Python+gdal裁剪遥感图像出现“Warning 1: TIFFReadDirectory:Sum of Photometric type-related color channels ……”

Posted 2022-06-29 空中旋转篮球

1.错误描述

运行环境：windows10、pycharm、python3.7、gdal等

python使用GDAL 裁剪遥感图像的时候出现以下警告：

“Warning 1: TIFFReadDirectory:Sum of Photometric type-related color channels and ExtraSamples doesn't match SamplesPerPixel. Defining non-color channels as ExtraSamples.”

使用的代码段：

out_ds = gdal.Warp(output_image,#output file full path
                   ds,#input file 2 ds
                   format='GTiff',
                   outputBounds=(x_left, x_bottom, x_right, x_top),
                   dstNodata=0)

Warp函数有很多参数选项：https://gdal.org/python/https://gdal.org/python/

Warp(destNameOrDestDS, srcDSOrSrcDSTab, **kwargs) 
Warp one or several datasets.
Arguments are :
  destNameOrDestDS --- Output dataset name or object
  srcDSOrSrcDSTab --- an array of Dataset objects or filenames, or a Dataset object or a filename
Keyword arguments are :
  options --- return of gdal.WarpOptions(), string or array of strings
  other keywords arguments of gdal.WarpOptions()
If options is provided as a gdal.WarpOptions() object, other keywords are ignored.

WarpOptions(options=None, format=None, outputBounds=None, 
outputBoundsSRS=None, xRes=None, yRes=None, targetAlignedPixels=False, 
width=0, height=0, srcSRS=None, dstSRS=None, coordinateOperation=None, 
srcAlpha=False, dstAlpha=False, warpOptions=None, errorThreshold=None, 
warpMemoryLimit=None, creationOptions=None, outputType=gdalconst.GDT_Unknown, 
workingType=gdalconst.GDT_Unknown, resampleAlg=None, srcNodata=None, dstNodata=None, 
multithread=False, tps=False, rpc=False, geoloc=False, polynomialOrder=None, 
transformerOptions=None, cutlineDSName=None, cutlineLayer=None, cutlineWhere=None, 
cutlineSQL=None, cutlineBlend=None, cropToCutline=False, copyMetadata=True, 
metadataConflictValue=None, setColorInterpretation=False, overviewLevel='AUTO', 
callback=None, callback_data=None)

参数描述：

Create a WarpOptions() object that can be passed to gdal.Warp()
Keyword arguments are :
  options --- can be be an array of strings, a string or let empty and filled from other keywords.
  format --- output format ("GTiff", etc...)
  outputBounds --- output bounds as (minX, minY, maxX, maxY) in target SRS
  outputBoundsSRS --- SRS in which output bounds are expressed, in the case they are not expressed in dstSRS
  xRes, yRes --- output resolution in target SRS
  targetAlignedPixels --- whether to force output bounds to be multiple of output resolution
  width --- width of the output raster in pixel
  height --- height of the output raster in pixel
  srcSRS --- source SRS
  dstSRS --- output SRS
  coordinateOperation -- coordinate operation as a PROJ string or WKT string
  srcAlpha --- whether to force the last band of the input dataset to be considered as an alpha band
  dstAlpha --- whether to force the creation of an output alpha band
  outputType --- output type (gdalconst.GDT_Byte, etc...)
  workingType --- working type (gdalconst.GDT_Byte, etc...)
  warpOptions --- list of warping options
  errorThreshold --- error threshold for approximation transformer (in pixels)
  warpMemoryLimit --- size of working buffer in MB
  resampleAlg --- resampling mode
  creationOptions --- list of creation options
  srcNodata --- source nodata value(s)
  dstNodata --- output nodata value(s)
  multithread --- whether to multithread computation and I/O operations
  tps --- whether to use Thin Plate Spline GCP transformer
  rpc --- whether to use RPC transformer
  geoloc --- whether to use GeoLocation array transformer
  polynomialOrder --- order of polynomial GCP interpolation
  transformerOptions --- list of transformer options
  cutlineDSName --- cutline dataset name
  cutlineLayer --- cutline layer name
  cutlineWhere --- cutline WHERE clause
  cutlineSQL --- cutline SQL statement
  cutlineBlend --- cutline blend distance in pixels
  cropToCutline --- whether to use cutline extent for output bounds
  copyMetadata --- whether to copy source metadata
  metadataConflictValue --- metadata data conflict value
  setColorInterpretation --- whether to force color interpretation of input bands to output bands
  overviewLevel --- To specify which overview level of source files must be used
  callback --- callback method
  callback_data --- user data for callback

这个错误是在裁剪图像之前出现的，不过也计算出来的结果，打开计算结果查看也没有太大问题。

使用的数据有19个波段，一连出现了17行这个警告。

2.问题分析

2.1 google搜索

因为从4个CMYK通道转移到3个RGB通道，这就是为什么我们的图像颜色变了。

正如谷歌上所看到的:“RGB指的是光的三原色，红、绿和蓝，用于显示器、电视屏幕、数码相机和扫描仪。CMYK指的是颜料的原色:青色、品红、黄色、黑色. ...当从RGB转换到CMYK时，我们呢可能会注意到颜色的变化。”

警告意味着图像每个像素有4个样本，但Protometric TIFF标签设置为RGB，没有ExtraSamples标签设置。GDAL给出了一个警告，因为3 + 0不等于4。然后它设置一个带为ExtraSample，现在3 + 1等于4，一切都是OK的，至少在技术上。

2.2 使用 GDAL Python 读取大栅格获取警告 | 智问智答

意味着创建 TIFF 文件的作者将元数据写入错误。也许元数据告诉图像是没有额外样本（波段）的 RGB 类型，但实际上图像有四个波段，GDAL 将其视为 RGBA。通过这样做，GDAL 至少不会丢弃一个波段，但它可能会对额外波段的作用做出错误的猜测，这不一定是 alpha 但也可能包含数据（例如 RGB+Near Infrared）.

3.解决办法

我加一行代码：

options=["TILED=YES", "COMPRESS=LZW"],#影像压缩方式选择

没有报这个错误了，不过图像打开查看的时候还是没有压缩，没起作用。

……

其他办法我也在探索中，可能设置某个参数选项可以解决，欢迎大佬们留言交流！