1// -*- C++;indent-tabs-mode: t; tab-width: 4; c-basic-offset: 4; -*-
2
3/**
4* KImageIO Routines to read (and perhaps in the future, write) images
5* in the high dynamic range EXR format.
6* Copyright (c) 2003, Brad Hards <bradh@frogmouth.net>
7*
8* This library is distributed under the conditions of the GNU LGPL.
9*/
10
11#include "exr.h"
12
13#include <config.h>
14
15#include <ImfRgbaFile.h>
16#include <ImfStandardAttributes.h>
17#include <ImathBox.h>
18#include <ImfInputFile.h>
19#include <ImfBoxAttribute.h>
20#include <ImfChannelListAttribute.h>
21#include <ImfCompressionAttribute.h>
22#include <ImfFloatAttribute.h>
23#include <ImfIntAttribute.h>
24#include <ImfLineOrderAttribute.h>
25#include <ImfStringAttribute.h>
26#include <ImfVecAttribute.h>
27#include <ImfArray.h>
28#include <ImfConvert.h>
29#include <ImfVersion.h>
30#include <IexThrowErrnoExc.h>
31
32#include <iostream>
33
34#include <kdebug.h>
35
36
37#include <QImage>
38#include <QDataStream>
39#include <QImageIOPlugin>
40
41class K_IStream: public Imf::IStream
42{
43public:
44 K_IStream( QIODevice *dev, const QByteArray& fileName ):
45 IStream( fileName.data() ), m_dev ( dev )
46 {}
47
48 virtual bool read( char c[], int n );
49 virtual Imf::Int64 tellg( );
50 virtual void seekg( Imf::Int64 pos );
51 virtual void clear( );
52
53private:
54 QIODevice *m_dev;
55};
56
57bool K_IStream::read( char c[], int n )
58{
59 qint64 result = m_dev->read( c, n );
60 if ( result > 0 ) {
61 return true;
62 } else if ( result == 0 ) {
63 throw Iex::InputExc( "Unexpected end of file" );
64 } else // negative value {
65 Iex::throwErrnoExc( "Error in read", result );
66 return false;
67}
68
69Imf::Int64 K_IStream::tellg( )
70{
71 return m_dev->pos();
72}
73
74void K_IStream::seekg( Imf::Int64 pos )
75{
76 m_dev->seek( pos );
77}
78
79void K_IStream::clear( )
80{
81 // TODO
82}
83
84/* this does a conversion from the ILM Half (equal to Nvidia Half)
85 * format into the normal 32 bit pixel format. Process is from the
86 * ILM code.
87 */
88QRgb RgbaToQrgba(struct Imf::Rgba imagePixel)
89{
90 float r,g,b,a;
91
92 // 1) Compensate for fogging by subtracting defog
93 // from the raw pixel values.
94 // Response: We work with defog of 0.0, so this is a no-op
95
96 // 2) Multiply the defogged pixel values by
97 // 2^(exposure + 2.47393).
98 // Response: We work with exposure of 0.0.
99 // (2^2.47393) is 5.55555
100 r = imagePixel.r * 5.55555;
101 g = imagePixel.g * 5.55555;
102 b = imagePixel.b * 5.55555;
103 a = imagePixel.a * 5.55555;
104
105 // 3) Values, which are now 1.0, are called "middle gray".
106 // If defog and exposure are both set to 0.0, then
107 // middle gray corresponds to a raw pixel value of 0.18.
108 // In step 6, middle gray values will be mapped to an
109 // intensity 3.5 f-stops below the display's maximum
110 // intensity.
111 // Response: no apparent content.
112
113 // 4) Apply a knee function. The knee function has two
114 // parameters, kneeLow and kneeHigh. Pixel values
115 // below 2^kneeLow are not changed by the knee
116 // function. Pixel values above kneeLow are lowered
117 // according to a logarithmic curve, such that the
118 // value 2^kneeHigh is mapped to 2^3.5 (in step 6,
119 // this value will be mapped to the display's
120 // maximum intensity).
121 // Response: kneeLow = 0.0 (2^0.0 => 1); kneeHigh = 5.0 (2^5 =>32)
122 if (r > 1.0)
123 r = 1.0 + Imath::Math<float>::log ((r-1.0) * 0.184874 + 1) / 0.184874;
124 if (g > 1.0)
125 g = 1.0 + Imath::Math<float>::log ((g-1.0) * 0.184874 + 1) / 0.184874;
126 if (b > 1.0)
127 b = 1.0 + Imath::Math<float>::log ((b-1.0) * 0.184874 + 1) / 0.184874;
128 if (a > 1.0)
129 a = 1.0 + Imath::Math<float>::log ((a-1.0) * 0.184874 + 1) / 0.184874;
130//
131// 5) Gamma-correct the pixel values, assuming that the
132// screen's gamma is 0.4545 (or 1/2.2).
