dlib.image.filters.normalmap source code

1 /*
2 Copyright (c) 2011-2021 Timur Gafarov
3 
4 Boost Software License - Version 1.0 - August 17th, 2003
5 
6 Permission is hereby granted, free of charge, to any person or organization
7 obtaining a copy of the software and accompanying documentation covered by
8 this license (the "Software") to use, reproduce, display, distribute,
9 execute, and transmit the Software, and to prepare derivative works of the
10 Software, and to permit third-parties to whom the Software is furnished to
11 do so, all subject to the following:
12 
13 The copyright notices in the Software and this entire statement, including
14 the above license grant, this restriction and the following disclaimer,
15 must be included in all copies of the Software, in whole or in part, and
16 all derivative works of the Software, unless such copies or derivative
17 works are solely in the form of machine-executable object code generated by
18 a source language processor.
19 
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26 DEALINGS IN THE SOFTWARE.
27 */
28 
29 /**
30  * Normal map generation
31  *
32  * Copyright: Timur Gafarov 2011-2021.
33  * License: $(LINK2 boost.org/LICENSE_1_0.txt, Boost License 1.0).
34  * Authors: Timur Gafarov
35  */
36 module dlib.image.filters.normalmap;
37 
38 import dlib.image.image;
39 import dlib.image.color;
40 import dlib.math.vector;
41 
42 /// Generate normal map from height map using Sobel operator
43 SuperImage heightToNormal(
44     SuperImage img,
45     SuperImage outp,
46     Channel channel = Channel.R,
47     float strength = 2.0f)
48 in
49 {
50     assert (img.data.length);
51 }
52 do
53 {
54     // TODO: optionally transfer height data to alpha channel
55     SuperImage res;
56     if (outp)
57         res = outp;
58     else
59         res = img.dup;
60 
61     if (img.channels == 1)
62         channel = Channel.R;
63 
64     float[8] sobelTaps;
65 
66     foreach(y; 0..img.height)
67     foreach(x; 0..img.width)
68     {
69         sobelTaps[0] = img[x-1, y-1][channel];
70         sobelTaps[1] = img[x,   y-1][channel];
71         sobelTaps[2] = img[x+1, y-1][channel];
72         sobelTaps[3] = img[x-1, y+1][channel];
73         sobelTaps[4] = img[x,   y+1][channel];
74         sobelTaps[5] = img[x+1, y+1][channel];
75         sobelTaps[6] = img[x-1, y  ][channel];
76         sobelTaps[7] = img[x+1, y  ][channel];
77 
78         float dx, dy;
79 
80         // Do y sobel filter
81         dy  = sobelTaps[0] * +1.0f;
82         dy += sobelTaps[1] * +2.0f;
83         dy += sobelTaps[2] * +1.0f;
84         dy += sobelTaps[3] * -1.0f;
85         dy += sobelTaps[4] * -2.0f;
86         dy += sobelTaps[5] * -1.0f;
87 
88         // Do x sobel filter
89         dx  = sobelTaps[0] * -1.0f;
90         dx += sobelTaps[6] * -2.0f;
91         dx += sobelTaps[3] * -1.0f;
92         dx += sobelTaps[2] * +1.0f;
93         dx += sobelTaps[7] * +2.0f;
94         dx += sobelTaps[5] * +1.0f;
95 
96         // pack normal into floating-point RGBA
97         Vector3f normal = Vector3f(-dx, -dy, 1.0f / strength);
98         Color4f col = packNormal(normal);
99         col.a = 1.0f;
100 
101         // write result
102         res[x, y] = col;
103     }
104 
105     return res;
106 }
107 
108 /// ditto
109 SuperImage heightToNormal(
110     SuperImage img,
111     Channel channel = Channel.R,
112     float strength = 2.0f)
113 {
114     return heightToNormal(img, null, channel, strength);
115 }