image. Use the Leadtools.ImageProcessing.Core.MinMaxValuesCommand command to obtain the minimum and maximum intensity values present in a 12 or 16-bit grayscale and 48 and 64-bit image. Please note that support for 12 and 16-bit grayscale images is only available in Document/Medical toolkits.
Grayscale Images
LEADTOOLS provides a number of commands designed specifically for use with grayscale images, either creating a grayscale image, getting information about a grayscale image, or window leveling. For more information about these commands, refer to Grayscale Images.