133 r = Imath::Math<float>::pow (r, 0.4545);
134 g = Imath::Math<float>::pow (g, 0.4545);
135 b = Imath::Math<float>::pow (b, 0.4545);
136 a = Imath::Math<float>::pow (a, 0.4545);
137
138// 6) Scale the values such that pixels middle gray
139// pixels are mapped to 84.66 (or 3.5 f-stops below
140// the display's maximum intensity).
141//
142// 7) Clamp the values to [0, 255].
143 return qRgba( (unsigned char) (Imath::clamp ( r * 84.66f, 0.f, 255.f ) ),
144 (unsigned char) (Imath::clamp ( g * 84.66f, 0.f, 255.f ) ),
145 (unsigned char) (Imath::clamp ( b * 84.66f, 0.f, 255.f ) ),
146 (unsigned char) (Imath::clamp ( a * 84.66f, 0.f, 255.f ) ) );
147}
148
149EXRHandler::EXRHandler()
150{
151}
152
153bool EXRHandler::canRead() const
154{
155 if (canRead(device())) {
156 setFormat("exr");
157 return true;
158 }
159 return false;
160}
161
162QByteArray EXRHandler::name() const
163{
164 // TODO
165 return QByteArray("exr");
166}
167
168bool EXRHandler::read( QImage *outImage )
169{
170 try
171 {
172 int width, height;
173
174 K_IStream istr( device(), QByteArray() );
175 Imf::RgbaInputFile file( istr );
176 Imath::Box2i dw = file.dataWindow();
177
178 width = dw.max.x - dw.min.x + 1;
179 height = dw.max.y - dw.min.y + 1;
180
181 Imf::Array2D<Imf::Rgba> pixels;
182 pixels.resizeErase (height, width);
183
184 file.setFrameBuffer (&pixels[0][0] - dw.min.x - dw.min.y * width, 1, width);
185 file.readPixels (dw.min.y, dw.max.y);
186
187 QImage image(width, height, QImage::Format_RGB32);
188 if( image.isNull())
189 return false;
190
191 // somehow copy pixels into image
192 for ( int y=0; y < height; y++ ) {
193 for ( int x=0; x < width; x++ ) {
194 // copy pixels(x,y) into image(x,y)
195 image.setPixel( x, y, RgbaToQrgba( pixels[y][x] ) );
196 }
197 }
198
199 *outImage = image;
200
201 return true;
202 }
203 catch (const std::exception &exc)
204 {
205 kDebug() << exc.what();
206 return false;
207 }
208}
209
210
211bool EXRHandler::write( const QImage &image )
212{
213 // TODO: stub
214 Q_UNUSED( image );
215 return false;
216}
217
218
219bool EXRHandler::canRead(QIODevice *device)
220{
221 if (!device) {
222 qWarning("EXRHandler::canRead() called with no device");
223 return false;
224 }
225
226 const QByteArray head = device->peek(4);
227
228 return Imf::isImfMagic( head.data() );
229}
230
231
232/* --- Plugin --- */
233
234QStringList EXRPlugin::keys() const
235{
236 return QStringList() << "exr" << "EXR";
237}
238
239
240QImageIOPlugin::Capabilities EXRPlugin::capabilities(QIODevice *device, const QByteArray &format) const
241{
242 if ( format == "exr" || format == "EXR" )
243 return Capabilities(CanRead);
244 if ( !format.isEmpty() )
245 return 0;
246 if ( !device->isOpen() )
247 return 0;
248
249 Capabilities cap;
250 if (device->isReadable() && EXRHandler::canRead(device))
251 cap |= CanRead;
252 return cap;
253}
254
255QImageIOHandler *EXRPlugin::create(QIODevice *device, const QByteArray &format) const
256{
257 QImageIOHandler *handler = new EXRHandler;
258 handler->setDevice(device);
259 handler->setFormat(format);
260 return handler;
261}
262
263Q_EXPORT_STATIC_PLUGIN( EXRPlugin )
264Q_EXPORT_PLUGIN2( exr, EXRPlugin )
265