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gimp/plug-ins/common/hot.c

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/*
* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* hot.c - Scan an image for pixels with RGB values that will give
* "unsafe" values of chrominance signal or composite signal
* amplitude when encoded into an NTSC or PAL color signal.
* (This happens for certain high-intensity high-saturation colors
* that are rare in real scenes, but can easily be present
* in synthetic images.)
*
* Such pixels can be flagged so the user may then choose other
* colors. Or, the offending pixels can be made "safe"
* in a manner that preserves hue.
*
* There are two reasonable ways to make a pixel "safe":
* We can reduce its intensity (luminance) while leaving
* hue and saturation the same. Or, we can reduce saturation
* while leaving hue and luminance the same. A #define selects
* which strategy to use.
*
* Note to the user: You must add your own read_pixel() and write_pixel()
* routines. You may have to modify pix_decode() and pix_encode().
* MAXPIX, WID, and HGT are likely to need modification.
*/
/*
* Originally written as "ikNTSC.c" by Alan Wm Paeth,
* University of Waterloo, August, 1985
* Updated by Dave Martindale, Imax Systems Corp., December 1990
*/
/*
* Compile time options:
*
*
* CHROMA_LIM is the limit (in IRE units) of the overall
* chrominance amplitude; it should be 50 or perhaps
* very slightly higher.
*
* COMPOS_LIM is the maximum amplitude (in IRE units) allowed for
* the composite signal. A value of 100 is the maximum
* monochrome white, and is always safe. 120 is the absolute
* limit for NTSC broadcasting, since the transmitter's carrier
* goes to zero with 120 IRE input signal. Generally, 110
* is a good compromise - it allows somewhat brighter colors
* than 100, while staying safely away from the hard limit.
*/
#include "config.h"
#include <string.h>
#include <libgimp/gimp.h>
#include <libgimp/gimpui.h>
#include "libgimp/stdplugins-intl.h"
#define PLUG_IN_PROC "plug-in-hot"
#define PLUG_IN_BINARY "hot"
#define PLUG_IN_ROLE "gimp-hot"
typedef struct
{
gint32 image;
gint32 drawable;
gint32 mode;
gint32 action;
gint32 new_layerp;
} piArgs;
typedef enum
{
ACT_LREDUX,
ACT_SREDUX,
ACT_FLAG
} hotAction;
typedef enum
{
MODE_NTSC,
MODE_PAL
} hotModes;
#define CHROMA_LIM 50.0 /* chroma amplitude limit */
#define COMPOS_LIM 110.0 /* max IRE amplitude */
/*
* RGB to YIQ encoding matrix.
*/
struct
{
gdouble pedestal;
gdouble gamma;
gdouble code[3][3];
} static mode[2] = {
{
7.5,
2.2,
{
{ 0.2989, 0.5866, 0.1144 },
{ 0.5959, -0.2741, -0.3218 },
{ 0.2113, -0.5227, 0.3113 }
}
},
{
0.0,
2.8,
{
{ 0.2989, 0.5866, 0.1144 },
{ -0.1473, -0.2891, 0.4364 },
{ 0.6149, -0.5145, -0.1004 }
}
}
};
#define SCALE 8192 /* scale factor: do floats with int math */
#define MAXPIX 255 /* white value */
static gint tab[3][3][MAXPIX+1]; /* multiply lookup table */
static gdouble chroma_lim; /* chroma limit */
static gdouble compos_lim; /* composite amplitude limit */
static glong ichroma_lim2; /* chroma limit squared (scaled integer) */
static gint icompos_lim; /* composite amplitude limit (scaled integer) */
static void query (void);
static void run (const gchar *name,
gint nparam,
const GimpParam *param,
gint *nretvals,
GimpParam **retvals);
static gboolean pluginCore (piArgs *argp);
static gboolean plugin_dialog (piArgs *argp);
static gboolean hotp (guint8 r,
guint8 g,
guint8 b);
static void build_tab (gint m);
/*
* gc: apply the gamma correction specified for this video standard.
* inv_gc: inverse function of gc.
*
* These are generally just a call to pow(), but be careful!
* Future standards may use more complex functions.
* (e.g. SMPTE 240M's "electro-optic transfer characteristic").
*/
#define gc(x,m) pow(x, 1.0 / mode[m].gamma)
#define inv_gc(x,m) pow(x, mode[m].gamma)
/*
* pix_decode: decode an integer pixel value into a floating-point
* intensity in the range [0, 1].
