Skip to content

HDR: speed up reading by around 4x #3590

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 7, 2022
Merged

HDR: speed up reading by around 4x #3590

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
76 changes: 72 additions & 4 deletions src/hdr.imageio/hdrinput.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ OIIO_PLUGIN_NAMESPACE_BEGIN
// .hdr / .rgbe files - HDR files from Radiance
//
// General info on the hdr/rgbe format can be found at:
// http://local.wasp.uwa.edu.au/~pbourke/dataformats/pic/
// http://paulbourke.net/dataformats/pic/
//
// Also see Greg Ward's "Real Pixels" chapter in Graphics Gems II for an
// explanation of the encoding that's used in Radiance rgba files.
Expand Down Expand Up @@ -115,15 +115,83 @@ OIIO_EXPORT const char* hdr_input_extensions[] = { "hdr", "rgbe", nullptr };
OIIO_PLUGIN_EXPORTS_END


// Table of ldexpf(1.0f, i - (int)(128 + 8)) values.
// Note: Ward uses ldexp(col+0.5,exp-(128+8)). However we wanted pixels
// in the range [0,1] to map back into the range [0,1].
static const float exponent_table[256] = {
1.1479437e-41f, 2.2958874e-41f, 4.5917748e-41f, 9.1835496e-41f,
1.8367099e-40f, 3.6734198e-40f, 7.3468397e-40f, 1.4693679e-39f,
2.9387359e-39f, 5.8774718e-39f, 1.1754944e-38f, 2.3509887e-38f,
4.7019774e-38f, 9.4039548e-38f, 1.880791e-37f, 3.7615819e-37f,
7.5231638e-37f, 1.5046328e-36f, 3.0092655e-36f, 6.0185311e-36f,
1.2037062e-35f, 2.4074124e-35f, 4.8148249e-35f, 9.6296497e-35f,
1.9259299e-34f, 3.8518599e-34f, 7.7037198e-34f, 1.540744e-33f,
3.0814879e-33f, 6.1629758e-33f, 1.2325952e-32f, 2.4651903e-32f,
4.9303807e-32f, 9.8607613e-32f, 1.9721523e-31f, 3.9443045e-31f,
7.8886091e-31f, 1.5777218e-30f, 3.1554436e-30f, 6.3108872e-30f,
1.2621774e-29f, 2.5243549e-29f, 5.0487098e-29f, 1.009742e-28f,
2.0194839e-28f, 4.0389678e-28f, 8.0779357e-28f, 1.6155871e-27f,
3.2311743e-27f, 6.4623485e-27f, 1.2924697e-26f, 2.5849394e-26f,
5.1698788e-26f, 1.0339758e-25f, 2.0679515e-25f, 4.1359031e-25f,
8.2718061e-25f, 1.6543612e-24f, 3.3087225e-24f, 6.6174449e-24f,
1.323489e-23f, 2.646978e-23f, 5.2939559e-23f, 1.0587912e-22f,
2.1175824e-22f, 4.2351647e-22f, 8.4703295e-22f, 1.6940659e-21f,
3.3881318e-21f, 6.7762636e-21f, 1.3552527e-20f, 2.7105054e-20f,
5.4210109e-20f, 1.0842022e-19f, 2.1684043e-19f, 4.3368087e-19f,
8.6736174e-19f, 1.7347235e-18f, 3.469447e-18f, 6.9388939e-18f,
1.3877788e-17f, 2.7755576e-17f, 5.5511151e-17f, 1.110223e-16f,
2.220446e-16f, 4.4408921e-16f, 8.8817842e-16f, 1.7763568e-15f,
3.5527137e-15f, 7.1054274e-15f, 1.4210855e-14f, 2.8421709e-14f,
5.6843419e-14f, 1.1368684e-13f, 2.2737368e-13f, 4.5474735e-13f,
9.094947e-13f, 1.8189894e-12f, 3.6379788e-12f, 7.2759576e-12f,
