arian/ssocr
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

add option -M, --min-char-dims=WxH

Browse Source 
When there is a bit of noise in the image, the segmentation
step might find lots of small potential digits that are not
really digits (or other characters) of the display.  Given
sufficiently large display characters, it may be possible
to specify minimum character dimensions to remove spurious
potential characters (digits) based on their size.
This commit is contained in:
Erik Auerswald
2023-04-30 19:14:19 +02:00
parent 8df40937c9
commit 9e2d37ddbf
6 changed files with 157 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
NEWS
+1
View File
@@ -5,6 +5,7 @@ Upcoming Version ?.??.? (????-??-??):
-------------------------------------
* New option -N, --min-segment to specify the minimum width and height of
a segment, for both scanline based and ratio based character recognition
* New option -M, --min-char-dims to specify minimum character dimensions
Version 2.22.2 (2023-04-24):
----------------------------
defines.h
+6
View File
@@ -122,6 +122,12 @@
* used for decimal separators */
#define MIN_SEGMENT 1
/* minimum width of a character respectively digit */
#define MIN_CHAR_W 1
/* minimum height of a character respectively digit */
#define MIN_CHAR_H 1
/* ignore # of pixels when checking a column fo black or white */
#define IGNORE_PIXELS 0
help.c
+13 -10
View File
@@ -123,6 +123,7 @@ void usage(char *name, FILE *f)
fprintf(f, " -N, --min-segment=SIZE minimum width and height of a segment\n");
fprintf(f, " -i, --ignore-pixels=# number of pixels ignored when searching digit\n");
fprintf(f, " boundaries\n");
fprintf(f, " -M, --min-char-dims=WxH minimum width and height of a character/digit\n");
fprintf(f, " -d, --number-digits=# number of digits in image (-1 for auto)\n");
fprintf(f, " -r, --one-ratio=# height/width ratio to recognize a \'one\'\n");
fprintf(f, " -m, --minus-ratio=# width/height ratio to recognize a minus sign\n");
@@ -185,23 +186,25 @@ void usage(char *name, FILE *f)
fprintf(f, " pixels set (including checked position)\n");
fprintf(f, " keep_pixels_filter MASK keeps pixels that have at least MASK neighbor\n");
fprintf(f, " pixels set (not counting the checked pixel)\n");
fprintf(f, "\nDefaults: needed pixels = %2d\n", NEED_PIXELS);
fprintf(f, " minimum segment size = %2d\n", MIN_SEGMENT);
fprintf(f, " ignored pixels = %2d\n", IGNORE_PIXELS);
fprintf(f, " no. of digits = %2d\n", NUMBER_OF_DIGITS);
fprintf(f, " threshold = %5.2f\n", THRESHOLD);
fprintf(f, " foreground = %s\n",
fprintf(f, "\nDefaults: needed pixels = %2d\n", NEED_PIXELS);
fprintf(f, " minimum segment size = %2d\n", MIN_SEGMENT);
fprintf(f, " minimum character width = %2d\n", MIN_CHAR_W);
fprintf(f, " minimum character height = %2d\n", MIN_CHAR_H);
fprintf(f, " ignored pixels = %2d\n", IGNORE_PIXELS);
fprintf(f, " no. of digits = %2d\n", NUMBER_OF_DIGITS);
fprintf(f, " threshold = %5.2f\n", THRESHOLD);
fprintf(f, " foreground = %s\n",
(SSOCR_DEFAULT_FOREGROUND == SSOCR_BLACK) ? "black" : "white");
fprintf(f, " background = %s\n",
fprintf(f, " background = %s\n",
(SSOCR_DEFAULT_BACKGROUND == SSOCR_BLACK) ? "black" : "white");
fprintf(f, " luminance = ");
fprintf(f, " luminance = ");
print_lum_key(DEFAULT_LUM_FORMULA, f); fprintf(f, "\n");
fprintf(f, " height/width threshold for digit one = %2d\n", ONE_RATIO);
fprintf(f, " width/height threshold for minus sign = %2d\n", MINUS_RATIO);
fprintf(f, " max_dig_h/h threshold for decimal sep = %2d\n", DEC_H_RATIO);
fprintf(f, " max_dig_w/w threshold for decimal sep = %2d\n", DEC_W_RATIO);
fprintf(f, " space width factor = %.2f\n", SPC_FAC);
fprintf(f, " character set = ");
fprintf(f, " space width factor = %.2f\n", SPC_FAC);
fprintf(f, " character set = ");
print_cs_key(DEFAULT_CHARSET, f); fputs("\n", f);
fprintf(f, "\nOperation: The IMAGE is read, the COMMANDs are processed in the sequence\n");
fprintf(f, " they are given, in the resulting image the given number of digits\n");
ssocr.1.in
+12
View File
@@ -75,6 +75,18 @@ Can be used to ignore some noise in the picture.