*
* pix_encode: encode a floating-point intensity into an integer
* pixel value.
*
* The code given here assumes simple linear encoding; you must change
* these routines if you use a different pixel encoding technique.
*/
#define pix_decode(v) ((double)v / (double)MAXPIX)
#define pix_encode(v) ((int)(v * (double)MAXPIX + 0.5))
const GimpPlugInInfo PLUG_IN_INFO =
{
NULL, /* init_proc */
NULL, /* quit_proc */
query, /* query_proc */
run, /* run_proc */
};
MAIN ()
static void
query (void)
{
static const GimpParamDef args[] =
{
{ GIMP_PDB_INT32, "run-mode", "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }" },
{ GIMP_PDB_IMAGE, "image", "The Image" },
{ GIMP_PDB_DRAWABLE, "drawable", "The Drawable" },
{ GIMP_PDB_INT32, "mode", "Mode { NTSC (0), PAL (1) }" },
{ GIMP_PDB_INT32, "action", "The action to perform" },
{ GIMP_PDB_INT32, "new-layer", "Create a new layer { TRUE, FALSE }" }
};
gimp_install_procedure (PLUG_IN_PROC,
N_("Find and fix pixels that may be unsafely bright"),
"hot scans an image for pixels that will give unsave "
"values of chrominance or composite signale "
"amplitude when encoded into an NTSC or PAL signal. "
"Three actions can be performed on these ``hot'' "
"pixels. (0) reduce luminance, (1) reduce "
"saturation, or (2) Blacken.",
"Eric L. Hernes, Alan Wm Paeth",
"Eric L. Hernes",
"1997",
N_("_Hot..."),
"RGB",
GIMP_PLUGIN,
G_N_ELEMENTS (args), 0,
args, NULL);
gimp_plugin_menu_register (PLUG_IN_PROC, "<Image>/Colors/Modify");
}
static void
run (const gchar *name,
gint nparam,
const GimpParam *param,
gint *nretvals,
GimpParam **retvals)
{
static GimpParam rvals[1];
piArgs args;
*nretvals = 1;
*retvals = rvals;
INIT_I18N ();
memset (&args, 0, sizeof (args));
args.mode = -1;
gimp_get_data (PLUG_IN_PROC, &args);
args.image = param[1].data.d_image;
args.drawable = param[2].data.d_drawable;
rvals[0].type = GIMP_PDB_STATUS;
rvals[0].data.d_status = GIMP_PDB_SUCCESS;
switch (param[0].data.d_int32)
{
case GIMP_RUN_INTERACTIVE:
/* XXX: add code here for interactive running */
if (args.mode == -1)
{
args.mode = MODE_NTSC;
args.action = ACT_LREDUX;
args.new_layerp = 1;
}
if (plugin_dialog (&args))
{
if (! pluginCore (&args))
{
rvals[0].data.d_status = GIMP_PDB_EXECUTION_ERROR;
}
}
else
{
rvals[0].data.d_status = GIMP_PDB_CANCEL;
}
gimp_set_data (PLUG_IN_PROC, &args, sizeof (args));
break;
case GIMP_RUN_NONINTERACTIVE:
/* XXX: add code here for non-interactive running */
if (nparam != 6)
{
rvals[0].data.d_status = GIMP_PDB_CALLING_ERROR;
break;
}
args.mode = param[3].data.d_int32;
args.action = param[4].data.d_int32;
args.new_layerp = param[5].data.d_int32;
if (! pluginCore (&args))
{
rvals[0].data.d_status = GIMP_PDB_EXECUTION_ERROR;
break;
}
break;
case GIMP_RUN_WITH_LAST_VALS:
/* XXX: add code here for last-values running */
if (! pluginCore (&args))
{
rvals[0].data.d_status = GIMP_PDB_EXECUTION_ERROR;
}
break;
}
}
static gboolean
pluginCore (piArgs *argp)
{
GimpDrawable *drw, *ndrw = NULL;
GimpPixelRgn srcPr, dstPr;
gboolean success = TRUE;
gint nl = 0;
gint y, i;
gint Y, I, Q;
gint width, height, bpp;
gint sel_x1, sel_x2, sel_y1, sel_y2;
gint prog_interval;
guchar *src, *s, *dst, *d;
guchar r, prev_r=0, new_r=0;
guchar g, prev_g=0, new_g=0;
guchar b, prev_b=0, new_b=0;
gdouble fy, fc, t, scale;
