These fields need to be set before you can start handing imagedata to libtiff.
在开始将图像数据交给libtiff之前，需要设置这些字段。
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The ASTER team released this image in June 2009 to promote its new global digital elevation model, which remains the most complete and consistent dataset of its kind.
The imagedata of the photo set was compressed with IBR compression algorithms such as the block coder, the reference coder and multidimensional wavelet transform.