OpenImageIO在调整大小时将hdr转换为png格式

Question

我正在尝试将.hdr和.exr图像转换为调整大小的.png图像。转换部分按预期工作，但当我尝试在保存之前调整图像大小时，结果只是一张黑色图像。我使用的是github最新的OpenImageIO。

// read in an HDR or exr image
 auto in = ImageInput::open (image_path.hdr);
 const ImageSpec& spec = in->spec();
 int w = spec.width;
 int h = spec.height;
 int channels = spec.nchannels;

 // convert float to UNIT8
 std::vector<unsigned char> pixels (w * h * channels);
 in->read_image (TypeDesc::UINT8, pixels.data());
 
 // resize and save to png format
 ImageSpec s;
 s.format = TypeDesc::UINT8;
 s.width = w;
 s.height = h;
 s.nchannels = channels;
 ImageBuf A (s, pixels.data());

// without resizing saving to .png works correctly
A.write(image_path.png);

// this results in an all black image
ROI roi (0, w/2, 0, h/2, 0, 1, 0,channels);
ImageBuf B; 
ImageBufAlgo::resize (B, A, "", 0, roi);
B.write(image_path.png);

Answer 1

原来在调整大小时，ImageSpec字段full_width和full_height也需要填写。当它们存在时，调整大小的工作与预期的一样。

ImageSpec s;
s.format = TypeDesc::UINT8;
s.width = w;
s.height = h;
s.full_width = w;
s.full_height = h;