Purpose

Typical Usage

pdfsizeopt --use-pngout=NO --use-jbig2=NO --use-sam2p-pr=NO \
--use-image-optimizer="convert %(sourcefnq)s pbm:- | scan-filter | convert pbm:- %(targetfnq)s" \
document.pdf

Source Code

The following source code can be compiled with any standard C compilers.

  1 #include <stdio.h>
  2 #include <stdlib.h>
  3 #include <string.h>
  4 
  5 static size_t bytes_of_row;
  6 static size_t width, height;
  7 static char *buf;
  8 
  9 char get_pixel(int row, int col)
 10 {
 11     const unsigned char byte = buf[row * bytes_of_row + col / 8];
 12     return (byte & (1 << (7-col%8))) ? 1 : 0;
 13 }
 14 
 15 void set_pixel(int row, int col, char val)
 16 {
 17     const size_t byte_index = row * bytes_of_row + col / 8;
 18     const unsigned char byte_mask = 1 << (7-col%8);
 19     if (val) {
 20         buf[byte_index] |= byte_mask;
 21     } else {
 22         buf[byte_index] &= ~byte_mask;
 23     }
 24 }
 25 
 26 void read_image()
 27 {
 28     char magic[10];
 29     scanf("%9s", magic);
 30     if (strcmp(magic, "P4")){
 31         puts("Only the binary pbm is implemented");
 32         exit(2);
 33     }
 34     scanf("%lu%lu", &width, &height);
 35     getchar();
 36     bytes_of_row = (width+7) / 8;
 37     buf = calloc(bytes_of_row, height);
 38     if (fread(buf, bytes_of_row, height, stdin) != height) {
 39         puts("Not enough pixels in the image");
 40         exit(3);
 41     }
 42     if (getchar() != EOF) {
 43         puts("Only one image per file is supported or too much data");
 44         exit(4);
 45     }
 46 }
 47 
 48 size_t filter_dots()
 49 {
 50     size_t row, col;
 51     int counter = 0;
 52     for (row = 1; row < height-1; ++row) {
 53         for (col = 1; col < width-1; ++col) {
 54             if ( get_pixel(row, col) == 1 &&
 55                  get_pixel(row-1, col-1) +
 56                  get_pixel(row-1, col)*2 +
 57                  get_pixel(row-1, col+1) +
 58                  get_pixel(row, col-1)*2 +
 59                  get_pixel(row, col+1)*2 +
 60                  get_pixel(row+1, col-1) +
 61                  get_pixel(row+1, col)*2 +
 62                  get_pixel(row+1, col+1) <= 1
 63                ) {
 64                 set_pixel(row, col, 0);
 65                 ++counter;
 66             }
 67         }
 68     }
 69     fprintf(stderr, "Removed black dot: %d\n", counter);
 70     return counter;
 71 }
 72 
 73 size_t fill_white()
 74 {
 75     size_t row, col;
 76     int counter = 0;
 77     for (row = 1; row < height-1; ++row) {
 78         for (col = 1; col < width-1; ++col) {
 79             if ( get_pixel(row, col)   == 0 &&
 80                  get_pixel(row-1, col-1) +
 81                  get_pixel(row-1, col)*2 +
 82                  get_pixel(row-1, col+1) +
 83                  get_pixel(row, col-1)*2 +
 84                  get_pixel(row, col+1)*2 +
 85                  get_pixel(row+1, col-1) +
 86                  get_pixel(row+1, col)*2 +
 87                  get_pixel(row+1, col+1) >= 8
 88             ) {
 89                 set_pixel(row, col, 1);
 90                 ++counter;
 91             }
 92         }
 93     }
 94     fprintf(stderr, "Filled white dot: %d\n", counter);
 95     return counter;
 96 }
 97 
 98 
 99 void write_image()
100 {
101     printf("P4\n%lu %lu\n", width, height);
102     fwrite(buf, bytes_of_row, height, stdout);
103 }
104 
105 void process()
106 {
107     while (fill_white());
108     while (filter_dots());
109 }
110 
111 int main(int argc, char *argv[])
112 {
113     if (argc > 1) {
114         printf("Usage: %s\n It consumes a pbm from the standard input.", argv[0]);
115         return 1;
116     }
117     read_image();
118     process();
119     write_image();
120     return 0;
121 }

Known Issue With pdfsizeopt

    def CompareObjInfo(a, b):
        # Instead of the original comparison:
        return -1
        # The original comparison:
        # Compare first by byte size, then by command name.
        # return a[0].__cmp__(b[0]) or CompareStr(a[1], b[1])