Appendix D
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+ Zint Barcode Generator + |
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An obvious next step in the development of barcodes is to use +colour instead of boring old black and white to encode data. This +technique is not currently used by any barcode encoding standards in +the wild but an indication of how it might be achieved can be gained +with a little data processing and the Zint library.
+This example takes an input string and splits it into +three roughly equal length strings each of which is encoded and then +combined to make a colour version of the symbol. This can then be +decoded by applying red, green and blue filters to the resulting +image and then decoding them using the same algorithm used to decode +normal black and white symbols as shown below.
+
One advantage of this system is that finder patterns in the symbol +show up clearly as black-on-white and so can be found using the +methods already established for standard 2D barcodes. This can be +clearly seen in the examples below.
+
Another advantage of this system is that it fits three times as +much data into a symbol of a given size. Disadvantages are likely to +become apparent when trying to decode these symbols in real-world +applications: decoding will require larger processor overheads and +more sophisticated algorithms. Telling white from yellow may be a +particular problem.
+The code below performs the encoding as done on the images above +and outputs an array of elements as characters representing colours. +Putting this together as an image requires additional code.
+#include <stdio.h>
+#include <zint.h>
+#include <string.h>
+
+int main(int argc, char **argv)
+{
+ struct zint_symbol *red_symbol;
+ struct zint_symbol *green_symbol;
+ struct zint_symbol *blue_symbol;
+ struct zint_symbol *colour_symbol;
+
+ int error = 0;
+ int i, j;
+ int input_len = strlen(argv[1]);
+ int snippet = input_len / 3;
+ char full_string[input_len + 5];
+ char red_string[(input_len / 3) + 2];
+ char green_string[(input_len / 3) + 2];
+ char blue_string[(input_len / 3) + 2];
+ int symbol_type = BARCODE_QRCODE;
+
+ if(input_len % 3 != 0) { snippet++; }
+ strcpy(full_string, argv[1]);
+
+ for(i = 0; i < snippet; i++) {
+ red_string[i] = full_string[i];
+ green_string[i] = full_string[i + snippet];
+ blue_string[i] = full_string[i + snippet + snippet];
+ }
+ red_string[i] = '\0';
+ green_string[i] = '\0';
+ blue_string[i] = '\0';
+
+ red_symbol = ZBarcode_Create();
+ green_symbol = ZBarcode_Create();
+ blue_symbol = ZBarcode_Create();
+ colour_symbol = ZBarcode_Create();
+
+ red_symbol->symbology = symbol_type;
+ green_symbol->symbology = symbol_type;
+ blue_symbol->symbology = symbol_type;
+ colour_symbol->symbology = symbol_type;
+
+ error = ZBarcode_Encode(red_symbol, (unsigned char *)red_string);
+ error += ZBarcode_Encode(green_symbol, (unsigned char *)green_string);
+ error += ZBarcode_Encode(blue_symbol, (unsigned char *)blue_string);
+
+ if(error != 0) {
+ printf("Some error occurred!\n");
+ ZBarcode_Delete(red_symbol);
+ ZBarcode_Delete(green_symbol);
+ ZBarcode_Delete(blue_symbol);
+ ZBarcode_Delete(colour_symbol);
+ return 1;
+ }
+
+ colour_symbol->width = red_symbol->width;
+ if(green_symbol->width > colour_symbol->width) { colour_symbol->width = green_symbol->width; }
+ if(blue_symbol->width > colour_symbol->width) { colour_symbol->width = blue_symbol->width; }
+
+ colour_symbol->rows = red_symbol->rows;
+ if(green_symbol->rows > colour_symbol->rows) { colour_symbol->rows = green_symbol->rows; }
+ if(blue_symbol->rows > colour_symbol->rows) { colour_symbol->rows = blue_symbol->rows; }
+
+ for(i = 0; i < colour_symbol->rows; i++) {
+ colour_symbol->row_height[i] = 1;
+ for(j = 0; j < colour_symbol->width; j++) {
+ int colourval;
+
+ colourval = 0;
+
+ if(red_symbol->encoded_data[i][j] == '1') { colourval += 4; }
+ if(green_symbol->encoded_data[i][j] == '1') { colourval += 2; }
+ if(blue_symbol->encoded_data[i][j] == '1') { colourval += 1; }
+
+ switch(colourval) {
+ case 0: colour_symbol->encoded_data[i][j] = '0'; break; /* white */
+ case 1: colour_symbol->encoded_data[i][j] = 'Y'; break; /* yellow */
+ case 2: colour_symbol->encoded_data[i][j] = 'M'; break; /* magenta */
+ case 3: colour_symbol->encoded_data[i][j] = 'R'; break; /* red */
+ case 4: colour_symbol->encoded_data[i][j] = 'C'; break; /* cyan */
+ case 5: colour_symbol->encoded_data[i][j] = 'G'; break; /* green */
+ case 6: colour_symbol->encoded_data[i][j] = 'B'; break; /* blue */
+ case 7: colour_symbol->encoded_data[i][j] = '1'; break; /* black */
+ }
+ printf("%c",colour_symbol->encoded_data[i][j]);
+ }
+ printf("\n");
+ }
+
+ ZBarcode_Delete(red_symbol);
+ ZBarcode_Delete(green_symbol);
+ ZBarcode_Delete(blue_symbol);
+ ZBarcode_Delete(colour_symbol);
+ return 0;
+}+
| + + | ++ + | ++ | +
|
+ Appendix C + |
+
+ + |
+ + | +