gdouble pr, pg, pb;
gdouble py;
drw = gimp_drawable_get (argp->drawable);
width = drw->width;
height = drw->height;
bpp = drw->bpp;
if (argp->new_layerp)
{
gchar name[40];
const gchar *mode_names[] =
{
"ntsc",
"pal",
};
const gchar *action_names[] =
{
"lum redux",
"sat redux",
"flag",
};
g_snprintf (name, sizeof (name), "hot mask (%s, %s)",
mode_names[argp->mode],
action_names[argp->action]);
nl = gimp_layer_new (argp->image, name, width, height,
GIMP_RGBA_IMAGE,
100,
gimp_image_get_default_new_layer_mode (argp->image));
ndrw = gimp_drawable_get (nl);
gimp_drawable_fill (nl, GIMP_FILL_TRANSPARENT);
gimp_image_insert_layer (argp->image, nl, -1, 0);
}
if (! gimp_drawable_mask_intersect (drw->drawable_id,
&sel_x1, &sel_y1, &width, &height))
return success;
sel_x2 = sel_x1 + width;
sel_y2 = sel_y1 + height;
src = g_new (guchar, width * height * bpp);
dst = g_new (guchar, width * height * 4);
gimp_pixel_rgn_init (&srcPr, drw, sel_x1, sel_y1, width, height,
FALSE, FALSE);
if (argp->new_layerp)
{
gimp_pixel_rgn_init (&dstPr, ndrw, sel_x1, sel_y1, width, height,
FALSE, FALSE);
}
else
{
gimp_pixel_rgn_init (&dstPr, drw, sel_x1, sel_y1, width, height,
TRUE, TRUE);
}
gimp_pixel_rgn_get_rect (&srcPr, src, sel_x1, sel_y1, width, height);
s = src;
d = dst;
build_tab (argp->mode);
gimp_progress_init (_("Hot"));
prog_interval = height / 10;
for (y = sel_y1; y < sel_y2; y++)
{
gint x;
if (y % prog_interval == 0)
gimp_progress_update ((double) y / (double) (sel_y2 - sel_y1));
for (x = sel_x1; x < sel_x2; x++)
{
if (hotp (r = *(s + 0), g = *(s + 1), b = *(s + 2)))
{
if (argp->action == ACT_FLAG)
{
for (i = 0; i < 3; i++)
*d++ = 0;
s += 3;
if (bpp == 4)
*d++ = *s++;
else if (argp->new_layerp)
*d++ = 255;
}
else
{
/*
* Optimization: cache the last-computed hot pixel.
*/
if (r == prev_r && g == prev_g && b == prev_b)
{
*d++ = new_r;
*d++ = new_g;
*d++ = new_b;
s += 3;
if (bpp == 4)
*d++ = *s++;
else if (argp->new_layerp)
*d++ = 255;
}
else
{
Y = tab[0][0][r] + tab[0][1][g] + tab[0][2][b];
I = tab[1][0][r] + tab[1][1][g] + tab[1][2][b];
Q = tab[2][0][r] + tab[2][1][g] + tab[2][2][b];
prev_r = r;
prev_g = g;
prev_b = b;
/*
* Get Y and chroma amplitudes in floating point.
*
* If your C library doesn't have hypot(), just use
* hypot(a,b) = sqrt(a*a, b*b);
*
* Then extract linear (un-gamma-corrected)
* floating-point pixel RGB values.
*/
fy = (double)Y / (double)SCALE;
fc = hypot ((double) I / (double) SCALE,
(double) Q / (double) SCALE);
pr = (double) pix_decode (r);
pg = (double) pix_decode (g);
pb = (double) pix_decode (b);
/*
* Reducing overall pixel intensity by scaling R,
* G, and B reduces Y, I, and Q by the same factor.
* This changes luminance but not saturation, since
* saturation is determined by the chroma/luminance
* ratio.
*
* On the other hand, by linearly interpolating
* between the original pixel value and a grey
* pixel with the same luminance (R=G=B=Y), we
* change saturation without affecting luminance.
*/
if (argp->action == ACT_LREDUX)
{
/*
* Calculate a scale factor that will bring the pixel
* within both chroma and composite limits, if we scale
* luminance and chroma simultaneously.
*
* The calculated chrominance reduction applies
* to the gamma-corrected RGB values that are
* the input to the RGB-to-YIQ operation.
