KImgIO

exr.cpp

00001 // -*- C++;indent-tabs-mode: t; tab-width: 4; c-basic-offset: 4; -*-
00002 
00013 #include "config.h"
00014 
00015 #ifdef HAVE_EXR
00016 
00017 #include <ImfRgbaFile.h>
00018 #include <ImfStandardAttributes.h>
00019 #include <ImathBox.h>
00020 #include <ImfInputFile.h>
00021 #include <ImfBoxAttribute.h>
00022 #include <ImfChannelListAttribute.h>
00023 #include <ImfCompressionAttribute.h>
00024 #include <ImfFloatAttribute.h>
00025 #include <ImfIntAttribute.h>
00026 #include <ImfLineOrderAttribute.h>
00027 #include <ImfStringAttribute.h>
00028 #include <ImfVecAttribute.h>
00029 #include <ImfArray.h>
00030 #include <ImfConvert.h>
00031 
00032 #include <iostream>
00033 
00034 #include <stdlib.h>
00035 
00036 #include <kurl.h>
00037 #include <kprocess.h>
00038 #include <klocale.h>
00039 #include <kgenericfactory.h>
00040 #include <kdebug.h>
00041 
00042 #include <qimage.h>
00043 #include <qcstring.h>
00044 #include <qfile.h>
00045 #include <qdatetime.h>
00046 #include <qdict.h>
00047 #include <qvalidator.h>
00048 #include <qcolor.h>
00049 
00050 #include "exr.h"
00051 
00052 using namespace Imf;
00053 
00054 /* this does a conversion from the ILM Half (equal to Nvidia Half)
00055  * format into the normal 32 bit pixel format. Process is from the
00056  * ILM code.
00057  */
00058 QRgb RgbaToQrgba(struct Rgba imagePixel)
00059 {
00060     float r,g,b,a;
00061     
00062     //  1) Compensate for fogging by subtracting defog
00063     //     from the raw pixel values.
00064     // Response: We work with defog of 0.0, so this is a no-op        
00065 
00066     //  2) Multiply the defogged pixel values by
00067     //     2^(exposure + 2.47393).
00068     // Response: We work with exposure of 0.0.
00069     // (2^2.47393) is 5.55555 
00070     r = imagePixel.r * 5.55555;
00071     g = imagePixel.g * 5.55555;
00072     b = imagePixel.b * 5.55555;
00073     a = imagePixel.a * 5.55555;
00074 
00075     //  3) Values, which are now 1.0, are called "middle gray".
00076     //     If defog and exposure are both set to 0.0, then
00077     //     middle gray corresponds to a raw pixel value of 0.18.
00078     //     In step 6, middle gray values will be mapped to an
00079     //     intensity 3.5 f-stops below the display's maximum
00080     //     intensity.
00081     // Response: no apparent content.
00082 
00083     //  4) Apply a knee function.  The knee function has two
00084     //     parameters, kneeLow and kneeHigh.  Pixel values
00085     //     below 2^kneeLow are not changed by the knee
00086     //     function.  Pixel values above kneeLow are lowered
00087     //     according to a logarithmic curve, such that the
00088     //     value 2^kneeHigh is mapped to 2^3.5 (in step 6,
00089     //     this value will be mapped to the the display's
00090     //     maximum intensity).
00091     // Response: kneeLow = 0.0 (2^0.0 => 1); kneeHigh = 5.0 (2^5 =>32)
00092     if (r > 1.0)
00093         r = 1.0 + Imath::Math<float>::log ((r-1.0) * 0.184874 + 1) / 0.184874;
00094     if (g > 1.0)
00095         g = 1.0 + Imath::Math<float>::log ((g-1.0) * 0.184874 + 1) / 0.184874;
00096     if (b > 1.0)
00097         b = 1.0 + Imath::Math<float>::log ((b-1.0) * 0.184874 + 1) / 0.184874;
00098     if (a > 1.0)
00099         a = 1.0 + Imath::Math<float>::log ((a-1.0) * 0.184874 + 1) / 0.184874;
00100 //
00101 //  5) Gamma-correct the pixel values, assuming that the
00102 //     screen's gamma is 0.4545 (or 1/2.2).
00103     r = Imath::Math<float>::pow (r, 0.4545);
00104     g = Imath::Math<float>::pow (g, 0.4545);
00105     b = Imath::Math<float>::pow (b, 0.4545);
00106     a = Imath::Math<float>::pow (a, 0.4545);
00107 
00108 //  6) Scale the values such that pixels middle gray
00109 //     pixels are mapped to 84.66 (or 3.5 f-stops below
00110 //     the display's maximum intensity).
00111 //
00112 //  7) Clamp the values to [0, 255].
00113     return qRgba( char (Imath::clamp ( r * 84.66f, 0.f, 255.f ) ),
00114                   char (Imath::clamp ( g * 84.66f, 0.f, 255.f ) ),
00115                   char (Imath::clamp ( b * 84.66f, 0.f, 255.f ) ),
00116                   char (Imath::clamp ( a * 84.66f, 0.f, 255.f ) ) );
00117 }
00118 
00119 KDE_EXPORT void kimgio_exr_read( QImageIO *io )
00120 {
00121     try
00122     {
00123         int width, height;
00124 
00125         // This won't work if io is not QFile !
00126         RgbaInputFile file (QFile::encodeName(io->fileName()));
00127         Imath::Box2i dw = file.dataWindow();
00128 
00129         width  = dw.max.x - dw.min.x + 1;
00130         height = dw.max.y - dw.min.y + 1;
00131 
00132         Array2D<Rgba> pixels;
00133         pixels.resizeErase (height, width);
00134 
00135         file.setFrameBuffer (&pixels[0][0] - dw.min.x - dw.min.y * width, 1, width);
00136         file.readPixels (dw.min.y, dw.max.y);
00137 
00138         QImage image(width, height, 32, 0, QImage::BigEndian);
00139         if( image.isNull())
00140             return;
00141 
00142         // somehow copy pixels into image
00143         for ( int y=0; y < height; y++ ) {
00144             for ( int x=0; x < width; x++ ) {
00145                 // copy pixels(x,y) into image(x,y)
00146                 image.setPixel( x, y, RgbaToQrgba( pixels[y][x] ) );
00147             }
00148         }
00149 
00150         io->setImage( image );
00151         io->setStatus( 0 );
00152     }
00153     catch (const std::exception &exc)
00154     {
00155         kdDebug(399) << exc.what() << endl;
00156         return;
00157     }
00158 }
00159 
00160 
00161 KDE_EXPORT void kimgio_exr_write(QImageIO *)
00162 {
00163     // TODO: stub
00164 }
00165 
00166 
00167 #endif
KImgIO

exr.cpp

KImgIO

API Reference