See the web page of
.BR ssocr (1)
for a description of the algorithm.
.SS \-M, \-\-min\-char\-dims WIDTHxHEIGHT
Specify the minimum dimensions of characters respectively digits.
When the segmentation step finds potential digits,
those with a width less than
.B WIDTH
or a height less than
.B HEIGHT
are ignored.
Can be used to ignore some noise in the picture.
See the web page of
.BR ssocr (1)
for a description of the algorithm.
.SS \-d, \-\-number\-digits NUMBER
Specifies the number of digits shown in the image. Default value is
.IR 6 .
ssocr.c
+121 -5
View File
@@ -27,7 +27,7 @@
#include <stdlib.h> /* exit */
/* string manipulation */
#include <string.h> /* memcpy, strdup, strlen */
#include <string.h> /* memcpy, strchr, strdup, strlen */
/* option parsing */
#include <getopt.h> /* getopt */
@@ -146,6 +146,52 @@ static void print_spaces(FILE *f, int n)
}
}
/* parse dimensions given as a string in the format "WxH" */
static int parse_width_height(const char *s, dimensions_struct *d)
{
size_t l;
const char *width_string;
char *height_string;
int w, h;
if (!s || !d) {
fputs(PROG ": error: parse_width_height() called with NULL pointer\n",
stderr);
return 1;
}
l = strlen(s);
if (l == 0) {
fputs(PROG ": error: parse_width_height() called with empty string\n",
stderr);
return 1;
}
width_string = s;
height_string = strchr(s, 'x');
if (!height_string) {
fputs(PROG ": error: no 'x' in dimension specification\n", stderr);
return 1;
}
if (width_string == height_string) {
fputs(PROG ": error: width missing from dimension specification\n", stderr);
return 1;
}
height_string++;
if (strlen(height_string) == 0) {
fputs(PROG ": error: height missing from dimension specification\n",stderr);
return 1;
}
w = atoi(width_string);
h = atoi(height_string);
if (w < 1 || h < 1) {
fprintf(stderr,
PROG ": warning: ignoring mininmum character dimensions %dx%d\n",
w, h);
return 1;
}
d->w = w;
d->h = h;
return 0;
}
/*** main() ***/
int main(int argc, char **argv)
@@ -161,6 +207,7 @@ int main(int argc, char **argv)
int unknown_digit=0; /* was one of the 6 found digits an unknown one? */
int need_pixels = NEED_PIXELS; /* pixels needed to set segment in scanline */
int min_segment = MIN_SEGMENT; /* minimum pixels needed for a segment */
dimensions_struct min_char_dims; /* minimum character dimensions (W x H) */
int number_of_digits = NUMBER_OF_DIGITS; /* look for this many digits */
int potential_digits; /* number of potential digits after segmentation */
int ignore_pixels = IGNORE_PIXELS; /* pixels to ignore when checking column */
@@ -192,6 +239,10 @@ int main(int argc, char **argv)
int found_pixels=0; /* how many pixels are already found */
color_struct d_color = {0, 0, 0, 0}; /* drawing color */
/* initialize minimum character dimensions structure */
min_char_dims.w = MIN_CHAR_W;
min_char_dims.h = MIN_CHAR_H;
/* if we provided no arguments to the program exit */
if (argc < 2) {
usage(PROG, stderr);
@@ -211,6 +262,7 @@ int main(int argc, char **argv)
{"iter-threshold", 0, 0, 'T'}, /* use treshold value as provided */
{"number-pixels", 1, 0, 'n'}, /* pixels needed to regard segment as set */
{"min-segment", 1, 0, 'N'}, /* minimum pixels needed for a segment */
{"min-char-dims", 1, 0, 'M'}, /* minimum character (digit) dimensions */
{"ignore-pixels", 1, 0, 'i'}, /* pixels ignored when searching digits */
{"number-digits", 1, 0, 'd'}, /* number of digits in image */
{"one-ratio", 1, 0, 'r'}, /* height/width threshold to recognize a one */
@@ -237,7 +289,7 @@ int main(int argc, char **argv)
{0, 0, 0, 0} /* terminate long options */
};
c = getopt_long (argc, argv,
"hVt:vaTn:N:i:d:r:m:o:O:D::pPf:b:Igl:SXCc:H:W:sA:G",
"hVt:vaTn:N:i:d:r:m:M:o:O:D::pPf:b:Igl:SXCc:H:W:sA:G",
