ImageMagick:处理TIFF时如何摆脱有关 "Unknown field"的TIFFWarnings/768消息？

Question

我将ETOPO1.tif处理到一个裁剪好的山坡阴影中。

我得到a tiff image看起来像:

当我通过ImageMagick处理它时，它成功运行。但是我收到以下警告消息集:

convert Yug-shadedrelief.tmp.tif -fuzz 7% -fill "#FFFFFF" -opaque "#DDDDDD"  whited.jpg     # lighter (0.9M)

 convert.im6: Unknown field with tag 33550 (0x830e) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/768.
 convert.im6: Unknown field with tag 33922 (0x8482) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/768.
 convert.im6: Unknown field with tag 34735 (0x87af) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/768.
 convert.im6: Unknown field with tag 34736 (0x87b0) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/768.
 convert.im6: Unknown field with tag 34737 (0x87b1) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/768.
 convert.im6: Unknown field with tag 42113 (0xa481) encountered. `TIFFReadDirectory' @ warning/tiff.c/TIFFWarnings/768.

我的.tif是否已损坏？

我应该怎么做才能删除此消息？

Answer 1

与您原来的标题(我已更改)不同，这不是“错误”消息，而只是警告:

TIFFReadDirectory: Warning, Unknown field with tag 33550 (0x830e) encountered. [...]
TIFFReadDirectory: Warning, Unknown field with tag 33922 (0x8482) encountered. [...]
TIFFReadDirectory: Warning, Unknown field with tag 34735 (0x87af) encountered. [...]
[...]

此处列出的标签是GeoTIFF的 private tags 。看这里:

http://www.awaresystems.be/imaging/tiff/tifftags/private.html

要查看它们的内容(可能对您没有什么意义)，可以使用 tiffdump(或 tiffutil -dump)实用程序。 exiftool有可能向您显示这些标签的含义:

 exiftool -a -U -u -g1 Yug-Shadedrelief.tmp.tif

-u和 -U也应该提取所有未知(到 exiftool)标签。如果您的输出中没有“垃圾”，那么 exiftool可以根据所看到的内容来回显示标题，所以:-)

也许您可以选择删除这些标签？ exiftool也可以为您做...

如果您只想让烦人的消息视而不见，而又不更改TIFF，则对命令执行stderr的 2> /dev/null重定向就足够了:

convert                    \
  Yug-shadedrelief.tmp.tif \
 -fuzz 7%                  \
 -fill "#FFFFFF"           \
 -opaque "#DDDDDD"         \
  whited.jpg               \
  2>/dev/null

更新

 Code |  Code |                     |
(dec) | (hex) | Tag Name            | Short Description
------+-------+---------------------+--------------------------------------------------------
33550 | 830E  | ModelPixelScaleTag  | Used in interchangeable GeoTIFF files
33922 | 8482  | ModelTiepointTag    | Originally part of Intergraph's GeoTIFF, 
34735 | 87af  | GeoKeyDirectoryTag  | Used in interchangeable GeoTIFF files
34736 | 87b0  | GeoDoubleParamsTag  | Used in interchangeable GeoTIFF files
34737 | 87b1  | GeoAsciiParamsTag   | Used in interchangeable GeoTIFF files
42113 | a481  | GDAL_NODATA         | Used by GDAL lib, contains ASCII encoded nodata or ...

说明:

33550:“...可选，用于定义栅格和模型空间之间的精确仿射变换...。”

33922:“...也称为'GeoreferenceTag'。此标签存储栅格->模型联络点对...”

34735:“...也称为'ProjectionInfoTag'和'CoordSystemInfoTag'”

34736:“...用于存储所有由GeoKeyDirectoryTag引用的DOUBLE值的所有GeoKey ...”

34737:“...用于存储所有由ASCII键值的GeoKey，由GeoKeyDirectoryTag引用”

42113:“...用于标记没有可用信息的地理空间区域的特殊像素值...”