1.4551915e-11f, 2.910383e-11f, 5.8207661e-11f, 1.1641532e-10f,
2.3283064e-10f, 4.6566129e-10f, 9.3132257e-10f, 1.8626451e-09f,
3.7252903e-09f, 7.4505806e-09f, 1.4901161e-08f, 2.9802322e-08f,
5.9604645e-08f, 1.1920929e-07f, 2.3841858e-07f, 4.7683716e-07f,
9.5367432e-07f, 1.9073486e-06f, 3.8146973e-06f, 7.6293945e-06f,
1.5258789e-05f, 3.0517578e-05f, 6.1035156e-05f, 0.00012207031f,
0.00024414062f, 0.00048828125f, 0.0009765625f, 0.001953125f,
0.00390625f, 0.0078125f, 0.015625f, 0.03125f,
0.0625f, 0.125f, 0.25f, 0.5f,
1.0f, 2.0f, 4.0f, 8.0f,
16.0f, 32.0f, 64.0f, 128.0f,
256.0f, 512.0f, 1024.0f, 2048.0f,
4096.0f, 8192.0f, 16384.0f, 32768.0f,
65536.0f, 131072.0f, 262144.0f, 524288.0f,
1048576.0f, 2097152.0f, 4194304.0f, 8388608.0f,
16777216.0f, 33554432.0f, 67108864.0f, 1.3421773e+08f,
2.6843546e+08f, 5.3687091e+08f, 1.0737418e+09f, 2.1474836e+09f,
4.2949673e+09f, 8.5899346e+09f, 1.7179869e+10f, 3.4359738e+10f,
6.8719477e+10f, 1.3743895e+11f, 2.7487791e+11f, 5.4975581e+11f,
1.0995116e+12f, 2.1990233e+12f, 4.3980465e+12f, 8.796093e+12f,
1.7592186e+13f, 3.5184372e+13f, 7.0368744e+13f, 1.4073749e+14f,
2.8147498e+14f, 5.6294995e+14f, 1.1258999e+15f, 2.2517998e+15f,
4.5035996e+15f, 9.0071993e+15f, 1.8014399e+16f, 3.6028797e+16f,
7.2057594e+16f, 1.4411519e+17f, 2.8823038e+17f, 5.7646075e+17f,
1.1529215e+18f, 2.305843e+18f, 4.611686e+18f, 9.223372e+18f,
1.8446744e+19f, 3.6893488e+19f, 7.3786976e+19f, 1.4757395e+20f,
2.9514791e+20f, 5.9029581e+20f, 1.1805916e+21f, 2.3611832e+21f,
4.7223665e+21f, 9.444733e+21f, 1.8889466e+22f, 3.7778932e+22f,
7.5557864e+22f, 1.5111573e+23f, 3.0223145e+23f, 6.0446291e+23f,
1.2089258e+24f, 2.4178516e+24f, 4.8357033e+24f, 9.6714066e+24f,
1.9342813e+25f, 3.8685626e+25f, 7.7371252e+25f, 1.547425e+26f,
3.0948501e+26f, 6.1897002e+26f, 1.23794e+27f, 2.4758801e+27f,
4.9517602e+27f, 9.9035203e+27f, 1.9807041e+28f, 3.9614081e+28f,
7.9228163e+28f, 1.5845633e+29f, 3.1691265e+29f, 6.338253e+29f,
1.2676506e+30f, 2.5353012e+30f, 5.0706024e+30f, 1.0141205e+31f,
2.028241e+31f, 4.0564819e+31f, 8.1129638e+31f, 1.6225928e+32f,
3.2451855e+32f, 6.4903711e+32f, 1.2980742e+33f, 2.5961484e+33f,
5.1922969e+33f, 1.0384594e+34f, 2.0769187e+34f, 4.1538375e+34f,
8.307675e+34f, 1.661535e+35f, 3.32307e+35f, 6.64614e+35f,
};


/* standard conversion from rgbe to float pixels */
/* note: Ward uses ldexp(col+0.5,exp-(128+8)). However we wanted pixels */
/* in the range [0,1] to map back into the range [0,1]. */
inline void
rgbe2float(float& red, float& green, float& blue, unsigned char rgbe[4])
{
if (rgbe[3]) { /*nonzero pixel*/
float f = ldexpf(1.0f, rgbe[3] - (int)(128 + 8));
float f = exponent_table[rgbe[3]];
red = rgbe[0] * f;
green = rgbe[1] * f;
blue = rgbe[2] * f;
Expand Down