I've revised my code, adding comments and references. If there is anything to correct please write it.
Thank you, Robert Sasu
/* 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/>. * * Algorithm 1997 Eric L. Hernes (er...@rrnet.com) * Copyright 2011 Robert Sasu (sasu.rob...@gmail.com) */ #include "config.h" #include <glib/gi18n-lib.h> #ifdef GEGL_CHANT_PROPERTIES gegl_chant_double (azimuth, _("Azimuth"), 0.0, 360.0, 30.0, _("The value of azimuth")) gegl_chant_double (elevation, _("Elevation"), 0.0, 180.0, 45.0, _("The value of elevation")) gegl_chant_int (depth, _("Depth"), 1, 100, 20, _("Pixel depth")) gegl_chant_string (filter, _("Filter"), "emboss", _("Optional parameter to override automatic selection of emboss filert. " "Choices are emboss, blur-map" )) #else #define GEGL_CHANT_TYPE_AREA_FILTER #define GEGL_CHANT_C_FILE "emboss.c" #define RADIUS 3 #include "gegl-chant.h" #include <math.h> #include <stdio.h> /* * ANSI C code from the article * "Fast Embossing Effects on Raster Image Data" * by John Schlag, j...@kerner.com * in "Graphics Gems IV", Academic Press, 1994 * * * Emboss - shade 24-bit pixels using a single distant light source. * Normals are obtained by differentiating a monochrome 'bump' image. * The unary case ('texture' == NULL) uses the shading result as output. * The binary case multiples the optional 'texture' image by the shade. * Images are in row major order with interleaved color components (rgbrgb...). * E.g., component c of pixel x,y of 'dst' is dst[3*(y*width + x) + c]. * */ static void emboss (gfloat *src_buf, const GeglRectangle *src_rect, gfloat *dst_buf, const GeglRectangle *dst_rect, gint x, gchar *text, gint floats_per_pixel, gint alpha, gdouble azimuth, gdouble elevation, gint depth) { gint y; gint offset, verify; gint bytes; gdouble Lx = cos (azimuth) * cos (elevation); gdouble Ly = sin (azimuth) * cos (elevation); gdouble Lz = sin (elevation) ; gdouble Nz2 = 1 / (depth * depth); gdouble NzLz = (1 / depth) * Lz; bytes = (alpha) ? floats_per_pixel - 1 : floats_per_pixel; verify = src_rect->width*src_rect->height*floats_per_pixel; offset = x * dst_rect->width * floats_per_pixel; for (y = 0; y < dst_rect->width; y++) { gint i, j, b, count; gfloat Nx, Ny, NdotL; gfloat shade; gfloat M[3][3]; gfloat a; for (i = 0; i < 3; i++) for (j = 0; j < 3; j++) M[i][j] = 0.0; for (b = 0; b < bytes; b++) { for (i = 0; i < 3; i++) for (j = 0; j < 3; j++) { count = ((x+i-1)*src_rect->width + (y+j-1))*floats_per_pixel + bytes; /*verify each time that we are in the source image*/ if (alpha && count >= 0 && count < verify) a = src_buf[count]; else a = 1.0; /*calculate recalculate the sorrounding pixels by multiplication*/ /*after we have that we can calculate new value of the pixel*/ if ((count - bytes + b) >= 0 && (count - bytes + b) < verify) M[i][j] += a * src_buf[count - bytes + b]; } } Nx = M[0][0] + M[1][0] + M[2][0] - M[0][2] - M[1][2] - M[2][2]; Ny = M[2][0] + M[2][1] + M[2][2] - M[0][0] - M[0][1] - M[0][2]; /*calculating the shading result (same as in gimp)*/ if ( Nx == 0 && Ny == 0 ) shade = Lz; else if ( (NdotL = Nx * Lx + Ny * Ly + NzLz) < 0 ) shade = 0; else shade = NdotL / sqrt(Nx*Nx + Ny*Ny + Nz2); count = (x*src_rect->width + y)*floats_per_pixel; /*setting the value of the destination buffer*/ if (bytes == 1) dst_buf[offset++] = shade; else { /*recalculating every byte of a pixel*/ /*by multiplying with the shading result*/ for (b = 0; b < bytes; b++) if ((count + b) >= 0 && (count + b) < verify) dst_buf[offset++] = (src_buf[count+b] * shade) ; else dst_buf[offset++] = 1.0; /*preserving alpha*/ if (alpha && (count + bytes) >= 0 && (count + bytes) < verify) dst_buf[offset++] = src_buf[count + bytes]; else dst_buf[offset++] = 1.0 ; } } } static void prepare (GeglOperation *operation) { GeglChantO *o = GEGL_CHANT_PROPERTIES (operation); GeglOperationAreaFilter *op_area = GEGL_OPERATION_AREA_FILTER (operation); gchar *type; gboolean filter_blurmap; op_area->left=op_area->right=op_area->top=op_area->bottom=3; filter_blurmap = o->filter && !strcmp(o->filter, "blur-map"); type = (filter_blurmap) ? "RGBA float" : "Y float"; gegl_operation_set_format (operation, "output", babl_format (type)); } static gboolean process (GeglOperation *operation, GeglBuffer *input, GeglBuffer *output, const GeglRectangle *result) { GeglChantO *o = GEGL_CHANT_PROPERTIES (operation); GeglOperationAreaFilter *op_area = GEGL_OPERATION_AREA_FILTER (operation); GeglRectangle rect; gfloat *src_buf; gfloat *dst_buf; gboolean filter_blurmap; gchar *type; gint x; gint floats_per_pixel; /*blur-map or emboss*/ filter_blurmap = o->filter && !strcmp(o->filter, "blur-map"); type = (filter_blurmap) ? "RGBA float" : "Y float"; floats_per_pixel = (filter_blurmap) ? 4 : 1; rect.x = result->x - op_area->left; rect.width = result->width + op_area->left + op_area->right; rect.y = result->y - op_area->top; rect.height = result->height + op_area->top + op_area->bottom; src_buf = g_new0 (gfloat, rect.width * rect.height * floats_per_pixel); dst_buf = g_new0 (gfloat, rect.width * rect.height * floats_per_pixel); gegl_buffer_get (input, 1.0, &rect, babl_format (type), src_buf, GEGL_AUTO_ROWSTRIDE); /*do for every row*/ for (x = 0; x < rect.height; x++) emboss(src_buf, &rect, dst_buf, &rect, x, type, floats_per_pixel, (filter_blurmap) ? 1 : 0, o->azimuth, o->elevation, o->depth); gegl_buffer_set (output, &rect, babl_format (type), dst_buf, GEGL_AUTO_ROWSTRIDE); g_free (src_buf); g_free (dst_buf); return TRUE; } static void gegl_chant_class_init (GeglChantClass *klass) { GeglOperationClass *operation_class; GeglOperationFilterClass *filter_class; operation_class = GEGL_OPERATION_CLASS (klass); filter_class = GEGL_OPERATION_FILTER_CLASS (klass); filter_class->process = process; operation_class->prepare = prepare; operation_class->categories = "distort"; operation_class->name = "gegl:emboss"; operation_class->description = _("Performs embossing on the image."); } #endif
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