exr.cpp
// -*- C++;indent-tabs-mode: t; tab-width: 4; c-basic-offset: 4; -*-
#include "config.h"
#ifdef HAVE_EXR
#include <ImfRgbaFile.h>
#include <ImfStandardAttributes.h>
#include <ImathBox.h>
#include <ImfInputFile.h>
#include <ImfBoxAttribute.h>
#include <ImfChannelListAttribute.h>
#include <ImfCompressionAttribute.h>
#include <ImfFloatAttribute.h>
#include <ImfIntAttribute.h>
#include <ImfLineOrderAttribute.h>
#include <ImfStringAttribute.h>
#include <ImfVecAttribute.h>
#include <ImfArray.h>
#include <ImfConvert.h>
#include <iostream>
#include <stdlib.h>
#include <kurl.h>
#include <kprocess.h>
#include <klocale.h>
#include <kgenericfactory.h>
#include <kdebug.h>
#include <qimage.h>
#include <qcstring.h>
#include <qfile.h>
#include <qdatetime.h>
#include <qdict.h>
#include <qvalidator.h>
#include <qcolor.h>
#include "exr.h"
using namespace Imf;
/* this does a conversion from the ILM Half (equal to Nvidia Half)
* format into the normal 32 bit pixel format. Process is from the
* ILM code.
*/
QRgb RgbaToQrgba(struct Rgba imagePixel)
{
float r,g,b,a;
// 1) Compensate for fogging by subtracting defog
// from the raw pixel values.
// Response: We work with defog of 0.0, so this is a no-op
// 2) Multiply the defogged pixel values by
// 2^(exposure + 2.47393).
// Response: We work with exposure of 0.0.
// (2^2.47393) is 5.55555
r = imagePixel.r * 5.55555;
g = imagePixel.g * 5.55555;
b = imagePixel.b * 5.55555;
a = imagePixel.a * 5.55555;
// 3) Values, which are now 1.0, are called "middle gray".
// If defog and exposure are both set to 0.0, then
// middle gray corresponds to a raw pixel value of 0.18.
// In step 6, middle gray values will be mapped to an
// intensity 3.5 f-stops below the display's maximum
// intensity.
// Response: no apparent content.
// 4) Apply a knee function. The knee function has two
// parameters, kneeLow and kneeHigh. Pixel values
// below 2^kneeLow are not changed by the knee
// function. Pixel values above kneeLow are lowered
// according to a logarithmic curve, such that the
// value 2^kneeHigh is mapped to 2^3.5 (in step 6,
// this value will be mapped to the the display's
// maximum intensity).
// Response: kneeLow = 0.0 (2^0.0 => 1); kneeHigh = 5.0 (2^5 =>32)
if (r > 1.0)
r = 1.0 + Imath::Math<float>::log ((r-1.0) * 0.184874 + 1) / 0.184874;
if (g > 1.0)
g = 1.0 + Imath::Math<float>::log ((g-1.0) * 0.184874 + 1) / 0.184874;
if (b > 1.0)
b = 1.0 + Imath::Math<float>::log ((b-1.0) * 0.184874 + 1) / 0.184874;
if (a > 1.0)
a = 1.0 + Imath::Math<float>::log ((a-1.0) * 0.184874 + 1) / 0.184874;
//
// 5) Gamma-correct the pixel values, assuming that the
// screen's gamma is 0.4545 (or 1/2.2).
r = Imath::Math<float>::pow (r, 0.4545);
g = Imath::Math<float>::pow (g, 0.4545);
b = Imath::Math<float>::pow (b, 0.4545);
a = Imath::Math<float>::pow (a, 0.4545);
// 6) Scale the values such that pixels middle gray
// pixels are mapped to 84.66 (or 3.5 f-stops below
// the display's maximum intensity).
//
// 7) Clamp the values to [0, 255].
return qRgba( char (Imath::clamp ( r * 84.66f, 0.f, 255.f ) ),
char (Imath::clamp ( g * 84.66f, 0.f, 255.f ) ),
char (Imath::clamp ( b * 84.66f, 0.f, 255.f ) ),
char (Imath::clamp ( a * 84.66f, 0.f, 255.f ) ) );
}
KDE_EXPORT void kimgio_exr_read( QImageIO *io )
{
try
{
int width, height;
// This won't work if io is not QFile !
RgbaInputFile file (QFile::encodeName(io->fileName()));
Imath::Box2i dw = file.dataWindow();
width = dw.max.x - dw.min.x + 1;
height = dw.max.y - dw.min.y + 1;
Array2D<Rgba> pixels;
pixels.resizeErase (height, width);
file.setFrameBuffer (&pixels[0][0] - dw.min.x - dw.min.y * width, 1, width);
file.readPixels (dw.min.y, dw.max.y);
QImage image(width, height, 32, 0, QImage::BigEndian);
if( image.isNull())
return;
// somehow copy pixels into image
for ( int y=0; y < height; y++ ) {
for ( int x=0; x < width; x++ ) {
// copy pixels(x,y) into image(x,y)
image.setPixel( x, y, RgbaToQrgba( pixels[y][x] ) );
}
}
io->setImage( image );
io->setStatus( 0 );
}
catch (const std::exception &exc)
{
kdDebug(399) << exc.what() << endl;
return;
}
}
KDE_EXPORT void kimgio_exr_write(QImageIO *)
{
// TODO: stub
}
#endif

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