../operations/common/brightness-contrast.c
/* This file is an image processing operation for GEGL
*
* GEGL is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* GEGL 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with GEGL; if not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2006 Øyvind Kolås <pippin@gimp.org>
*/
#include "config.h"
#include <glib/gi18n-lib.h>
/* Followed by this #if ... */
#ifdef GEGL_CHANT_PROPERTIES
/* ... are the properties of the filter, these are all scalar values
* (doubles), the the parameters are:
* property name, min, max, default, "description of property"
*/
gegl_chant_double (contrast, _("Contrast"), -5.0, 5.0, 1.0,
_("Range scale factor"))
gegl_chant_double (brightness, _("Brightness"), -3.0, 3.0, 0.0,
_("Amount to increase brightness"))
/* this will create the instance structure for our use, and register the
* property with the given ranges, default values and a comment for the
* documentation/tooltip.
*/
#else
/* Specify the base class we're building our operation on, the base
* class provides a lot of the legwork so we do not have to. For
* brightness contrast the best base class is the POINT_FILTER base
* class.
*/
#define GEGL_CHANT_TYPE_POINT_FILTER
/* We specify the file we're in, this is needed to make the code
* generation for the properties work.
*/
#define GEGL_CHANT_C_FILE "brightness-contrast.c"
/* Including gegl-chant.h creates most of the GObject boiler plate
* needed, creating a GeglChant instance structure a GeglChantClass
* structure for our operation, as well as the needed code to register
* our new gobject with GEGL.
*/
#include "gegl-chant.h"
/* prepare() is called on each operation providing data to a node that
* is requested to provide a rendered result. When prepare is called
* all properties are known. For brightness contrast we use this
* opportunity to dictate the formats of the input and output buffers.
*/
static void prepare (GeglOperation *operation)
{
gegl_operation_set_format (operation, "input", babl_format ("RGBA float"));
gegl_operation_set_format (operation, "output", babl_format ("RGBA float"));
}
/* For GeglOperationPointFilter subclasses, we operate on linear
* buffers with a pixel count.
*/
static gboolean
process (GeglOperation *op,
void *in_buf,
void *out_buf,
glong n_pixels,
const GeglRectangle *roi)
{
/* Retrieve a pointer to GeglChantO structure which contains all the
* chanted properties
*/
GeglChantO *o = GEGL_CHANT_PROPERTIES (op);
gfloat *in_pixel;
gfloat *out_pixel;
gfloat brightness, contrast;
glong i;
in_pixel = in_buf;
out_pixel = out_buf;
brightness = o->brightness;
contrast = o->contrast;
for (i=0; i<n_pixels; i++)
{
gint component;
for (component=0; component <3 ; component++)
{
out_pixel[component] =
(in_pixel[component] - 0.5) * contrast + brightness + 0.5;
}
out_pixel[3] = in_pixel[3]; /* copy the alpha */
in_pixel += 4;
out_pixel += 4;
}
return TRUE;
}
static gboolean
process_rgb8 (GeglOperation *op,
void *in_buf,
void *out_buf,
glong n_pixels,
const GeglRectangle *roi)
{
/* Retrieve a pointer to GeglChantO structure which contains all the
* chanted properties
*/
GeglChantO *o = GEGL_CHANT_PROPERTIES (op);
gchar *in_pixel;
gchar *out_pixel;
gfloat brightness, contrast;
glong i;
in_pixel = in_buf;
out_pixel = out_buf;
brightness = o->brightness;
contrast = o->contrast;
for (i=0; i<n_pixels; i++)
{
gint component;
for (component=0; component <3 ; component++)
{
out_pixel[component] =
(in_pixel[component] - 128) * contrast + brightness * 255 + 128;
}
in_pixel += 3;
out_pixel += 3;
}
return TRUE;
}
static gboolean
process_rgba8 (GeglOperation *op,
void *in_buf,
void *out_buf,
glong n_pixels,
const GeglRectangle *roi)
{
/* Retrieve a pointer to GeglChantO structure which contains all the
* chanted properties
*/
GeglChantO *o = GEGL_CHANT_PROPERTIES (op);
gchar *in_pixel;
gchar *out_pixel;
gfloat brightness, contrast;
glong i;
in_pixel = in_buf;
out_pixel = out_buf;
brightness = o->brightness;
contrast = o->contrast;
for (i=0; i<n_pixels; i++)
{
gint component;
for (component=0; component <3 ; component++)
{
out_pixel[component] =
(in_pixel[component] - 128) * contrast + brightness * 255 + 128;
}
out_pixel[3] = in_pixel[3]; /* copy the alpha */
in_pixel += 4;
out_pixel += 4;
}
return TRUE;
}
#ifdef HAS_G4FLOAT
/* The compiler supports vector extensions allowing an version of
* the process code that produces more optimal instructions on the
* target platform.
*/
static gboolean
process_simd (GeglOperation *op,
void *in_buf,
void *out_buf,
glong samples,
const GeglRectangle *roi)
{
GeglChantO *o = GEGL_CHANT_PROPERTIES (op);
g4float *in = in_buf;
g4float *out = out_buf;
/* add 0.5 to brightness here to make the logic in the innerloop tighter
*/
g4float brightness = g4float_all(o->brightness + 0.5);
g4float contrast = g4float_all(o->contrast);
g4float half = g4float_half;
while (samples--)
{
*out = (*in - half) * contrast + brightness;
g4floatA(*out)=g4floatA(*in);
in ++;
out ++;
}
return TRUE;
}
#endif
static void gegl_operation_class_add_fast_path (
GeglOperationPointFilterClass *klass,
const Babl *format,
void *cb)
{
gint j=0;
while (klass->fp_format[j])
j++;
klass->fp_format[j] = format;
klass->fp_process[j] = (void*)cb;
}
/*
* The class init function sets up information needed for this operations class
* (template) in the GObject OO framework.
*/
static void
gegl_chant_class_init (GeglChantClass *klass)
{
GeglOperationClass *operation_class;
GeglOperationPointFilterClass *point_filter_class;
operation_class = GEGL_OPERATION_CLASS (klass);
point_filter_class = GEGL_OPERATION_POINT_FILTER_CLASS (klass);
/* override the prepare methods of the GeglOperation class */
operation_class->prepare = prepare;
/* override the process method of the point filter class (the process methods
* of our superclasses deal with the handling on their level of abstraction)
*/
point_filter_class->process = process;
gegl_operation_class_add_fast_path (point_filter_class,
babl_format ("R'G'B'A u8"),
process_rgba8);
gegl_operation_class_add_fast_path (point_filter_class,
babl_format ("R'G'B' u8"),
process_rgb8);
gegl_operation_class_add_fast_path (point_filter_class,
babl_format ("RGB u8"),
process_rgb8);
point_filter_class->fp_process [1] = process_rgb8;
point_filter_class->fp_format [1] = babl_format ("R'G'B' u8");
/* specify the name this operation is found under in the GUI/when
* programming/in XML
*/
operation_class->name = "gegl:brightness-contrast";
/* a colon separated list of categories/tags for this operations */
operation_class->categories = "color";
/* a description of what this operations does */
operation_class->description = _("Changes the light level and contrast.");
#ifdef HAS_G4FLOAT
/* add conditionally compiled variation of process(), gegl should be able
* to determine which is fastest and hopefully if any implementation is
* broken and not conforming to the reference implementation.
*/
gegl_operation_class_add_processor (operation_class,
G_CALLBACK (process_simd), "simd");
#endif
}
#endif /* closing #ifdef GEGL_CHANT_PROPERTIES ... else ... */
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