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#1 Posted : Saturday, October 12, 2013 11:40:15 AM(UTC)

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If you have experience with preparing designs for commercial printing in Photoshop, probably you are familiar with spot channels. Spot channels are used to print additional colors on print products and they are actually channels for additional inks.

Suppose, you want to write an algorithm using Graphics Mill which stores a spot channel in a TIFF file. It can be easily done using, so called, extra channels. You just need to add a channel defining ink intensity for each pixel on the product. The only problem you encounter with is that there is no way to define what color the spot channel should be of. We dug a little bit into that and found out that color information is stored in Adobe image resource blocks in TIFF files.

The color information of a spot channel is saved in a structure having the following format:

    struct DisplayInfo
        public UInt16 colorSpace;
        public Color color;
        public UInt16 opacity;
        public byte mode;

    struct Color
        public UInt16 r;
        public UInt16 g;
        public UInt16 b;
        public UInt16 padding;

    enum ColorSpace
        RGB = 0,
        HSB = 1,
        CMYK = 2,
        LAB = 7,
        Grayscale = 8

This structure is serialized in binary format and added to Adobe image resource blocks by ID =1077. The attached sample application illustrates this concept.

Edited by user Saturday, October 12, 2013 11:42:23 AM(UTC)  | Reason: Not specified

File Attachment(s):
GM.Tiff.Sample.zip (5kb) downloaded 299 time(s).
Dmitry attached the following image(s):
Sincerely yours,
Dmitry Sevostyanov

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