我已经开始使用 OpenEXR 加载 EXR 图像。我必须使用浮点类型来获取 RGB 像素。
对于 RGB 图像，加载没有问题，使用以下代码：
ImfInputFile *iFile = ImfOpenInputFile(filename);
FrameBuffer fb;
const Header &iHeader = iFile.header();
bool hasRed = false, hasGreen = false, hasBlue = false;
bool hasY = false;
Box2i dw = iHeader.dataWindow();
int width = dw.max.x-dw.min.x+1;
int height = dw.max.y-dw.min.y+1;
for (ChannelList::ConstIterator it = iHeader.channels().begin(), ite = iHeader.channels().end(); it != ite; it++) {
if ((strcmp(it.name(), "R") == 0)) { hasRed = true; }
if ((strcmp(it.name(), "G") == 0)) { hasGreen = true; }
if ((strcmp(it.name(), "B") == 0)) { hasBlue = true; }
if (it.channel().type != HALF) {
HDR_LOG("Unable to open EXR file \"%s\" (unsupported data type %s)", filename, it.channel().type);
return (IEFileCantOpen);
}
}
if ((hasRed == true) || (hasGreen == true) || (hasBlue == true)) {
fb.insert("R", Slice(
Imf::FLOAT, (char*)((char*)image->data + (sizeof(float) * 0)),
sizeof(float) * 3,
sizeof(float) * width * 3,
1, 1,
0.0
)
);
fb.insert("G", Slice(
Imf::FLOAT, (char*)((char*)image->data + (sizeof(float) * 1)),
sizeof(float) * 3,
sizeof(float) * width * 3,
1, 1,
0.0
)
);
fb.insert("B", Slice(
Imf::FLOAT, (char*)((char*)image->data + (sizeof(float) * 2)),
sizeof(float) * 3,
sizeof(float) * width * 3,
1, 1,
0.0
)
);
iFile.setFrameBuffer(fb);
if (ReadImage(filename, iFile, dw.min.y, dw.max.y) == IEFileReadError) {
HDR_LOG("There was a generic error on loading the EXR image \"%s\". Image could be corrupted.", filename);
return (IEFileReadError);
}
image->unproc = 1;
return (IENoError);
} else {
char sChannels[2048] = { '\0' };
for (ChannelList::ConstIterator it = iHeader.channels().begin(), ite = iHeader.channels().end(); it != ite; it++) {
strcat(sChannels, it.name());
strcat(sChannels, " ");
}
HDR_LOG("Unable to open EXR file (unknown channels set: %s)", sChannels);
return (IEFileReadError);
}
}
但我想知道这个库如何解码/转换 Y-RY-GY 图像（亮度 + 色度通道）并获得浮点 RGB 像素数据。