long_options, &option_index);
if (c == -1) break; /* leaves while (1) loop */
switch (c) {
@@ -305,6 +357,19 @@ int main(int argc, char **argv)
}
}
break;
case 'M':
if(optarg) {
int ret;
ret = parse_width_height(optarg, &min_char_dims);
if (ret) {
fprintf(stderr, "warning: ignoring --min-char-dims=%s\n", optarg);
}
if(flags & DEBUG_OUTPUT) {
fprintf(stderr, "min_char_dims = %dx%d\n", min_char_dims.w,
min_char_dims.h);
}
}
break;
case 'i':
if(optarg) {
ignore_pixels = atoi(optarg);
@@ -516,6 +581,7 @@ int main(int argc, char **argv)
fprintf(stderr, "flags & SPC_USE_AVG_DST=%d\n", flags & SPC_USE_AVG_DST);
fprintf(stderr, "need_pixels = %d\n", need_pixels);
fprintf(stderr, "min_segment = %d\n", min_segment);
fprintf(stderr, "min_char_dims = %dx%d\n",min_char_dims.w,min_char_dims.h);
fprintf(stderr, "ignore_pixels = %d\n", ignore_pixels);
fprintf(stderr, "number_of_digits = %d\n", number_of_digits);
fprintf(stderr, "foreground = %d (%s)\n", ssocr_foreground,
@@ -1152,6 +1218,56 @@ int main(int argc, char **argv)
}
}
}
if (flags & DEBUG_OUTPUT) {
fprintf(stderr, "image segmentation found %d potential digits\n",
potential_digits);
}
/* image has been segmented into potential digits, ignore too small ones */
if (min_char_dims.w > 1 || min_char_dims.h > 1) {
int digit_count = 0, pos;
digit_struct *tmp;
if (flags & DEBUG_OUTPUT) {
fputs("dropping too small potential digits\n", stderr);
}
/* count sufficiently large digits */
for (d = 0; d < potential_digits; d++) {
if (digits[d].x2 - digits[d].x1 >= min_char_dims.w &&
digits[d].y2 - digits[d].y1 >= min_char_dims.h) {
if (flags & DEBUG_OUTPUT) {
fprintf(stderr, " keeping sufficiently large digit %d\n", d);
}
digit_count += 1;
} else if (flags & DEBUG_OUTPUT) {
fprintf(stderr, " dropping too small potential digit %d\n", d);
}
}
if (flags & DEBUG_OUTPUT) {
fprintf(stderr, "keeping %d of %d potential digits\n", digit_count,
potential_digits);
}
/* allocate memory for sufficiently large digits */
if(!(tmp = calloc(digit_count, sizeof(digit_struct)))) {
perror(PROG ": tmp = calloc()");
exit(99);
}
/* keep only sufficiently large digits */
pos = 0;
for (d = 0; d < potential_digits; d++) {
if (digits[d].x2 - digits[d].x1 >= min_char_dims.w &&
digits[d].y2 - digits[d].y1 >= min_char_dims.h) {
if (pos >= digit_count) {
fputs(PROG ": error copying digit information", stderr);
exit(99);
}
memcpy(tmp + pos, digits + d, sizeof(digit_struct));
pos++;
}
}
free(digits);
digits = tmp;
potential_digits = digit_count;
}
/* check if expected number of digits have been found */
if ((number_of_digits > -1) && (number_of_digits != potential_digits)) {
@@ -1166,13 +1282,13 @@ int main(int argc, char **argv)
exit(1);
}
/* accept all potential characters / digits */
/* continue to work with the accepted number of characters / digits */
number_of_digits = potential_digits;
if (flags & DEBUG_OUTPUT) {
fprintf(stderr, "image segmentation found %d digits\n", number_of_digits);
}
/* draw rectangles around digits */
/* draw rectangles around accepted digits */
if(flags & USE_DEBUG_IMAGE) {
imlib_context_set_image(debug_image);
imlib_context_set_color(128,128,128,255); /* gray line */
@@ -1204,7 +1320,7 @@ int main(int argc, char **argv)
/* debug: write digit info to stderr */
if(flags & DEBUG_OUTPUT) {
fprintf(stderr, "found %d digits\n", d);
fprintf(stderr, "found %d digits\n", number_of_digits);
for(d=0; d<number_of_digits; d++) {
fprintf(stderr, "digit %d: (%d,%d) -> (%d,%d), width: %d (%5.2f%%) "
"height: %d (%5.2f%%)\n",
ssocr.h
+4
View File
@@ -27,4 +27,8 @@ typedef struct {
int R, G, B, A;
} color_struct;
typedef struct {
int w, h;
} dimensions_struct;
#endif /* SSOCR2_H */