* Multiplying the original un-gamma-corrected
* pixel values by the scaling factor raised to
* the "gamma" power is equivalent, and avoids
* calling gc() and inv_gc() three times each. */
scale = chroma_lim / fc;
t = compos_lim / (fy + fc);
if (t < scale)
scale = t;
scale = pow (scale, mode[argp->mode].gamma);
r = (guint8) pix_encode (scale * pr);
g = (guint8) pix_encode (scale * pg);
b = (guint8) pix_encode (scale * pb);
}
else
{ /* ACT_SREDUX hopefully */
/*
* Calculate a scale factor that will bring the
* pixel within both chroma and composite
* limits, if we scale chroma while leaving
* luminance unchanged.
*
* We have to interpolate gamma-corrected RGB
* values, so we must convert from linear to
* gamma-corrected before interpolation and then
* back to linear afterwards.
*/
scale = chroma_lim / fc;
t = (compos_lim - fy) / fc;
if (t < scale)
scale = t;
pr = gc (pr, argp->mode);
pg = gc (pg, argp->mode);
pb = gc (pb, argp->mode);
py = pr * mode[argp->mode].code[0][0] +
pg * mode[argp->mode].code[0][1] +
pb * mode[argp->mode].code[0][2];
r = pix_encode (inv_gc (py + scale * (pr - py),
argp->mode));
g = pix_encode (inv_gc (py + scale * (pg - py),
argp->mode));
b = pix_encode (inv_gc (py + scale * (pb - py),
argp->mode));
}
*d++ = new_r = r;
*d++ = new_g = g;
*d++ = new_b = b;
s += 3;
if (bpp == 4)
*d++ = *s++;
else if (argp->new_layerp)
*d++ = 255;
}
}
}
else
{
if (!argp->new_layerp)
{
for (i = 0; i < bpp; i++)
*d++ = *s++;
}
else
{
s += bpp;
d += 4;
}
}
}
}
gimp_progress_update (1.0);
gimp_pixel_rgn_set_rect (&dstPr, dst, sel_x1, sel_y1, width, height);
g_free (src);
g_free (dst);
if (argp->new_layerp)
{
gimp_drawable_flush (ndrw);
gimp_drawable_update (nl, sel_x1, sel_y1, width, height);
}
else
{
gimp_drawable_flush (drw);
gimp_drawable_merge_shadow (drw->drawable_id, TRUE);
gimp_drawable_update (drw->drawable_id, sel_x1, sel_y1, width, height);
}
gimp_displays_flush ();
return success;
}
static gboolean
plugin_dialog (piArgs *argp)
{
GtkWidget *dlg;
GtkWidget *hbox;
GtkWidget *vbox;
GtkWidget *toggle;
GtkWidget *frame;
gboolean run;
gimp_ui_init (PLUG_IN_BINARY, FALSE);
dlg = gimp_dialog_new (_("Hot"), PLUG_IN_ROLE,
NULL, 0,
gimp_standard_help_func, PLUG_IN_PROC,
_("_Cancel"), GTK_RESPONSE_CANCEL,
_("_OK"), GTK_RESPONSE_OK,
NULL);
gtk_dialog_set_alternative_button_order (GTK_DIALOG (dlg),
GTK_RESPONSE_OK,
GTK_RESPONSE_CANCEL,
-1);
gimp_window_set_transient (GTK_WINDOW (dlg));
hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 12);
gtk_container_set_border_width (GTK_CONTAINER (hbox), 12);
gtk_box_pack_start (GTK_BOX (gtk_dialog_get_content_area (GTK_DIALOG (dlg))),
hbox, TRUE, TRUE, 0);
gtk_widget_show (hbox);
vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
gtk_box_pack_start (GTK_BOX (hbox), vbox, TRUE, TRUE, 0);
gtk_widget_show (vbox);
frame = gimp_int_radio_group_new (TRUE, _("Mode"),
G_CALLBACK (gimp_radio_button_update),
&argp->mode, argp->mode,
"N_TSC", MODE_NTSC, NULL,
"_PAL", MODE_PAL, NULL,
NULL);
gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
gtk_widget_show (frame);
toggle = gtk_check_button_new_with_mnemonic (_("Create _new layer"));
gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle), argp->new_layerp);
gtk_box_pack_start (GTK_BOX (vbox), toggle, FALSE, FALSE, 0);
gtk_widget_show (toggle);
g_signal_connect (toggle, "toggled",
G_CALLBACK (gimp_toggle_button_update),
&argp->new_layerp);
frame = gimp_int_radio_group_new (TRUE, _("Action"),
G_CALLBACK (gimp_radio_button_update),
&argp->action, argp->action,
_("Reduce _Luminance"), ACT_LREDUX, NULL,
_("Reduce _Saturation"), ACT_SREDUX, NULL,
_("_Blacken"), ACT_FLAG, NULL,
NULL);
gtk_box_pack_start (GTK_BOX (hbox), frame, FALSE, FALSE, 0);
gtk_widget_show (frame);
gtk_widget_show (dlg);
run = (gimp_dialog_run (GIMP_DIALOG (dlg)) == GTK_RESPONSE_OK);
gtk_widget_destroy (dlg);
return run;
}
/*
* build_tab: Build multiply lookup table.
