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Ghostscript (gstoraster): add halftone gamma value #161

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Merged
tillkamppeter merged 2 commits into from
Jun 23, 2026
Merged

Ghostscript (gstoraster): add halftone gamma value #161

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b5bfdb4
Ghostscript filters (gsto...): remove default gamma from spot halftone
ValdikSS Jun 23, 2026
dc13bb1
Ghostscript filters (gsto...): add halftone gamma value
ValdikSS Jun 23, 2026
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45 changes: 33 additions & 12 deletions cupsfilters/ghostscript.c
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Original file line number Diff line number Diff line change
Expand Up @@ -867,7 +867,7 @@ cfFilterGhostscript(int inputfd, // I - File descriptor input
cf_cm_calibration_t cm_calibrate;
int pxlcolor = 0; // 1 if printer is color printer otherwise 0.
cups_halftone_type_t halftonetype = HALFTONE_DEFAULT;
int ht_frequency = 133, ht_angle = 45, ht_dotshape = 0;
int ht_frequency = 133, ht_angle = 45, ht_dotshape = 0, ht_gamma = 0;
ipp_attribute_t *ipp_attr;
cf_logfunc_t log = data->logfunc;
void *ld = data->logdata;
Expand Down Expand Up @@ -1701,7 +1701,13 @@ cfFilterGhostscript(int inputfd, // I - File descriptor input
{
p++;
v = strtol(p, &endp, 10);
if (endp != p) ht_dotshape = (int)v;
if (endp != p) { ht_dotshape = (int)v; p = endp; }
if (*p == '-')
{
p++;
v = strtol(p, &endp, 10);
if (endp != p) ht_gamma = (int)v;
}
}
}
}
Expand All @@ -1726,7 +1732,13 @@ cfFilterGhostscript(int inputfd, // I - File descriptor input
{
p++;
v = strtol(p, &endp, 10);
if (endp != p) ht_dotshape = (int)v;
if (endp != p) { ht_dotshape = (int)v; p = endp; }
if (*p == '-')
{
p++;
v = strtol(p, &endp, 10);
if (endp != p) ht_gamma = (int)v;
}
}
}
}
Expand Down Expand Up @@ -1896,13 +1908,18 @@ cfFilterGhostscript(int inputfd, // I - File descriptor input
// 0=CIRCLE, 1=REDBOOK, 2=INVERTED, 3=RHOMBOID, 4=LINE_X, 5=LINE_Y,
// 6=DIAMOND1, 7=DIAMOND2, 8=ROUNDSPOT */
//
if (halftonetype == HALFTONE_GENORDERED) {
if (halftonetype == HALFTONE_GENORDERED)
{
char ht_transfer[16] = {0};
if (ht_gamma >= 1 && ht_gamma <= 99)
snprintf(ht_transfer, sizeof(ht_transfer), "0.%02d exp", ht_gamma);
if (log) log(ld, CF_LOGLEVEL_DEBUG,
"cfFilterGhostscript: Ghostscript using .genordered halftone (frequency=%d angle=%d dotshape=%d).",
ht_frequency, ht_angle, ht_dotshape);
"cfFilterGhostscript: Ghostscript using .genordered halftone (frequency=%d angle=%d dotshape=%d gamma=%s).",
ht_frequency, ht_angle, ht_dotshape,
ht_transfer[0] ? ht_transfer : "default");
snprintf(tmpstr, sizeof(tmpstr),
"<< /Frequency %d /Angle %d /DotShape %d >> .genordered /Default exch /Halftone defineresource sethalftone { } settransfer 0.003 setsmoothness",
ht_frequency, ht_angle, ht_dotshape);
"<< /Frequency %d /Angle %d /DotShape %d >> .genordered /Default exch /Halftone defineresource sethalftone { %s } settransfer 0.003 setsmoothness",
ht_frequency, ht_angle, ht_dotshape, ht_transfer);
cupsArrayAdd(gs_args, strdup(tmpstr));
}

Expand All @@ -1914,14 +1931,18 @@ cfFilterGhostscript(int inputfd, // I - File descriptor input
if (halftonetype == HALFTONE_SPOT)
{
int shape = ht_dotshape;
char ht_transfer[16] = {0};
if (shape < 0) shape = 0;
if (shape >= HT_SPOT_FUNCTIONS_COUNT) shape = HT_SPOT_FUNCTIONS_COUNT - 1;
if (ht_gamma >= 1 && ht_gamma <= 99)
snprintf(ht_transfer, sizeof(ht_transfer), "0.%02d exp", ht_gamma);
if (log) log(ld, CF_LOGLEVEL_DEBUG,
"cfFilterGhostscript: Ghostscript using Spot halftone (frequency=%d angle=%d dotshape=%d).\n",
ht_frequency, ht_angle, shape);
"cfFilterGhostscript: Ghostscript using Spot halftone (frequency=%d angle=%d dotshape=%d gamma=%s).\n",
ht_frequency, ht_angle, shape,
ht_transfer[0] ? ht_transfer : "default");
snprintf(tmpstr, sizeof(tmpstr),
"<< /HalftoneType 1 /Frequency %d /Angle %d /SpotFunction %s >> /Default exch /Halftone defineresource sethalftone",
ht_frequency, ht_angle, ht_spot_functions[shape]);
"<< /HalftoneType 1 /Frequency %d /Angle %d /SpotFunction %s >> /Default exch /Halftone defineresource sethalftone { %s } settransfer 0.003 setsmoothness",
ht_frequency, ht_angle, ht_spot_functions[shape], ht_transfer);
cupsArrayAdd(gs_args, strdup(tmpstr));
}

Expand Down
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