PDFlib Cookbook

cookbook

images/image_color_manipulation new

Manipulate image colors with the 'decode' and 'chromakey' options.

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/*
 * Image color manipulation:
 * Manipulate image colors with the "decode" and "chromakey" options.
 *
 * Required software: PDFlib/PDFlib+PDI/PPS 9.2
 * Required data: image file
 */
package com.pdflib.cookbook.pdflib.images;

import com.pdflib.pdflib;
import com.pdflib.PDFlibException;

public class image_color_manipulation
{
    public static void main (String argv[])
    {
        /* This is where the data files are. Adjust as necessary. */
        String searchpath = "../input";
        String outfile = "image_color_manipulation.pdf";
        String title = "Image color manipulation";

        pdflib p = null;
        int exitcode = 0;
        String imagefile = "zebra.tif";
        int image;
        int x = 20, y1 = 20, y2 = 800;

        try {
            p = new pdflib();

            String testcases[][] = {
                /* image option list                     effect achieved */
                { "",                                   "original image" },
                { "decode={1 0 1 0 1 0}",               "invert image colors (same as 'invert')" },
                { "decode={-0.3 1.3 -0.3 1.3 -0.3 1.3}","increase contrast" },
                { "decode={0.1 0.9 0.1 0.9 0.1 0.9}",   "reduce contrast" },
                { "decode={0.2 1.2 0.2 1.2 0.2 1.2}",   "lighten all colors by 20%" },
                { "decode={-0.1 0.9 -0.1 0.9 -0.1 0.9}","darken all colors by 10%" },

                { "chromakey={0 77 0 77 0 77}",         "treat colors darker than 30% as transparent" },
                { "chromakey={153 255 153 255 153 255}","treat colors lighter than 60% as transparent" },                    
            };

            p.set_option("searchpath={" + searchpath + "}");

            /* This means we must check return values of load_font() etc. */
            p.set_option("errorpolicy=return");

            if (p.begin_document(outfile, "") == -1)
                throw new Exception("Error: " + p.get_errmsg());

            p.set_info("Creator", "PDFlib Cookbook");
            p.set_info("Title", title);

            for (String[] testcase: testcases)
            {
                String textopt = "fontname=NotoSerif-Regular encoding=unicode fontsize=12";

                p.begin_page_ext(0, 0, "width=a4.width height=a4.height");
                
                /* Output option list and description */
                if (testcase[0].equals(""))
                    p.fit_textline("No image option: " + testcase[1], x, y2, textopt);
                else
                    p.fit_textline("Image option '" + testcase[0] + "': " + testcase[1],
                        x, y2, textopt);
                
                /* Load the image with option */
                image = p.load_image("auto", imagefile, testcase[0]);
                if (image == -1)
                    throw new Exception("Error: " + p.get_errmsg());
                        
                p.fit_image(image, x, y1, "boxsize={540 800} fitmethod=meet");
             
                p.close_image(image);
                p.end_page_ext("");
            }

            p.end_document("");

        } catch (PDFlibException e) {
            System.err.println("PDFlib exception occurred:");
            System.err.println("[" + e.get_errnum() + "] " + e.get_apiname() +
                                ": " + e.get_errmsg());
            exitcode = 1;
        } catch (Exception e) {
            System.err.println(e);
            exitcode = 1;
        } finally {
            if (p != null) {
                p.delete();
            }
            System.exit(exitcode);
        }
    }
}