*
* For each possible pixel value, decode value into floating-point
* intensity. Then do gamma correction required by the video
* standard. Scale the result by our fixed-point scale factor.
* Then calculate 9 lookup table entries for this pixel value.
*
* We also calculate floating-point and scaled integer versions
* of our limits here. This prevents evaluating expressions every pixel
* when the compiler is too stupid to evaluate constant-valued
* floating-point expressions at compile time.
*
* For convenience, the limits are #defined using IRE units.
* We must convert them here into the units in which YIQ
* are measured. The conversion from IRE to internal units
* depends on the pedestal level in use, since as Y goes from
* 0 to 1, the signal goes from the pedestal level to 100 IRE.
* Chroma is always scaled to remain consistent with Y.
*/
static void
build_tab (int m)
{
double f;
int pv;
for (pv = 0; pv <= MAXPIX; pv++)
{
f = (double)SCALE * (double)gc((double)pix_decode(pv),m);
tab[0][0][pv] = (int)(f * mode[m].code[0][0] + 0.5);
tab[0][1][pv] = (int)(f * mode[m].code[0][1] + 0.5);
tab[0][2][pv] = (int)(f * mode[m].code[0][2] + 0.5);
tab[1][0][pv] = (int)(f * mode[m].code[1][0] + 0.5);
tab[1][1][pv] = (int)(f * mode[m].code[1][1] + 0.5);
tab[1][2][pv] = (int)(f * mode[m].code[1][2] + 0.5);
tab[2][0][pv] = (int)(f * mode[m].code[2][0] + 0.5);
tab[2][1][pv] = (int)(f * mode[m].code[2][1] + 0.5);
tab[2][2][pv] = (int)(f * mode[m].code[2][2] + 0.5);
}
chroma_lim = (double)CHROMA_LIM / (100.0 - mode[m].pedestal);
compos_lim = ((double)COMPOS_LIM - mode[m].pedestal) /
(100.0 - mode[m].pedestal);
ichroma_lim2 = (int)(chroma_lim * SCALE + 0.5);
ichroma_lim2 *= ichroma_lim2;
icompos_lim = (int)(compos_lim * SCALE + 0.5);
}
static gboolean
hotp (guint8 r,
guint8 g,
guint8 b)
{
int y, i, q;
long y2, c2;
/*
* Pixel decoding, gamma correction, and matrix multiplication
* all done by lookup table.
*
* "i" and "q" are the two chrominance components;
* they are I and Q for NTSC.
* For PAL, "i" is U (scaled B-Y) and "q" is V (scaled R-Y).
* Since we only care about the length of the chroma vector,
* not its angle, we don't care which is which.
*/
y = tab[0][0][r] + tab[0][1][g] + tab[0][2][b];
i = tab[1][0][r] + tab[1][1][g] + tab[1][2][b];
q = tab[2][0][r] + tab[2][1][g] + tab[2][2][b];
/*
* Check to see if the chrominance vector is too long or the
* composite waveform amplitude is too large.
*
* Chrominance is too large if
*
* sqrt(i^2, q^2) > chroma_lim.
*
* The composite signal amplitude is too large if
*
* y + sqrt(i^2, q^2) > compos_lim.
*
* We avoid doing the sqrt by checking
*
* i^2 + q^2 > chroma_lim^2
* and
* y + sqrt(i^2 + q^2) > compos_lim
* sqrt(i^2 + q^2) > compos_lim - y
* i^2 + q^2 > (compos_lim - y)^2
*
*/
c2 = (long)i * i + (long)q * q;
y2 = (long)icompos_lim - y;
y2 *= y2;
if (c2 <= ichroma_lim2 && c2 <= y2)
{ /* no problems */
return FALSE;
}
return TRUE;
}
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